# Appendix B-4

2011 Oil and Gas Inventory Enhancement Project for

CenSARA States

## 2011 Oil and Gas Emission Inventory Enhancement Project for CenSARA States

Prepared for:

CENTRAL STATES AIR RESOURCES

AGENCIES (CenSARA)

P.O. Box 617 Oklahoma City, OK 73101

Prepared by: ENVIRON International Corporation
773 San Marin Drive, Suite 2115 Novato, California, 94945
www.environcorp.com

P-415-899-0700

F-415-899-0707

Eastern Research Group, Inc. 1600 Perimeter Park Drive, Suite 200

Morrisville, NC 27560

www.erg.com
P-919 468-7800

F-919-468-7801

December 21, 2012December 2012



### Disclaimer: The data, type and level of controls, a nd emission limits in this final report and accompanying tool should be considered preliminary and under review by the states. In addition, emission and control factors applied in t his work may not reflect lower emission limits specified in state regulations for ozone non-attain ment areas and certain attainment areas influencing non-attainment areas. For final 2011 NE I data or for information relating to modified emission and control factors, please conta ct the individual state.December 2012



### i



## CONTENTS

1.0 EXECUTIVE SUMMARY .................................

................................................... ............... 1

2.0 INTRODUCTION ......................................

................................................... .................... 6

2.1 CENRAP Oil and Gas Emission Inventory .............

................................................... ......... 7

2.2 Literature Sources ................................

................................................... ........................ 8

3.0 OBJECTIVES ........................................

................................................... ....................... 11

4.0 EMISSIONS INVENTORY DESCRIPTION ...................

................................................... .... 13

4.1 Temporal and Geographic Scope .....................

................................................... .......... 13

4.2 Pollutants considered .............................

................................................... .................... 14

4.3 Scope of Emission Sources .........................

................................................... ................ 15

4.4 Oil and Gas Activity Updates for the CenSARA Region

................................................. 17

4.4.1 Obtaining Oil and Gas Activity Data ...............

................................................... .. 17

4.4.2 CenSARA Oil and Gas Production Statistics for 2011 ......................................... 22

5.0 INPUT DATA GATHERING ..............................

................................................... ............ 29

5.1 Industrial Surveys ................................

................................................... ....................... 29

5.1.1 Geographical Scope ................................

................................................... ......... 29

5.1.2 Survey Description and Development ................ ................................................ 30

5.1.3 Survey Outreach Process and Results ...............

.................................................. 31

5.2 State Permit Data Review ..........................

................................................... ................. 34

5.2.1 Minor Source Permits ..............................

................................................... ........ 34

5.2.2 Permit Data Mining Procedure and Examples ......... ........................................... 34

5.3 Literature Sources and Gap-Filling for Non-Surveyed Basins ....................................... 36

5.3.1 Reviewed literature ...............................

................................................... .......... 36

5.3.2 Inputs for emissions estimates of non-surveyed basi ns ..................................... 38

6.0 EMISSIONS CALCULATOR TOOL DEVELOPMENT ............. ............................................... 41

6.1 Structure of Emissions Tool .......................

................................................... ................. 41

6.2 Summary of methodologies used to estimate emissions for each source
category ..........................................

................................................... ............................ 44

6.2.1 Artificial Lifts ..................................

................................................... .................. 44

6.2.2 Wellhead Compressor Engines .......................

................................................... . 46

6.2.3 Lateral/Gathering Compressor Engines .............. ................................................ 48December 2012



### ii

6.2.4 Condensate tanks...................................

................................................... .......... 50

6.2.5 Dehydrators .......................................

................................................... .............. 53

6.2.6 Drilling Rigs .....................................

................................................... .................. 57

6.2.7 Pneumatic Devices .................................

................................................... .......... 61

6.2.8 Well Completions ..................................

................................................... ........... 64

6.2.9 Blowdowns .........................................

................................................... .............. 68

6.2.10 Hydraulic Fracturing Pumps ........................

................................................... ..... 71

6.2.11 Fugitive Leaks ....................................

................................................... ............... 72

6.2.12 Heaters ...........................................

................................................... .................. 77

6.2.13 Loading Emissions .................................

................................................... ........... 79

6.2.14 Gas-Actuated Pumps ................................

................................................... ........ 81

6.2.15 Mud Degassing .....................................

................................................... ............ 85

6.2.16 Crude Oil Tanks ...................................

................................................... ............. 88

6.2.17 Produced water tanks ..............................

................................................... ........ 91

6.2.18 Casinghead gas venting ............................

................................................... ........ 94

6.3 Output Emissions Summary ..........................

................................................... ............. 97

6.4 Formatting tool for NEI submission ................

................................................... ............ 97

7.0 RESULTS............................................

................................................... ........................ 98

7.1 2011 Oil and Gas Area Source Emissions ............

................................................... ....... 98

7.2 Discussion ........................................

................................................... ......................... 117

7.2.1 Major oil and gas area sources ....................

................................................... .. 117

7.2.2 Data Gap Findings .................................

................................................... ......... 120

7.2.3 Future work opportunities .........................

................................................... .... 128

8.0 CONCLUSIONS .......................................

................................................... ................. 130

9.0 REFERENCES ........................................

................................................... ................... 131



## APPENDICES

Appendix A: CenSARA States County List

Appendix B: Field Names for Production Data from HP DI

Appendix C: Electronic Appendix: Industry survey fo rms (Excel Workbooks)

Appendix D: Electronic Appendix: CenSARA Emissions Calculator Tools (Excel

Workbooks)December 2012



### iii



## TABLES
Table E-1. Key production statistics for basins in the CenSARA domain (HPDI,

2012). ............................................

................................................... ........................ 2

Table E-2. 2011 Basin-wide Emissions for the CenSA RA 2011 Oil and Gas Area

Source Inventory. .................................

................................................... ................ 4

Table 4-1. Major area sources of NOx, VOCs and HA Ps in the upstream oil and gas

sector. ...........................................

................................................... ...................... 16

Table 4-2. County-level activity data parameters needed for emissions

estimation.........................................

................................................... .................. 18

Table 4-3. Production and drilling data sources b y state............................................ ........... 19

Table 4-4. HPDI data coverage by state. .........

................................................... .................... 20

Table 4-5. Basin-wide production statistics for t he CenSARA region. ................................ ... 23

Table 4-6. Summary of production, well counts and spud count by state and

basin for CenSARA. ................................

................................................... ............. 25

Table 4-7. Summary of drilling activity by basin.

................................................... ................ 28

Table 5-1. Participating companies in the survey outreach effort. .................................. ..... 32

Table 5-2. Summary of survey responses and owners hip of responses by basin. ................ 32

Table 5-3. Examples of specific data fields gap-f illed by state permit data......................... .. 35

Table 5-4. Specific calculation inputs derived fr om literature sources. ............................ .... 37

Table 5-5. Input data assumptions for non-surveye d basins outside of Texas

(except Marathon Thrust Belt). ....................

................................................... ...... 39

Table 5-6. Data sources used for calculation inpu ts for non-surveyed basins in

Texas .............................................

................................................... ...................... 40

Table 6-1. Oil and gas emission source categories

. ................................................. .............. 41

Table 6-2. National default emissions factors for mud degassing by mud base. .................. 86

Table 7-1. Basin-wide emissions by area source ca tegory for 2011 in the CenSARA

domain. ...........................................

................................................... .................... 99

Table 7-2. Emissions Inventory for 2011 oil and g as sources in CenSARA States. ............... 114

Table 7-3. Quality assessment of input data used to estimate emissions for each

area source category and basin in CenSARA. ........ .............................................. 122



## FIGURES
Figure E-1. Oil and gas basins in the CenSARA dom ain. .............................................. .............. 1

Figure E-2. Active well counts by well type for ea ch basin in CenSARA (HPDI,

2012). ............................................

................................................... ........................ 3December 2012



### iv

Figure 4-1. Oil and gas basins in the CenSARA reg ion. .............................................. .............. 14

Figure 7-1. NOx emissions by source category (in tons per year). ................................... ..... 117

Figure 7-2. VOCs emissions by source category (in tons per year). .................................. .... 118

Figure 7-3. Methane emissions by source category (in tons per year). ............................... . 120December 2012



### 1



## 1.0 EXECUTIVE SUMMARY

The Central States Air Resource Agencies (CenSARA) has identified the need to improve the activity data and methodologies used by its member states to develop oil and gas area source emissions. CenSARA states, including Texas, Louisia na, Oklahoma, Arkansas, Kansas, Missouri and Nebraska need to develop 2011 area source inven tories of criteria pollutants (CO, SO 2 

### , NOx, VOCs, PM), selected hazardous air pollutants ( HAPs), hydrogen sulfide and methane to be

included in their submission to the 2011 National E missions Inventory (NEI). ENVIRON and the Eastern Research Group (ERG) reviewed the available data sources and collected basin-level specific emissions information for calendar year 20 11 through industry surveys to operators within the CenSARA domain. A map of the oil and gas basins within the CenSARA domain is shown in Figure E-1. As part of this Project, an Em issions Calculator Tool was developed which

facilitates calculations of emission estimates for calendar year 2011 and enables each CenSARA state to generate oil and gas area source emissions estimates and to format these emissions in an EIS-ready format for future NEI submissions.

Figure E-1. Oil and gas basins in the CenSARA doma in.

The following specific tasks were pursued as part o f this goal:

x Oil and gas production activity levels throughout t he CenSARA region including, but not limited to, the number of active wells by well type , gas production and oil production, spudDecember 2012



### 2

counts 1 

### , feet drilled, and water production were updated f or 2011 using the HPDI “DI Desktop” database, a commercial database that proce sses state-level oil and gas commission data into a comprehensive database of pr oduction statistics.

x Basin-level data on equipment, activity and emissio ns factors were developed or collected for estimating 2011 emissions from a variety of res ources including 1) oil and gas operator surveys, 2) state minor source permit applications, and 3) literature review.

x An Emissions Calculator Tool that estimates 2011 oi l and gas area source emissions at the basin and county level was developed: estimates are compiled within a worksheet tool, documented in this report, which enables CenSARA me mbers to update activity and emissions data at the basin and/or county level for future use. The tool is based on the existing emissions calculator developed by ERG for Texas (ERG, 2010) but expanded to include inventory enhancements performed in the cur rent study.

x A database program was developed to automatically c onvert the emissions estimated by the Calculator Tool into an EIS-ready format to fac ilitate NEI submissions. Data stored in the EIS staging tables can be converted into valid XML files that are in compliance with the CERS using an EPA-supplied XML File Generator tool. This program and the emissions calculator provide the necessary set of tools for CenSARA memb ers to both generate the oil and gas

emissions and format them for NEI submission.

The CenSARA domain represents a substantial percent age of the onshore oil and gas production in the continental United States. In 201 0, seven CenSARA oil and gas producing states (Texas, Oklahoma, Louisiana, Arkansas, Kansa s, Nebraska and Missouri) had a combined oil production of approximately 611 million barrels and a combined gas production of 12.8 trillion cubic feet (EIA, 2012), representing 48 % of total gas production and 31% of total oil production in the country. Key production statistic s are shown in Table E-1. Production statistics

obtained from the HPDI database were used as scalin g surrogates for estimating oil and gas area source emissions at the county level.

Table E-1. Key production statistics for basins in the CenSARA domain (HPDI, 2012).

Basin 2011 Statistics

Crude Oil

Production (1000 bbl/yr) Condensate

Production (1000 bbl/yr) Natural Gas

Production (BCF/yr) Spud Count
Anadarko Basin 38,850 23,404 1,668 1,484

Arkoma Basin 1,210 106 1,567 952
Bend Arch-Fort Worth Basin 27,124 3,712 2,088 1,534 Cambridge Arch-Central Kansas Uplift 17,441 939 11 843 Cherokee Platform 9,222 782 104 876

Denver Basin 393 751 1 6
East Texas Basin 15,403 6,062 1,839 629
Forest City Basin 1,329 18 0 773

Illinois Basin 0 0 3 0

1 Spud refers to the process of beginning to drill a well. A spud count is the number of wells that com menced drilling over a particular period of time.December 2012



### 3 Basin 2011 Statistics

Crude Oil

Production (1000 bbl/yr) Condensate

Production (1000 bbl/yr) Natural Gas

Production (BCF/yr) Spud Count Louisiana-Mississippi Salt Basins 14,781 2,151 2,506 707

Marathon Thrust Belt 4 82 42 8 Nemaha Uplift 4,620 1,078 23 133 Ozark Uplift 0 0 0 0
Palo Duro Basin 3,562 82 19 19

Permian Basin 299,041 5,683 529 2,201

Salina Basin 273 8 0 22 Sedgwick Basin 3,063 1,523 37 257

Southern Oklahoma 9,377 1,931 78 19 Western Gulf 144,930 61,147 2,102 1,671 CenSARA Region Total 590,621 109,459 12,615 12,134



### The number of active wells by well type is another key indicator of the oil and gas activity in the CenSARA region. Active well counts from the HPDI da tabase for each basin within CenSARA are shown in Figure E-2.

Figure E-2. Active well counts by well type for eac h basin in CenSARA (HPDI, 2012). - 20,000 40,000 60,000 80,000 100,000 120,000 140,000 160,000 180,000

Oil Well Count Gas Well CountDecember 2012



### 4

With the use of the Emissions Calculator Tools deve loped for this project, 2011 oil and gas area source emissions inventories were prepared for each oil and gas producing State within the CenSARA region. These inventories are highly detail ed in their geographical specificity by including emissions at basin, state and county leve ls, in the array of pollutants included (16 total), and in the array of source categories analy zed. Source categories included in the
inventory are:

x Artificial Lift Engines

x Wellhead Compressor Engines

x Lateral Compressor Engines

x Drilling Rigs

x Condensate Tanks

x Hydraulic Fracturing Pumps

x Well Completion Venting

x Blowdown Venting

x Casing Gas Venting

x Dehydrators

x Pneumatic Devices

x Heaters

x Crude Oil Tanks

x Produced Water Tanks

x Gas-Actuated Pneumatic Pumps

x Fugitive Emissions

x Mud Degassing

x Hydrocarbon Liquids Loading

x Flaring

Table E-2 shows a summary of resulting basin-wide e missions for 2011 from the oil and gas area source inventories developed here. This table only includes emissions for key pollutants of relevancy for air quality issues in the CenSARA dom ain. Emissions by source category are too extensive to include here but may be found in other sections of the report.

Table E-2. 2011 Basin-wide Emissions for the CenSAR A 2011 Oil and Gas Area Source
Inventory.

Basin NOX (TPY) VOCs (TPY) CH4 (TPY)

Anadarko Basin 108,952 273,066 708,483
Arkoma Basin 15,615 16,274 294,226
Bend Arch-Fort Worth Basin 144,032 147,646 458,542 Cambridge Arch-Central Kansas Uplift 9,340 39,794 86,424 Cherokee Platform 36,316 73,951 240,037
Denver Basin 1,547 7,693 11,984

East Texas Basin 128,840 100,632 364,708December 2012



### 5 Basin NOX (TPY) VOCs (TPY) CH4 (TPY)
Forest City Basin 4,345 8,186 19,015

Illinois Basin 15 16 373 Louisiana-Mississippi Salt Basins 39,832 40,341 158, 601
Marathon Thrust Belt 3,863 4,525 13,173 Nemaha Uplift 9,081 22,702 43,783 Ozark Uplift 0 0 0

Palo Duro Basin 5,879 6,570 17,978

Permian Basin 166,429 386,201 626,542

Salina Basin 82 610 995 Sedgwick Basin 11,948 25,364 41,127
Southern Oklahoma 7,491 30,292 56,054

Western Gulf 142,582 433,119 566,775
Grand Total CenSARA 836,191 1,616,982 3,708,820



### Review of the oil and gas area source emissions by source category suggests that NOx emissions are largely dominated by wellhead compressor emissi ons, particularly in basins with a large number of active gas wells. Other significant sourc es of NOx include lateral compressors, drilling rigs, and well-site heaters. Pneumatic dev ices are the most significant source of VOC and

methane emissions in most basins within the CenSARA region. In basins where significant production of condensate and crude oil occurs (for example the Permian and Western Gulf Basins), VOC emissions are dominated by condensate tank and crude oil tank losses. Other key

sources of VOC and methane emission include well bl owdowns, well-site fugitives and wellhead compressor engines.December 2012



### 6



## 2.0 INTRODUCTION

The Central States Air Resource Agencies (CenSARA) is a regional organization that supports the discussion of air quality issues between its member s and other interested parties, and aids in identifying options for air pollution control throu gh air quality statutes and regulations. CenSARA oil and gas producing states, which include Texas, Oklahoma, Louisiana, Arkansas, Kansas, Nebraska and Missouri, have determined that significant area source emissions of criteria pollutants (NOx, CO, SO 2 

### , VOCs) and greenhouse gases (GHGs) may be associat ed with exploration and production activities in the upstre am oil and gas sector. Oil and gas production in the remaining two CenSARA states (Iowa and Minne sota) is negligible. Over the last decade, oil and gas exploration and production in the Unite d States has grown significantly, primarily in the Rocky Mountain states, southern Central states, the Gulf of Mexico, and most recently in

the Marcellus Shale in the Northeastern U.S. This i s partly related to an increased production of unconventional oil and gas resources such as shale gas, produced in formations such as the Fayetteville Shale in Arkansas, Barnett Shale in Te xas and Haynesville Shale in Louisiana. In 2010, seven CenSARA states (Texas, Oklahoma, Louisi ana, Arkansas, Kansas, Nebraska and Missouri) had a combined oil production of approxim ately 611 million barrels and a combined gas production of 12.8 trillion cubic feet (EIA, 20 12), representing 48 % of total gas production and 31% of total oil production in the United State s. Sources of emissions in the upstream oil and gas sector include equipment and processes used in drilling, completion and production activities that are primarily located at or near we ll sites in active oil and gas fields. These nonpoint emissions sources are generally not monitored under major source permitting programs and may or may not be subject to minor source permi ts, making it difficult for states to identify and quantify their emissions and evaluate their col lective air quality impacts. Hence, area source emissions from the upstream sector remain a source of concern for CenSARA.

CenSARA sponsored this study to enhance available d ata and methodologies used by its member states to develop oil and gas area source em issions by reviewing and synthesizing available data and collecting additional data via o il and gas industry surveys. CenSARA states need to develop a 2011 area source inventory for cr iteria pollutants (CO, SO 2 

### , NOx, VOCs, PM), selected hazardous air pollutants (HAPs 2 

### ), hydrogen sulfide and methane to be included with

other emissions inventories submitted to the 2011 N ational Emissions Inventory (NEI). To achieve this, CenSARA contracted ENVIRON and subcon tractor Eastern Research Group (ERG) to research the available data sources and collect upd ated and basin-wide specific emissions information for upstream oil and gas sources throug hout the CenSARA region. In addition, an Emissions Calculator Tool was developed as part of this project that facilitates calculation of calendar year 2011 emission estimates and will enab le each CenSARA state to more easily generate emissions estimates for future inventories and NEI submissions.

2 Targeted HAPS include key VOC species – toluene, x ylene, formaldehyde, benzene, ethylbenzene, and n-h exane.December 2012



### 7



## 2.1 CENRAP Oil and Gas Emission Inventory

This study builds off the work performed by ENVIRON in 2008 for the Central Regional Air Planning Association (CENRAP). The CENRAP study was an oil and gas emissions inventory enhancement project for the CENRAP region, includin g Louisiana, Texas, Oklahoma, Arkansas, Kansas and Nebraska (Bar-Ilan, et al., 2008). The m ain objective of the CENRAP study was to develop recommendations for input data and detailed methodologies to improve CENRAP’s oil and gas area source inventories for the base year 2 002 and to develop future year projections for calendar year 2018. The study included estimati on of nitrogen oxides (NOx), volatile organic compounds (VOC), particulate matter (PM 10 

### ), carbon monoxide (CO), sulfur dioxide (SO 2 

### ) and other pollutants from oil and gas operations. The C ENRAP study represented an initial and important step towards providing CENRAP states with a means of developing their own estimates of oil and gas area source emissions. Ho wever, the study had certain limitations such

as:

x Limited Survey Participation: a limited survey outr each was performed in the study which attempted to gather emissions and activity data for upstream source categories from nine (9) major oil and gas producers in the CENRAP regio n. Even though participating companies covered a wide geographic range of activities and o wnership of production in the CENRAP domain, participation was very limited; only four c ompanies returned surveys with

sufficient and useful data.

x Lack of an Emissions Inventory: The CENRAP study wa s an inventory-enhancement project aimed to provide technical guidance and a set of in puts for CENRAP members to independently estimate emissions for oil and gas ar ea sources within their jurisdiction. The scope of the work did not include development of em ission inventories for the base year or the future year.

x Scope of Emissions Sources: some oil and gas source categories, including produced water (evaporative ponds, water tanks), drilling mud dega ssing and hydraulic fracturing engines

have often not been included in area source invento ries, generally due to lack of

information to characterize their emissions. The c urrent study expands the list of sources that were analyzed in CENRAP by now including: hydr aulic fracturing pumps, casing gas venting, produced water tanks, gas-actuated pneumat ic pumps, fugitive emissions from compressor seals, mud degassing, and hydrocarbon li quids loading.

x Use of State-by-State Databases for Production Stat istics: the CENRAP study relied on each state’s oil and gas conservation commission (OGCC) or equivalent agency’s database to obtain drilling and production statistics used to s cale emissions on a basin-wide level. This required the combination of data from individual st ates’ OGCC databases which may not all have a similar organizational structure. Databases can vary greatly in terms of format, the level of detail of the information tracked by each OGCC, and ultimately the availability of key statistics such as oil production, gas producti on, active well counts, spud counts, and water production. These inconsistencies impacted th e CENRAP study in that it was not possible to consistently incorporate low-level stat istics such well counts by type, separate condensate production and crude oil production esti mates, and separate natural gas production and casing gas production in all cases.December 2012



### 8

x Use of State Permit Data: Minor source permit appli cations can be a resource of geographicspecific activity and emissions data for area sourc e emissions inventories. Several states have minor source permitting programs that require an air permit for oil and gas production facilities (well sites) to operate. These permit ap plications contain detailed emissions calculations that characterize many upstream oil an d gas area sources, and they can be a useful source of field-type data for regional emiss ions inventories. The CENRAP study did not research minor permit applications to gap-fill data that could not be retrieved by industry surveys and literature reviews. The curren t work takes advantage of this resource.



## 2.2 Literature Sources

Recent studies have become available that contain u seful information for estimating emissions from oil and gas area sources including information from recent years and/or regions of interest to the CenSARA oil and gas emissions inventory. Som e of the studies and reports reviewed here

are:

Recommendations for Improvements to the CENRAP Stat es’ Oil and Gas Emissions Inventories (Bar-Ilan, et al., 2008): As discussed earlier, the CENRAP work included rec ommendations for input data and detailed methodologies to improve oi l and gas area source inventories within the CENRAP region for year 2002. During the develop ment of emissions inventories in this work for selected source categories, the CENRAP study wa s found to be the most up-to-date and regionally-specific source of input data available in the literature for the CenSARA domain. This was especially true for some particular categories such as fugitives and heaters that were not included in the industry surveys.

Haynesville Shale 2011 Emissions Inventory Update ( ENVIRON, 2012): This study is an update for calendar year 2011 of a previous comprehensive inventory of ozone precursor emissions (VOC, NOx, and CO) from natural gas exploration and production activities in the Haynesville Shale formation, covering its extent in Louisiana a nd Texas. The updated Haynesville Shale inventory is currently in its draft form at the tim e of the preparation of this report. The original study (ENVIRON, 2009) developed emissions for a bas e year 2009 and future annual projections from 2010 to 2020. Source categories included in th e inventory range from exploration and production phase to downstream sources; emissions s ources reviewed included: drill rigs, hydraulic fracturing, completion venting, well blow downs, fugitives, pneumatic devices, heaters, dehydrators, flaring, wellhead compressors , compressor stations and gas processing plants. In the latest study (ENVIRON, 2012) detaile d activity and emissions data on equipment, processes, well configuration, emissions factors, a nd usage were updated with data obtained through industry surveys to reflect activity for Ha ynesville Shale wells in 2011. The current oil and gas inventory for CenSARA applies selected prel iminary data derived from surveys in the Haynesville Shale 2011 draft inventory available as of October 2012 and under the consent of the sponsors of that project (NETAC). It must be no ted that data from the 2011 Haynesville Shale Inventory Update used in this work is in its draft form and may be revised when the 2011 Haynesville Shale update is finalized.December 2012



### 9

The US EPA 2010 National Greenhouse Gas Inventory ( EPA, 2012): This annual inventory is a comprehensive analysis of all greenhouse gas emissi ons sources and sinks in the United States, including those in the upstream oil and gas sector. The latest edition available covers years 1990 to 2010. The study has an independent analysis of emissions from natural gas systems that characterizes multiple source categories locat ed at the well-site and in the downstream sector. Efforts were made to adjust emissions facto rs with available data by broad geographic producing regions of the United States (Midcontinen t, Rocky Mountains, Gulf Coast, etc.) by accounting for regional average gas compositions an d emissions deductions from state regulations or voluntary actions. A separate analys is is available for petroleum systems, which analyzes greenhouse gas emissions for the upstream oil sector as well as the transportation and refining of crude; these emissions are estimated at a national level, i.e. no regional specificity. Since the 2009 edition of the inventory (EPA, 2011) , analysis of natural gas systems have incorporated adjustments to the inventory to accoun t for hydraulic fracturing in source categories like well completions and well workovers . A limitation of this inventory is that it is focused on greenhouse gases and thus provides limit ed information on criteria pollutant emissions. However, activity data in these GHG nati onal inventories have proven useful to gapfill missing information for emissions estimates.

The Climate Registry Oil and Gas Production Protoco l (TRC, 2010) : This is an annex to The Climate Registry’s (TRC) General Reporting Protocol (GRP) that provides guidance on estimating and reporting greenhouse gas emissions for members of TRC. The protocol focuses on emissions sources in the oil and gas exploration an d production sector and provides high-level and low-level methodologies to estimate emissions, along with national default emissions factors and sample calculations. The protocol is li mited to estimating emissions for greenhouse gases and thus does not provide emissions factors f or criteria pollutants. However, methodologies often include a conversion method to extrapolate emissions from one hydrocarbon gas to another based on gas analyses, w hich can then be applied to estimate VOC

and HAP emissions.

Texas Statewide Emissions Inventory from Oil and Ga s Production (ERG, 2010): This is a comprehensive emissions inventory for base year 200 8 characterizing area sources from upstream onshore oil and gas production sites in Te xas. The emissions inventory analyzes criteria pollutant emissions of volatile organic co mpounds (VOC), nitrogen oxides (NOx), carbon monoxide (CO), particulate matter and hazardous air pollutants (HAPs). Among the sources included are dehydrators, oil and condensate tanks, oil and condensate loading, and combustion sources such as drilling rigs, artificia l lift engines and compressors. The study compiled county-level activity data from the Texas Railroad Commission, and specific emissions and emission factor data for many source categories from multiple state and regional data sources such as vendor data and point source emissi ons inventory reports. As part of the study, an emissions calculator was developed to enable the Texas Commission on Environmental Quality to update the emissions inventory for futur e years by providing updated county-level activity data. Inventory development in the current CenSARA work for most Texas basins, except Permian, builds off the comprehensive databa se of activity and emissions factors compiled in this study.December 2012



### 10

WRAP Phase III Inventories (WRAP, 2012) : These inventories were developed by the Western Regional Air Partnership, a regional planning organ ization for the Rocky Mountain states similar

to CenSARA in the Central states. The Phase III in ventories were the first-ever attempt to develop detailed, bottom-up, basin-level criteria p ollutant inventories for all oil and gas area and point emissions sources. The inventories analy zed a wide range of activities including conventional, tight sands and CBM gas production, a nd oil production. The Phase III inventories cover many of the same source categories that are e valuated in the CenSARA inventories. Methodologies for estimating area source inventorie s, and emission factors and input activity

factors were drawn from the WRAP Phase III inventor ies as a gap-filling method where other

information was not available.December 2012



### 11



## 3.0 OBJECTIVES

States must prepare and submit an inventory of crit eria and hazardous air pollutant emissions from all emissions sources within their jurisdictio n every three years for inclusion in the National Emissions Inventory (NEI) compiled by the U.S. Environmental Protection Agency. This includes emissions from area sources in oil and gas systems. States’ submissions for the 2011 NEI are due by the end of 2012. CenSARA is aware th at there are data gaps and deficiencies in currently available data to characterize oil and ga s area sources and has sponsored this study to make improvements in the resources available for th e preparation of emissions inventories by developing reasonable and regionally-representative inputs for emissions calculations and by establishing a detailed and reproducible methodolog y for CenSARA members to apply in future NEI submissions. The following tasks were pursued i n an effort to achieve this goal:

x Updated oil and gas production activity throughout the CenSARA region: estimating emissions at a basin-wide level requires key produc tion surrogates to be compiled for the CenSARA domain on a county-level basis, and for the se to be grouped by the geographical basin limits to obtain basin-level activity. These key activity factors include (but are not limited to) number of active wells by well type, ga s production and oil production by well type, spud count, feet (depth) drilled by wellbore type, and water production by well type. ENVIRON/ERG compiled county-level activity data for calendar year 2011 for oil and gas producing CenSARA states; the goal was to use a sin gle, consistent source of production statistics instead of collecting data from various state agency datasets which may present data in varying formats.

x Compiled basin-level data on equipment, activity an d emissions factors for estimating emissions: ENVIRON researched and gathered data fro m a variety of resources, starting with 1) oil and gas operator surveys, 2) state mino r source permit applications, and 3) literature review, to obtain detailed basin-specifi c data on operations, equipment and processes related to upstream oil and gas area sour ces. The data collected included equipment counts, emissions factors, activity facto rs for equipment (e.g. annual hours of operation, load factors, tier level, etc.), and gas compositions.

x Developed an Emissions Calculator Tool that estimat es 2011 oil and gas area source emissions at the basin and county level: 2011 emiss ions estimates were compiled within a fully documented worksheet tool that enables CenSAR A members to update activity and emissions data at the basin and/or county level for future use. The tool is based on the existing emissions calculator developed by ERG for Texas (ERG, 2010) but expanded to include inventory enhancements performed in the cur rent study and added components that allow the states to update data by including s pecific control measures and adjusting

emission factors. A tool for each CenSARA state was developed which includes a summary of annual emissions by county, by basin, by polluta nt and by source classification codes (SCCs). Production statistics at the county and bas in level are also summarized within the

tool.

x Developed a database program to convert the emissio ns estimated by the Calculator Tool into an EIS-ready format for NEI submissions: A dat abase program was developed to read the emissions summary in the Emissions Calculator T ool and convert emissions estimatesDecember 2012



### 12

into an EIS-ready format by loading the inventory d ata into the EPA-supplied Consolidated Emissions Reporting Schema (CERS) EIS staging table s. The data stored in the EIS staging

tables can be converted into valid XML files that a re in compliance with the CERS using an EPA-supplied XML File Generator tool. This program and the emissions calculator provide the necessary set of tools for CenSARA members to b oth generate the oil and gas emissions

and format them for NEI submission.December 2012



### 13



## 4.0 EMISSIONS INVENTORY DESCRIPTION

4.1 Temporal and Geographic Scope

The current inventory enhancement aims to character ize emissions from oil and gas activities for a base year 2011. The base year 2011 in this Pr oject also aligns with the year inventoried in the upcoming EPA’s National Emissions Inventory (NE I) for which the CenSARA states must submit 2011 emissions data for sources in their jur isdictions by December 31 st 

### , 2012. The NEI is prepared every three years by the US EPA based prim arily upon emission estimates and emission model inputs provided by Regional, State, Local and Tribal air agencies.

Oil and gas facilities’ operational and equipment i nformation were collected through survey outreach for companies’ activities in 2011. Drillin g and production statistics (well counts, oil and gas production, spud count, etc.) for the CenSARA r egion were compiled for 2011. Final

emissions were calculated on an annual basis as the majority of the oil and gas sources operate throughout the year. Preparation of inventories for future years will be facilitated by the ability of CenSARA States to update activity levels and emi ssions data contained in the 2011 version of the Emissions Calculator Tool developed in this Pro ject.

The geographic scope of this inventory includes all CenSARA member states in which oil and gas activities took place during 2011 (Texas, Oklahoma, Louisiana, Arkansas, Kansas, Nebraska and Missouri). Oil and gas production in the remaining two CenSARA states (Iowa and Minnesota) is negligible. A map of oil and gas basins in the CenS ARA region is provided in Figure 4-1. Basin geographical boundaries were largely based on USGS definitions but were modified slightly to align with county boundaries for ease of reporting county-level emissions in this inventory. Thus, counties that are geographically split betwee n multiple basins were assigned to the single basin representing the largest geographic portion o f the county to avoid the complexity of allocating activity factors and emissions at the su b-county level.December 2012



### 14

Figure 4-1. Oil and gas basins in the CenSARA regi on.

Although activities can vary within a basin (e.g. b oth oil and gas operations), the geologically influenced characteristics of a basin (e.g. depth, pressure, presence of water, oil quality, gas composition) directly affect activity parameters th at describe oil and gas operations within the basin boundaries. A basin therefore represents a s ufficiently detailed but tractable geographic unit for development of emissions factors and other input data for oil and gas area sources. Oil and gas area source emissions were therefore estima ted for each basin based on equipment, activity and emissions factors compiled for the bas in. Emissions were then allocated to each county within the basin based on the by-county spat ial allocation surrogate (well counts, production and drilling) applicable to each source category. Counties falling within each basin are listed in Table A-1 of Appendix A.



## 4.2 Pollutants considered

Pollutants included in the oil and gas area source inventory are:

Criteria pollutants: carbon monoxide (CO), sulfur d ioxide (SO 2 

### ), nitrogen oxides (NOx), volatile organic compounds (VOCs), and particulate matter (s pecifically, PM10 and primary/direct PM2.5).

Greenhouse Gases (GHGs): methane, carbon dioxide an d nitrous oxide.December 2012



### 15

Hazardous Air Pollutants (HAPs): Calculation of HAP s emissions was limited by the availability of emissions factors for indirect sources (such as com bustion sources) and the availability of detailed gas speciation profiles for direct sources (such as leaking and venting area sources). The list of HAPs included in this inventory was bas ed on those pollutants (benzene, ethylbenzene, toluene, xylene, formaldehyde and n-h exane) for which emissions data was available. It must be noted that gas analyses obtai ned through company surveys and literature data did not consistently include HAP concentration s, and in some cases HAPs speciation profiles were not available for a particular basin and/or source category. Thus, in these cases

certain HAP emissions in a number of basins were no t estimated, however the methodology is

available to estimate these emissions within the ca lculator tool should speciation data become

available.

Insufficient data was found to be available on ammo nia (NH 3 

### ) emissions from all oil and gas area sources, thus this pollutant was not estimated within the inventory.

Hydrogen Sulfide (H 2 

### S): Hydrogen sulfide emissions result from direct v enting of sour gas. Generally, molar concentrations of H 2 

### S in the gas are linked to the geographic location (basin) where the gas is produced. Data on produced gas H 2 

### S content is limited and not all gas analyses

include H 2 

### S. H 2 

### S emissions were estimated where data was available

.



## 4.3 Scope of Emission Sources

Emissions were estimated for upstream oil and gas s ector area sources including those during well drilling, completion (including fracing), prod uction and recompletion phases, and associated sources located at or in close proximity to the well pad. These numerous small sources are generally not tracked as part of major point source permitting programs, and may or may not be tracked as part of minor source permi tting programs (which vary from state to state). Source categories included in the inventor y are:

x Artificial Lift Engines

x Wellhead Compressor Engines

x Lateral Compressor Engines

x Drilling Rigs

x Condensate Tanks

x Hydraulic Fracturing Pumps

x Well Completion Venting

x Blowdown Venting

x Casing Gas Venting

x Dehydrators

x Pneumatic Devices

x Heaters

x Crude Oil TanksDecember 2012



### 16

x Produced Water Tanks

x Gas-Actuated Pneumatic Pumps

x Fugitive Emissions

x Mud Degassing

x Hydrocarbon Liquids Loading

x Flaring

This 2011 inventory builds off of the previous inve ntory for the Central states developed for CENRAP (Bar-Ilan, et al., 2008), and expands the sc ope of area source categories to gap-fill

those emissions that have often not been included i n past studies. These include emissions for mud degassing, produced water tanks, hydraulic frac turing pumps and casinghead gas venting. For source categories included in the original CENR AP study, new data or revisions to assumptions were incorporated as appropriate based on new data collected for this study. Examples of revisions to the CENRAP methodologies i nclude updating the component list assumptions for fugitive emissions to include compr essor seal fugitives. The current list of

sources was cross-referenced with a list of source classification codes (SCCs) to facilitate the transfer by states of emissions data from this work to the 2011 NEI.

Source categories in this inventory were divided in two major groups: “high-tier” sources and “low-tier” sources. High-tier sources refer to the most significant area sources of NOx, VOC and HAPs based on ENVIRON’s and ERG’s experience from p revious oil and gas area source inventory development studies and through discussio ns with CenSARA members. Major sources of VOC emissions in oil and gas operations are also significant sources of HAPs. Typically, oil and gas area sources are not large contributors to PM e mission inventories. Low-tier sources refer to other source categories included in the inventor y that are not considered high-tier. Table 4-1 lists the most significant sources of NOx, VOCs and HAPs emissions in the upstream oil and gas

sector.

Table 4-1. Major area sources of NOx, VOCs and HAP s in the upstream oil and gas sector.

Significant emissions source of

NOx VOCs and HAPs Artificial Lift Engines Crude Oil and Condensate Ta nks Wellhead Compressor Engines Well Completion Venting Lateral Compressor Engines Blowdown Venting Drilling Rigs Casing Gas Venting Hydraulic Fracturing Pumps Dehydrators

Pneumatic Devices



### Pollutant emissions for many source categories will vary according to the type of well (either gas or oil) since gas (or associated gas) compositi ons and process characteristics will differ according to the well type. For example, pollutants concentrations in fugitive leaks and any other venting emissions will vary between oil wells and gas wells, dehydrator equipment is mainly used in gas wells, casing gas venting is onl y applicable to oil wells, etc. Thus, anDecember 2012



### 17

enhanced methodology has been developed in this wor k to account for differences in emissions between well types by specifying basin-level and we ll-level calculation inputs, when feasible, and by applying more detailed production statistics to scale emissions such as oil versus gas well counts, horizontal versus vertical spuds, cond ensate production versus crude oil production, etc. as opposed to using more general s urrogates such as active well counts, spud counts and oil production.

While the sources analyzed here may not represent a complete list of all oil and gas area source categories, this study includes the most significan t area sources that contribute to the vast majority of emissions in a basin-level inventory ba sed on the technical team’s experience in development of oil and gas inventories. These sourc es are also the ones with the most complete set of input data that can be obtained thr ough literature review and survey efforts, thus decreasing the level of uncertainty in the emi ssions estimates. Sources that could not be included due to limited data availability were: sal t water injection engines, well pad construction equipment, workover equipment and some associated mobile sources. Associated on-road mobile sources operating in the well field such as service vehicles used during construction, drilling and production phases, are c aptured under some states’ mobile source

emissions inventories and are not included in this inventory.



## 4.4 Oil and Gas Activity Updates for the CenSARA Reg ion

4.4.1 Obtaining Oil and Gas Activity Data

A subtask in this project was to develop 2011 count y-level activity data of oil and natural gas upstream production and drilling activities for the CenSARA states. Typically, these data are available on oil and gas commission websites for ea ch state; however it is typically very cumbersome to obtain the data in this way as they a re presented in various formats and require significant processing to make them useable for inventory development. It is therefore advantageous to obtain as much information as possi ble from a single data source or clearinghouse in a standard format. ERG was able to make arrangements to obtain activity data for the 2011 base year from DrillingInfo’s HPDI dat abase for production wells (Drillinginfo, Inc. 2012). These data were supplemented by data obtaine d from state oil and gas commission websites and state-level drilling information from RigData.

Table 4-2 presents the activity data parameters use d to calculate oil and gas emissions. The derived level of aggregation is at the county-level . In total, there are 783 counties in the CenSARA oil and gas region (which does not include Iowa and Minnesota).December 2012



### 18

Table 4-2. County-level activity data parameters n eeded for emissions estimation.

Data Parameter

Oil Produced (barrels or BBL)

Natural Gas Produced (thousand standard cubic feet or MCF)

Condensate Produced (BBL)

Casinghead Gas Produced (MCF)

Oil Well Counts

Natural Gas Well Counts

Oil Well Completions

Natural Gas Well Completions

Produced Water at Oil Wells (BBL)

Produced Water at Gas Wells (BBL)

Spud Counts (Vertical, Horizontal, Directional)

Feet Drilled (Vertical, Horizontal, Directional)



### With the exception of Feet Drilled, all of the abov e parameters are reported fields in HPDI. “Feet Drilled” was estimated by calculating a “feet per drilling day” rate per well, which is roughly the well depth divided by the number of day s between the Completion Date and the Spud Date. This rate was then multiplied by the num ber of drilling days to obtain the “Feet Drilled” value. For wells that were spudded and co mpleted within 2011, the calculation was straightforward. For wells that began drilling prio r to 2011 and were completed in 2011 or began drilling in 2011 and were completed in 2012, only the portion of drilling occurring in

2011 was considered.

Table 4-3 presents the activity data sources for ea ch of the activity data parameters identified

in Table 4-2.December 2012



### 19

Table 4-3. Production and drilling data sources by state.

State

Abbreviation Oil/ Casinghead

Gas Production Natural Gas/

Condensate

Production Produced

Water Well Completions Spud Counts/ Feet

Drilled

AR 2011 HPDI 2011 HPDI 2011 HPDI Oil Gas Commission

Website 2010 HPDI; RigData

KS 2011 HPDI 2011 HPDI Not Available 2011 HPDI Kansas Corporation

Commission

Website

LA 2011 HPDI 2011 HPDI 2011 HPDI 2011 HPDI 2010 HPDI; RigData

MO 2011 HPDI 2011 HPDI Not Available 2011 HPDI 2010 HPDI; RigData

NE 2011 HPDI 2011 HPDI 2011 HPDI 2011 HPDI 2011 HPD I

OK 2011 HPDI 2011 HPDI Not Available Oil Gas Commission

Website 2010 HPDI; RigData

TX 2011 HPDI 2011 HPDI 2011 HPDI 2011 HPDI 2010 HPDI; RigData



### HPDI was the source for all the oil, casinghead gas , natural gas, and condensate data for 2011. Additionally:

x Produced water data were available in HPDI for Arka nsas, Louisiana, Nebraska, and Texas.

Produced water data were not available in HPDI or f rom the states for Kansas, Missouri and

Oklahoma.

x Well completions were available for 2011 in HPDI fo r Kansas, Louisiana, Missouri, Nebraska, and Texas. For Arkansas and Oklahoma, well completi on counts were obtained from their respective Oil and Gas Commission websites.

x Spud Counts and Feet Drilled were only available fo r 2011 in HPDI for Nebraska. For Kansas, spud counts and feet drilled were obtained from the Kansas Corporation Commission, Oil

and Gas Conservation Division website. For Arkansas , Louisiana, Missouri, Oklahoma, and Texas, the 2010 feet drilled from HPDI were scaled to 2011 using state-level well starts for each state obtained from RigData.

4.4.1.1 DrillingInfo Database in HPDI

The first data source for obtaining activity data w as information from HPDI’s DrillingInfo. This subscription-based information source extracts well -level data from state oil and gas commission websites. The data, while publically ava ilable, are periodically extracted from each commission website, and prepared in a standardized format. As part of EPA’s Enforcement Activities, an HPDI annual subscription is purchase d allowing data downloads, or “refreshes”, to be obtained throughout the year. In accordance with the licensing agreement, well-level data is proprietary, but derived products, such as aggregat ion at the county-level, are acceptable for public dissemination. EPA granted authorization of this derived data processing file for CenSARA’s use to support this project. For the CenS ARA states, there are over 2 million welllevel data records.December 2012



### 20

ERG extracted well identification (HPDIHeader), pro duction (HPDIProduction), and test (HPDIWellTest) information for onshore wells and le ases. Table 4-4 provides details on the available data by state, as of the refresh date. Ta ble 4-4 also includes the update frequency of the data by state and those states with available t est data.

Table 4-4. HPDI data coverage by state.

State

Abbreviation Production Group Update
Frequency Latest Production Data Test Data

Available

AR Well Monthly 4/1/2012 No
KS Lease Monthly 3/1/2012 No

LA Well/Unit a Monthly 5/2/2012 Yes

MO Lease Yearly 1/1/2012 No

NE Well Monthly 3/1/2012 No

OK Well Monthly 3/1/2012 No

TX Oil – Lease;

Gas – Well Twice Monthly 5/1/2012 Yes

a Louisiana Department of Natural Resources defines a unit as the “surface area that encompasses part o f or the entirety of a

reservoir.”



### ERG imported all of the data from HPDI into an Orac le database for processing. The Oracle database combines and processes all of the download files into one table of all production wells for the EPA Enforcement Universe Database. The proc essing steps are discussed below.

1) Combine Annual Production and Descriptive Informati on : For each entity 3 

### , ERG combined the annual production with the descriptive information (e.g., API number, lease name, location, operator, completion date, spud date, latest production date) from the HPDIHeader table to creat e the Wells table for the EPA Enforcement Universe Database. Appendix B prese nts the names and descriptions of the fields included in the Wells ta ble.

2) Remove Duplicate Wells : HPDI includes duplicate information for wells in some states because the data are stored by completion zo ne rather than at the well or lease level. Because all of the other descriptive d ata in HPDI are at the well or lease level, ERG combined duplicate API numbers (i. e., well bore identifiers 4 

### ) into a single record to avoid over counting wells. ERG excluded the records with missing API numbers (i.e., API_NO is null) from thi s “remove duplicate well” step. This could result in some over counting of wells, b ut this should be minimal

3 HPDI assigns a unique number to each property (i.e ., lease, well, unit) in the ENTITY_ID field.

4 API numbers are up to 14 digits long and are broke n into four segments. The first two digits correspo nd to the state; the next three digits correspond to the coun ty in the state. The next five digits are the uniqu e well identifier for the county. The next two digits are for the dir ectional side tracks (i.e., horizontal or direction al drills that each have different bottom hole locations), with 00 repr esenting the original well bore. The last two digit s are the event sequence code that distinguish between original com pletion, reentries, recompletion, and hole deepenin gs. Some states do not assign directional side tracks or eve nt sequence codes.December 2012



### 21 because a limited number of wells/leases did not ha ve API numbers and there were a small percentage of duplicate wells identifi ed. 5



### 1) Create Updated Active Status Flag (ACTIVE_FLAG) : ERG created an updated active status flag (ACTIVE_FLAG) using the latest p roduction date (LAST_PROD_DATE) after determining that HPDI’s stat us flag (STATUS) was not always accurate as part of the 2011 version of the Universe Database. 6



### 2) Create Production Flags (PROD09_FLAG, PROD10_FLAG, PROD11_FLAG) : ERG created production flags to identify miscellaneous well types (e.g., injection, observation, abandoned, pressure maintenance, N/A) that have oil and gas production in 2009 (PROD09_FLAG), 2010 (PROD10_FLAG ), and 2011 (PROD11_FLAG). The production flag is “Yes” if the annual oil or gas production is greater than zero.

3) Assign Each Well as Oil or Gas : Each well was reviewed to determine whether it should be labeled as an oil or a gas well. As such, the following hierarchy was

used:

a. HPDI designations of oil or gas b. Wells that had 2011 oil production, but no 2011 n atural gas production were assigned as “oil” wells; c. Wells that has 2011 gas production, but no 2011 o il production were assigned as “gas” wells; and d. Wells that had both 2011 oil and gas production w ere assigned “oil” or “gas” based on converting the oil and gas productio n data into BTU and selecting the larger of the two.

4.4.1.2 State Oil and Gas Commission Websites

To fill in missing data not available in HPDI, the state oil and gas commission websites were searched and the following data were used:

x 2011 well completions for Arkansas wells were obtai ned from the Weekly Reports found in

the Arkansas Oil and Gas Commission website (http://www.aogc.state.ar.us/permitreportarch.htm) and were summed to each county

x 2011 spud counts and feet drilled for Kansas wells were obtained from the Kansas Oil and Gas Commission website (http://www.kgs.ku.edu/PRS/O ra_Archive/ks_wells.zip) and summed to each county

x 2011 well completions for Oklahoma counties were ob tained from the Oklahoma Oil and Gas Commission website (http://www.occeweb.com/og/2 011%20Annual%20Report.pdf).

5 Duplicate wells in states with missing API numbers could be identified using the permit number, which should be unique for each well.

6 ERG found some wells with an “Active” STATUS had n ot produced in a number of years, while some wells with an “Inactive” STATUS had production data for 2010.December 2012



### 22

4.4.1.3 RigData
Drilling data in HPDI for 2011 was sparse, with onl y 2011 information from Nebraska available. As such, 2011 estimates needed to be generated for the remaining states. We used RigData (http://www.rigdata.com) as a source of Well Starts by year. The 2010 spud counts and feet drilled in HPDI for Arkansas, Kansas, Louisiana, Mi ssouri, Oklahoma, and Texas were adjusted by

the ratio of wells starts from 2010 to 2011 for eac h of these states.

4.4.2 CenSARA Oil and Gas Production Statistics for 2011
A summary of the resulting oil and gas production s tatistics by basin obtained through the HPDI database is presented in Table 4-5. This includes s ome key activity indicators such as natural gas production, casing head gas production, crude oil p roduction, condensate production, gas well and oil well counts, and water production. Statisti cs at the county-level and by well type for each surrogate are included in the Emissions Calcul ator Tool developed in this work. Production statistics were used as scaling surrogates for esti mating emissions at a county level. Surrogate

values extracted from HPDI have detail at the well- level; for example, the classification of well counts, water production, spud count, well completi ons and production is separated by well type (gas or oil). This allows regional scaling of emissions for a particular source category by capturing the difference in speciation of emissions which is affected by pollutant concentrations in the gas and by operational parame ters characteristic of each well type. It is important to note that produced water information i n the HPDI database were available only for four of the seven oil and gas producing states in CenSARA (Nebraska, Arkansas, Texas and Louisiana). Therefore, basin-wide water production numbers are not always representative of

the basin total as several basins are located in mo re than one state, including those for which water production was not available.December 201223Table 4-5. Basin-wide production statistics for the CenSARA region.BasinCrude OilProduction(bbl/yr)CondensateProduction(bbl/yr)Casinghead GasProduction(MCF/yr)Natural GasProduction(MCF/yr)Oil Well CountGas Well CountProduced water(bbl/yr)*Anadarko Basin38,849,50923,404,233128,500,5101,667,680,73127,04867,32363,229,429Arkoma Basin1,209,675105,7761,192,0531,566,638,4911,87118,341-Bend Arch-FortWorth Basin27,124,1673,711,76790,863,2342,087,999,22153,31225,082756,141,538Cambridge ArchCentral KansasUplift17,441,133938,882-10,535,45926,1952,60135,704,420Cherokee Platform9,221,921782,27010,409,412103,922,91628,78215,622-Denver Basin393,004751,19135,4981,165,03610677512,254,436East Texas Basin15,402,8246,062,20318,305,8011,839,495,35221,34223,326398,204,370Forest City Basin1,328,52517,874-277,4437,6442883,726,059Illinois Basin---2,573,300-24-LouisianaMississippi SaltBasins14,780,5022,150,51616,345,4482,505,781,19418,10117,316522,274,052Marathon ThrustBelt4,06482,300161,21641,565,72613675577,272Nemaha Uplift4,619,5741,077,95210,359,92523,190,0019,9162,192-Ozark Uplift-------Palo Duro Basin3,561,69681,5662,693,53818,964,4191,8181,08232,039,947Permian Basin299,041,3455,683,488669,798,454529,029,342145,54420,2953,226,217,276December 201224BasinCrude OilProduction(bbl/yr)CondensateProduction(bbl/yr)Casinghead GasProduction(MCF/yr)Natural GasProduction(MCF/yr)Oil Well CountGas Well CountProduced water(bbl/yr)*Salina Basin272,9248,187-6914931181,834Sedgwick Basin3,063,1741,523,188-36,776,2105,4173,401-SouthernOklahoma9,376,8801,930,87420,170,91977,555,3189,2563,037-Western Gulf144,929,90661,146,973311,480,9302,101,896,69545,43925,9231,489,520,630CenSARA RegionTotal590,620,823109,459,2401,280,316,93812,615,047,545402,297227,3046,540,071,263*Produced water is not representative of each basin's total since water production statistics were not available for every state. Water production was available for AR, LA, NEand TX only.December 2012



### 25

Table 4-6 shows the distribution of the production levels by state and within the basin portion

of each state.

Table 4-6. Summary of production, well counts and spud count by state and basin for

CenSARA.

State Basin Crude Oil

Production (bbl/yr) Natural Gas

Production (MCF/yr) Active Well

Counts Total

Spuds

Arkansas Arkoma Basin - 1,070,434,560 7,976 859

Illinois Basin - 2,573,300 24 - Louisiana-Mississippi Salt

Basins 5,154,192 4,577,320 2,485 187

Ozark Uplift - - - -

State Total 5,154,192 1,077,585,180 10,485 1,046

Kansas Anadarko Basin 11,917,770 223,851,902 33,672 676

Cambridge Arch-Central Kansas Uplift 16,996,535 9,756,144 28,375 808

Cherokee Platform 1,885,177 40,742,354 22,524 780

Forest City Basin 1,199,139 277,443 7,873 761

Nemaha Uplift 1,758,271 250,264 6,890 102

Salina Basin 272,924 691 494 22

Sedgwick Basin 3,063,174 36,776,210 8,818 257

State Total 37,092,990 311,655,008 108,646 3,406

Louisiana Louisiana-Mississippi Salt

Basins 9,626,310 2,501,203,874 32,932 520

Western Gulf 49,454,095 351,991,634 5,510 101

State Total 59,080,405 2,853,195,508 38,442 621

Missouri Cherokee Platform 27,401 - 5 -

Forest City Basin 85,409 - 29 -December 2012



### 26

State Basin Crude Oil

Production (bbl/yr) Natural Gas

Production (MCF/yr) Active Well

Counts Total

Spuds

Illinois Basin - - - -

Ozark Uplift - - - -

State Total 112,810 - 34 -

Nebraska Cambridge Arch-Central

Kansas Uplift 444,598 779,315 421 35

Denver Basin 393,004 1,165,036 881 6

Forest City Basin 43,977 - 30 12

Nemaha Uplift - - - -

Salina Basin - - - -

State Total 881,579 1,944,351 1,332 53

Oklahoma Anadarko Basin 12,337,317 816,787,833 32,765 243

Arkoma Basin 1,209,675 496,203,931 12,236 93

Bend Arch-Fort Worth

Basin 151,100 - 143 4

Cherokee Platform 7,309,343 63,180,562 21,875 96

Nemaha Uplift 2,861,303 22,939,737 5,218 31

Palo Duro Basin 58,349 782,668 141 -

Southern Oklahoma 9,376,880 77,555,318 12,293 19

State Total 33,303,967 1,477,450,049 84,671 486

Texas Anadarko Basin 14,594,422 627,040,996 27,934 565

Bend Arch-Fort Worth

Basin 26,973,067 2,087,999,221 78,251 1,530

East Texas Basin 15,402,824 1,839,495,352 44,668 629December 2012



### 27

State Basin Crude Oil

Production (bbl/yr) Natural Gas

Production (MCF/yr) Active Well

Counts Total

Spuds

Marathon Thrust Belt 4,064 41,565,726 688 8

Palo Duro Basin 3,503,347 18,181,751 2,759 19

Permian Basin 299,041,345 529,029,342 165,839 2,201

Western Gulf 95,475,811 1,749,905,061 65,852 1,570

State Total 454,994,880 6,893,217,449 385,991 6,522

CenSARA Region Total 590,620,823 12,615,047,545 402,297 227,304



### A significant amount of upstream oil and gas emissi ons occur during drilling; these emissions will be affected by the operational characteristics of the type of well drilled. The HPDI database provides a highly detailed breakdown of the drillin g activity, which separates the main activity drivers (spud count and feet drilled) by well type (gas or oil) and by wellbore type (horizontal or vertical wells). This allows for application of dif ferent emissions rates depending on the type of

well and wellbore and it also enables a better allo cation of the drilling activity that likely involves hydraulic fracturing techniques.December 201228Table 4-7. Summary of drilling activity by basin.BasinSpud CountTotal Vertical Feet DrilledTotal Horizontal Feet DrilledWell CompletionsAnadarko Basin 1,484 5,350,4396,014,4141,544Arkoma Basin 952 99,0814,311,8291,327Bend Arch-Fort Worth Basin1,534 1,129,252 9,850,8541,802Cambridge Arch-Central Kansas Uplift8433,086,133-232Cherokee Platform876 1,004,61760,137438Denver Basin643,645-7East Texas Basin6292,696,3454,731,632530Forest City Basin773598,428-43Illinois Basin----Louisiana-Mississippi Salt Basins7071,340,2284,675,1041,477Marathon Thrust Belt889,113--Nemaha Uplift133 490,56354,484192Ozark Uplift----Palo Duro Basin1978,88011,03413Permian Basin 2,201 18,911,1102,184,5341,706Salina Basin2272,212-5Sedgwick Basin2571,209,269-44Southern Oklahoma19 63,827 118,125350Western Gulf 1,671 4,845,45311,352,4792,006CenSARA Region Total12,134 41,108,59343,364,62611,716December 2012



### 29



## 5.0 INPUT DATA GATHERING

This section describes the different sources of inf ormation used to gather activity inputs used to estimate oil and gas area source emissions. Input d ata include the fractional usage of equipment at well-sites, properties of the equipmen t such as size, annual usage hours, emissions controls and emissions factors, process c haracteristics such as venting rates and well component counts, and chemical composition analyses used to determine pollutant emission rates. An attempt was made to obtain basin-specific input data applicable to each source category listed in Section 4.3. Where basin-specifi c data were unavailable, national averages or other available regional data were used, particular ly for estimating emissions from lower-tier source categories. CenSARA member states will be a ble to update this information in future inventories using the emissions calculator tool dev eloped in this study if more detailed data is

available in the future.

Three different approaches were used to obtain data on equipment and process activities:

1) Conduct new industry surveys of oil and gas opera tors within the CenSARA region,

2) Review oil and gas equipment and activity dataset s developed by state agencies and state facility permits and

3) Obtain information from existing studies or use a verages from survey data from various

basins in CenSARA.

These three approaches are described in more detail below.



## 5.1 Industrial Surveys

In the anticipation that not all information necess ary to estimate 2011 emissions for the selected area source categories would be available through state agency datasets and existing literature, a limited industrial survey was conduct ed to gather representative data at the basin level on field equipment and operations for the hig her tier oil and gas source categories. The survey effort was targeted at the major oil and gas producers operating in each basin within the CenSARA region. It has been ENVIRON’s experience wi th previous regional emissions inventories, such as the Rocky Mountain States oil and gas inventories prepared for the Western Regional Air Partnership (Bar-Ilan et al., 2008), that direct surveys of oil and gas operators are needed to properly characterize equip ment, well configuration, usage, processes,

and emissions factors.

5.1.1 Geographical Scope

ENVIRON narrowed the geographical scope of the surv ey outreach to the major oil and gas producing basins of particular interest to CenSARA states. For example, the Texas Commission on Environmental Quality (TCEQ) indicated that they were mainly interested in developing new data for the Permian Basin as they already have an established methodology and inputs for estimating oil and gas emissions in other basins wi thin the State. Louisiana Department of Environmental Quality (LADEQ) requested that the su rvey focus on activities in the northern portion of the state where potential air quality is sues in the area of Baton-Rouge could beDecember 2012



### 30

focused on, thus the Louisiana-Mississippi Salts Fl ats basin was of particular interest to them. Discussions with Oklahoma, Arkansas and Kansas dete rmined that survey efforts would focus on areas where the bulk of the production occurs wi thin each of these states, including the Anadarko, Arkoma and Cambridge Arch-Central Kansas Uplift basins. Cambridge Arch is also a major oil and gas producing region in Nebraska. Thu s, surveys were developed to gather data for the following basins:

x Anadarko Basin

x Arkoma Basin

x Louisiana-Mississippi Salt Basins

x Cambridge Arch-Central Kansas Uplift

x Sedgwick Basin

x Permian Basin

Information in the survey was specifically requeste d at the basin level and for calendar year 2011. As part of the survey, operators were asked to list the counties within each basin where they have operations in order to verify the proper region to apply the data being collected.

5.1.2 Survey Description and Development

The survey effort was focused on collecting field d ata on the most significant area sources of NOx, VOC and HAPs referred to here as “high-tier” s ource categories and listed in Table 4-1. These sources can have a high variability in emissi ons and operation parameters across different basins, hence estimates for these sources benefit from industry data at the basin level. A worksheet format survey form was prepared for each targeted operating company to

fill out and return in electronic format. The surve y design was based on previous oil and gas inventory surveys used in the IPAMS/WRAP Phase III oil and gas emission inventory development project (Bar-Ilan et al., 2008). The su rvey consisted of various tabs requesting information for each of the high-tier source catego ries, as well as an introductory tab describing the purpose of the survey, the regional scope, and instructions for filling in the requested information. Another tab gathered/confirmed contact information of the surveyed company and allowed them to enter the counties of operation and any notes or comments on the data provided. The set of survey forms used in this stud y are included as electronic Appendix D.

Each source category tab requested basic informatio n needed to determine input values for basin-level emissions calculations. Among the data fields included were equipment counts, hours of operation, horsepower, load factors, firin g rates, emissions factors, engines configuration for drilling rigs, venting rates and event counts for venting categories, well configuration for pneumatics and fugitives, and inf ormation on emissions controls such as control method, fraction controlled and control eff iciency. Where appropriate, data was requested by well type to account for differences b etween oil and gas wells in equipment configurations, venting rates and emissions factors . Each survey also requested information on gas composition analyses of produced gas by well ty pe (gas or oil), necessary to estimate VOC, HAPs, methane (CH 4 

### ), and hydrogen sulfide (H 2 

### S) emissions for venting/leaking sourceDecember 2012



### 31

categories based on the pollutants concentrations i n the gas. Operators were asked to provide any supplemental documents to aid in emissions calc ulations including: input and output files from emissions models such as EPA TANKS, E&P Tank a nd GRI-GlyCalc; equipment inventories for compressor engines, drill rigs, and artificial lifts; and copies of produced gas composition analyses.

5.1.3 Survey Outreach Process and Results

ENVIRON analyzed oil and gas production by operator for 2011 from the HPDI database and state oil and gas commission records and developed a list of the top oil producing and top gas producing companies in each basin. Production owner ship varied considerably by basin for oil and gas, thus a recommended list of selected compan ies for the survey outreach was developed based on the representation of at least 5 0% ownership of production (both oil & gas) within each basin or the selection of the top 10 companies (in the case they had at least 50% ownership). This resulted in a comprehensive li st of 127 oil and gas companies recommended for survey. ENVIRON has developed worki ng relationships with many major oil and gas companies, particularly through ongoing oil and gas emissions projects such as the IPAMS/WRAP Phase III (Bar-Ilan et al., 2008). ENVIR ON and CenSARA state agencies worked together to establish contacts at selected companie s for which ENVIRON did not already have a

suitable contact. Between the collaboration of ENV IRON and CenSARA members, a list of contacts for 82 companies was compiled; individual (non-generic) contacts for 45 operators out of the 127 selected could not be identified during the survey outreach effort. Subsequently, CenSARA or state agencies sent each company contact within their jurisdiction an introductory letter explaining the purpose of the survey, its im portance to the operator and to the state agencies, and requesting their cooperation in respo nding to the survey request in a timely

manner.

ENVIRON sent electronic surveys to each of the 82 c ompanies for which an electronic contact

was available. The email communication included a s urvey form for each of the basins in which the company was a significant oil and gas operator. Thus, several companies such as Chesapeake Operating, Inc. and XTO Energy, Inc. rec eived requests to fill two to three surveys, one for each basin where they have operations, yiel ding a total of 99 surveys that were sent out among the top oil and top gas producing companies o f the CenSARA region. A window of 30 calendar days was given to the companies to fill-in the surveys, with a subsequent extension of 1-2 weeks for some companies that requested it. Ele ven (11) companies sent responses stating that they declined to participate; the most frequen t explanation for declining was lack of resources to fill-in the survey at the time of requ est due to concurrent requirements to complete national Subpart W GHG inventory reporting to the EPA. Twenty-one (21) companies agreed to participate, resulting in 29 surveys (out of 99) filled by operators/contractors and
returned to ENVIRON; these are shown in Table 5-1. The remaining 50 companies contacted did not respond to any communications. Survey response rates by basin are summarized in Tables

5-2.December 2012



### 32

Table 5-1. Participating companies in the survey o utreach effort.

Company Name Basin of Major Operation Baird Oil Company LLC Cambridge Arch-Central Kansas Uplift

BHP Billiton Arkoma

Bonanza Creek Louisiana-Mississippi Salt Flats

Chaparral Energy Anadarko

Chesapeake Energy Anadarko, Arkoma

ConocoPhillips Anadarko

Edmiston Oil Company, Inc Sedgwick, Cambridge Arch- Central Kansas Uplift

John O. Farmer Inc Cambridge Arch-Central Kansas Up lift

Merit Energy Anadarko

Murfin Drilling Company Inc Cambridge Arch-Central K ansas Uplift

Noble Energy, Inc Cambridge Arch-Central Kansas Upl ift

Priority Oil and Gas, LLC Cambridge Arch-Central Ka nsas Uplift

Ritchie Exploration Cambridge Arch-Central Kansas U plift, Anadarko

Sheridan Production Company Arkoma

Southwestern Energy Company Arkoma

Stephens Production Company Arkoma

Trans Pacific Oil Anadarko, Cambridge Arch-Central Kansas Uplift, Sed gwick

Vess Oil Corporation Cambridge Arch-Central Kansas Uplift

Whiting Oil and Gas Corporation Anadarko, Louisiana -Mississippi Salt Flats

Woolsey Operating Co, LLC Sedgwick

XTO Energy Anadarko, Louisiana-Mississippi Salt Flat s, Permian



### Table 5-2. Summary of survey responses and ownersh ip of responses by basin.

Basin Surveys

Sent Surveys

Returned Percent

Response Basin-wide Gas

Production Ownership of Respondents (%) Basin-wide Oil

Production Ownership of Respondents (%)

Anadarko Basin 26 7 26.9% 21.1% 18.4%

Arkoma Basin 17 6 35.3% 68.5% 32.5%

Louisiana-Mississippi

Salt Basins 13 3 23.1% 2.4% 15.7%

Cambridge Arch-Central
Kansas Uplift 18 9 50.0% 38.0% 16.7%

Sedgwick Basin 15 3 20.0% 13.1% 11.8%

Permian Basin 10 1 10.0% 4.1% 2.6%

Total 99 29 29.3%



### Table 5-2 shows the production ownership of the sur vey respondents in each basin. This percent ownership provides a qualitative assessment of the level of basin-wide representation that was achieved from the survey effort. Ideally, if most surveyed companies had participated, 50-90 percent of basin production would have been r eflected in the returned surveys. TheDecember 2012



### 33

largest number of responses was obtained from small -to-large operators in the Cambridge Arch Basin, and two major gas producers (Priority and No ble Energy) responded to the survey, representing 38% of basin-wide gas production in th e Cambridge Arch. Although responses were limited, the Arkoma basin was well represented for gas production and to a lesser extent for oil production as a result of the participation of key players such as Sheridan and Southwestern Energy. Although several responses for the Louisiana-Mississippi Salt Basins were received for oil producers, it should be noted that the surveys were intentionally not sent to the major gas producers in the basin as they were part of the recent Haynesville Shale emissions study described below in the literature review. Ov erall, the percent response from operators within all the basins was lower than desired, parti cularly for oil companies in the Permian Basin, the largest oil producing region in Texas, for whic h only one response was returned.

Survey data from responding companies were evaluate d for quality, applicability and usefulness. Returned surveys were not consistently filled for all source categories. For some basins, sufficient and useful data was collected fr om survey responses for many of the source categories, and for other basins/source combination s, very little useful data was provided in the surveys. Criteria for evaluating surveys were:

x Quality of data: survey responses were assessed for quality to determine if specific data were beyond the typical range of values for a param eter based on ENVIRON’s experience from previous oil and gas survey efforts or in comp arison to other data sources. In cases of specific responses of questionable quality, ENVIRON made efforts to further examine the data by contacting the surveyed company and asking for further clarification on the data provided. ENVIRON also examined the company’s level s of operation to evaluate if it would warrant any unusually high or low level of activity for particular data fields. Data that were determined to lie well outside a typical range with out a reasonable explanation were rejected from inclusion in the final compilation. I ncidences of this were isolated to a few responders.

x Applicability and usefulness: This relates to data that were provided in a different format or were simply incomplete and could not easily be conv erted or assigned to representative equipment and process input data required by the me thodology. For example, for a particular basin there was a single response for la teral compressor engines which applied to an electric compressor from one small operator. Thi s data could not be assumed to be representative of the entire basin’s usage of later al compressors and thus was not used. On occasion, useful and representative data were provi ded in different formats that allowed the estimations of emissions for a particular sourc e by converting the data to the desired format or making changes to the methodology.

Each data field gathered from survey responses was averaged primarily by basin, by well type when applicable, and by any other breakdown relevan t to the source category; for example drilling rig data were averaged by horizontal and v ertical configurations of drill rigs. When applicable and when sufficient data were available, the weighted average of some data fields was estimated using operator-production surrogates (gas production, oil production, well counts) that were available from the HPDI data. For example, the data field “fraction of wellsDecember 2012



### 34

with wellhead compressors” was provided by groups o f companies within a few basins, and the final input was derived from the weighted average b ased on operator well counts to arrive at a more representative value for the basin.



## 5.2 State Permit Data Review

5.2.1 Minor Source Permits
Each state’s Air Quality Division (or equivalent ag ency) has a set of air permitting programs that may or may not cover a number of oil and gas area s ources. Minor source permits are typically a sub-classification of construction or operating p ermits required for new and modified minor sources. A minor source is any source that emits le ss than a major source threshold. Some states have a broad scope of sources and/or facilit ies that are subject to this type of permit, covering facilities such as oil and gas well-sites (often termed production facilities), where many of the oil and gas area sources are located. Other states’ permitting programs focus on major sources and only cover minor sources located at oil and gas downstream facilities (e.g. gas plants, compressors on transmission lines) that wou ld generally not qualify as an area source

category.

Some data fields that could not be collected throug h survey responses were derived from permit applications from states’ minor (or syntheti c minor) source permitting programs such as those of Oklahoma, Kansas and Louisiana. In these s tates, oil and gas facilities, including new and modified well sites, require a construction and /or operating permit application that

includes the calculation of emissions from minor so urces at the facility; these may include: well heaters, condensate/crude oil tanks, wellhead compr essor engines, artificial lift engines, dehydrator units, fugitives, flaring, liquids loadi ng, and other engines located on site. Many of these “minor” sources are typically classified as a n oil and gas area source category. Thus, data from minor source permits can be useful for the est imation of area source emissions. A caveat in utilizing permit data is that emissions estimate s for permit applications are often based on conservative assumptions to reflect the highest lev el of emissions achievable by a facility or the potential to emit (PTE). It should also be noted th at minor sources located further downstream in the oil and gas process than a well site (such a s a tank battery or compressor station) may not represent activity at the well site. Neverthel ess, minor source permit data were useful for gap-filling many data fields for source category/ba sin combinations with regionally-specific

information that was not otherwise available from t he survey responses or other data sources. Permit applications for ‘production facilities’ (we ll sites) denote the county where the facility is located, thus providing a way for allocating the ac tivity data to the basins of interest, i.e., Louisiana Mississippi Salt Flats, Anadarko and Arko ma, Cambridge and Sedgwick.

5.2.2 Permit Data Mining Procedure and Examples

CenSARA member states worked with ENVIRON to provid e access to hard copies of minor source permit applications for production facilitie s that required a 2011 permit. Oklahoma members provided access to a library of CY2011 synt hetic minor source permit applications for production facilities at Anadarko and Arkoma. Data was pulled from 25 permits for sourceDecember 2012



### 35

categories of interest including compressor engines , artificial lift engines, condensate tanks and

heaters.

Louisiana provided a comprehensive list of oil and gas related Agency Interest (AI) numbers, an identification number assigned to every facility re gulated by the Louisiana Department of Environmental (LADEQ,) and categorized under a sour ce industrial classification (SIC) code.

Production facilities were filtered from the AI dat abase based on the SIC codes for well sites, and sample applications were queried in LADEQ’s Ele ctronic Document Management System (EDMS) by the AI numbers. A bank of 30 permit appli cations were reviewed to extract emissions data for compressor engines, artificial l ift engines, condensate/oil tanks, and dehydrators in production facilities located in the Louisiana Mississippi Salt Flats basin. Examples of specific data fields that were extracte d from air permits and used as calculation inputs for source categories’ emissions are shown i n Table 5-3.

Table 5-3. Examples of specific data fields gap-fi lled by state permit data.

Source Category Data field(s) Comments on derivation of data
Condensate/oil tanks Heating value of flash gas; ta nklosses per unit throughput (lbsVOC/bbl) Tanks losses per unit throughput values were derive d by dividing annual uncontrolled tank emissions (flashing +w/b) by the liquid throughput of the tan k in barrels, and taking a throughput-based weighted average from all permits. Controls: fraction of tank throughput

flared

Dehydrators Still vent VOC emissions per unit of gas throughput (lbs-VOC/MMSCF); dehydrator reboiler BTU rating Still vent VOC emissions per unit throughput values were derived by dividing annual uncontrolled dehydrator emissions by the annual gas throughput i n MMSCF/yr. A throughput-based weighted average from all permits was used. Heaters Heater rating (MMBTU/hr) A weighted average from various permits was used.
Compressors (wellhead and lateral) Fraction of lean burn versus rich

burn OKDEQ provided an equipment inventory on compressor engines (minor sources) by basin; this inventory included equipment counts, engines characteristics such as size, rich vs. lean burn an d data

on controls. Fractions were estimated based on equipment counts and the categorization of interest

. Controls: fraction of rich burn engines controlled by non-selective catalytic reduction; fraction of lean burn engines controlled by catalytic

oxidizers



### In addition, Kansas and Oklahoma provided specific minor source permit data from their records to help gap-fill data fields for particular source categories. For example, condensate tanks and crude oil tanks emissions data (and emiss ions model runs if available) from permits were obtained to estimate an average VOC emissions factor for tank losses. E&P TANK model runs include the speciation of flash and post-flash gas streams that enabled estimation of HAPs emissions from tanks. Oklahoma also provided crucia l data on minor source compressor engines that allowed for the derivation of data fie lds such as percent of compressors controlled, and fraction of lean burn versus rich b urn.December 2012



### 36

Gas composition analyses for different gas venting/ leaking points at well sites, such as produced gas, flash gas, and post-flash gas, were a lso extracted from permit applications, or provided directly by state agencies (Kansas) for sp ecific basins. These were used to gap-fill any average gas compositions needed to estimate VOC and HAPs emissions from condensate/oil tanks flashing losses, tank unloading emissions, an d other venting sources.



## 5.3 Literature Sources and Gap-Filling for Non-Surve yed Basins

Regionally-specific inputs that could not be derive d from surveys or state minor source air permits were gap-filled with data from previous oil and gas emissions studies or, when considered necessary, using regional average values from survey data collected for other basins within CenSARA. This approach was used primarily bu t not exclusively for the low-tier source categories and for those basins that were not part of the survey outreach. ENVIRON and ERG reviewed existing sources of data in the literature on oil and gas activities and emission factors to fill in remaining data gaps in the inventory cal culation inputs.

5.3.1 Reviewed literature

Literature was reviewed for information applicable to oil and gas activities in the CenSARA

domain. Data sources were evaluated to determine wh ich data were most suitable for filling data gaps either for selected source category/basin combinations or, in some cases, for all basins for a low-tier source category. Criteria use d to determine the applicability of the literature data for the CenSARA oil and gas emissio ns inventory was based on: (1) the geographic scope of the study (2) temporal represen tativeness of the study and (3) quality/consistency of data as compared against oth er literature sources. The geographic scope

was the most critical criteria for selection of the data as equipment/process characteristics, emissions rates, and gas compositions vary by regio n. For example, preliminary data from the Haynesville Shale 2011 Emissions Inventory Update ( ENVIRON, 2012) was found to be the most relevant for certain source category estimates for the Louisiana-Mississippi Salt Flats Basin; the Haynesville Shale formation is located within the S alt Flats Basin and is where most of the basin-wide gas production is generated. Specific ca lculation inputs derived from the Haynesville Shale 2011 Emissions (Draft) Inventory are shown in Table 5-4, along with the other data

resources that were reviewed and from which data in puts were derived in this study. When warranted, the temporal characteristic of the data source was considered as a selection criteria to insure that the most up-to-date data were applie d in the calculations. Finally, data were evaluated for usefulness and consistency with simil ar oil and gas emissions inventory inputs and individual data points were either rejected or used based on ENVIRON’s experience with previous oil and gas inventory development projects

.December 2012



### 37

Table 5-4. Specific calculation inputs derived fro m literature sources.

Literature Source Geographic Domain of

Source Source Category/Basin

data was applied for Data Field(s) 2011 Update of the Haynesville Shale Emissions Inventory (ENVIRON, 2012). Draft Inventory as of

October 2012 Haynesville Shale

formation within the Louisiana Mississippi Salt

Flats basin Wellhead Compressors/Salt

Flats Fraction of lean burn vs. rich burn; rated horsepower for lean burn engines; load factors Controls: % of rich burn engines controlled by non-selective catalytic reduction Drill Rigs (Horizontal)/Salt

Flats Total horsepower and hours of operation from a diesel-powered drill rig (includes all equipment in rig)

Fracturing Pumps/Salt Flats Engine horsepower and load

factors

Recommendations for Improvements to

the CENRAP States’

Oil and Gas

EmissionsInventories (BarIlan, et al., 2008) Central Region States Drill Rigs/Permian Vertical and horizontal drill rig configurations (total HP, load factors)
Completion Well Venting/Permian Venting rate (MCF/event)

Heaters/OK, LA, TX basins Numbers of heaters per we ll; heater BTU rating Fugitives/all basins Number of devices per typical

well Condensate Tanks/Permian Controls: Fraction of tank throughput flared

EPA 2010 National

Greenhouse Gas
Inventory (EPA, 2012) National average Completion Well Venting/Sedgwick Venting rate volume (MCF/event)

National average Heaters/Kansas basins Numbers of heaters per well

Midcontinent Region Gas-actuated pneumatic Pumps/all basins Methane venting rate per unit gas throughput, Methane venting rate per kimray pump, average no. pumps per well Midcontinent Region Compressor seal fugitives/all basins Methane leaking rate from compressor seals (SCF methane/hr/compressor) National average Crude oil loading/all basins Fract ion of crude oil production delivered to refinery by truck

EPA Natural Gas Star Workshop on Plunger Lifts (EPA, 2006a) National average Blowdowns/AnadarkoArkoma Controls: Plunger lift control efficiency for liquids unloading

The Climate Registry

Oil and Gas

Production Annex II

to the General Reporting Protocol (TRC, 2010) National average Water tanks/Permian and

Salt Flats Methane emissions factor for water tank losses at gas wells;

methane emissions factors for

water tanks at oil wells Mud degassing/all basins Methane emissions factors fo r mud degassing; methodologyDecember 2012



### 38

Literature Source Geographic Domain of

Source Source Category/Basin

data was applied for Data Field(s)

EPA AP 42, Compilation of Air

Pollutant Emission Factors, Fifth Edition (EPA, 1991; EPA,
1995; EPA, 1998;
EPA, 2000; EPA, 2008) National average Compressor engines (wellhead and lateral)/all

basins Natural gas fired reciprocating engines emissions factors for rich burn and lean burn engines Artificial Lifts/all basins Natural gas fired reciprocating engines emissions factors for rich burn engines for all pollutants of

interest Flaring (all venting source categories)/all basins Flaring emissions factors for all criteria pollutants, greenhouse gases and formaldehydeHeaters/all basins External combustion natural gasfired engines emissions factors

Fugitives/all basins TOC emissions factors for each equipment type by service type(kg/hr/component) Loading/all basins Saturation factors and methodology for liquid loading

emissions

NONROAD2008a

emissions model (EPA, 2005) CenSARA states average Drill Rigs/all basins CenSARA regional average

emissions factors for 2011 for oil field equipment derived from EPA

NONROAD2008 model SPECIATE 4.0 (EPA, 2006b) National average Drill Rigs, Fracing Pumps, Flaring, Heaters/all basins Speciation profiles for HAPs in

combustion emissions from selected source categories

WRAP Phase III (WRAP, 2012) Rocky Mountain Region Drilling Rigs/Permian Engine t ime of operation

Crude Oil Tanks/Permian VOC emissions factor (lbsVOC/bbl)

Controls: fraction of tank throughput flared Dehydrator/Permian VOC emissions factor (lbsVOC/MMSCF)



### 5.3.2 Inputs for emissions estimates of non-surveyed basins

Inventory development in this study was focused on characterizing to the best extent possible emissions and activity in the major oil and gas pro ducing basins (based on 2011 production statistics) and on basins identified by CenSARA as being of special interest. Basin-specific data were collected via industry surveys and via review of minor source air permits as explained in previous sections. Part of the oil and gas activity data for most basins in Texas other than the

Permian and the Marathon Thrust Belt were obtained from the Texas statewide oil and gas inventory and its associated emissions calculator t ool previously developed by ERG (ERG, 2010). Data inputs for the following basins that were not included in the surveys were developed on a case by case basis:

x Bend Arch-Fort Worth Basin (TX, OK)December 2012



### 39

x Cherokee Platform (KS, OK)

x Denver Basin (NE)

x East Texas Basin (TX)

x Forest City Basin (MO, KS)

x Illinois Basin (MO, AR)

x Marathon Thrust Belt (TX)

x Nemaha Uplift (NE, KS, OK)

x Ozark Uplift (MO, AR)

x Palo Duro Basin (TX)

x Salina Basin (KS, NE)

x Southern Oklahoma (OK)

x Western Gulf (TX, LA)

For basins outside of Texas, such as Cherokee, Nema ha Uplift, Ozark Uplift, Salina, Southern Oklahoma, Denver, Forest City and Illinois, inputs for each emissions calculation field were developed based on regionally-specific averages (or equivalencies) of data used in other surveyed-basins’ calculations. Averages were compil ed differently for each non-surveyed basin based on what ENVIRON considered the most equivalen t region (or mix of regions) to represent activity in the non-surveyed basin. For example, da ta fields for Denver basin were assumed to be similar to those of the Cambridge Arch. The aver aging rules were applied consistently in each data field throughout all source categories in the inventory. Table 5-5 summarizes the averaging rules for input data for non-surveyed bas ins outside of Texas.

Table 5-5. Input data assumptions for non-surveyed basins outside of Texas (except Marathon Thrust Belt).

Non-surveyed basin Inputs were developed as Cherokee Platform Activity data is the average of a ctivity from surveyed basins (Anadarko, Cambridge, Arkoma, Permian and Louisiana Salt Flats)
Denver Basin Activity data assumed similar to that of Cambridge Arch Basin Forest City Basin Activity data is the average of C ambridge and Sedgwick Basins’ activity

Illinois Basin Activity data assumed similar to that of Arkoma Bas in Marathon Thrust Belt Activity data assumed similar t o that of Permian Basin Nemaha Uplift Activity data is the average of Cambr idge and Sedgwick Basins’ activity Ozark Uplift Activity data is the average of activi ty from surveyed basins (Anadarko, Cambridge, Arkoma, Permian and Louisiana Salt Flats)

Salina Basin Activity data assumed similar to that of Cambridge Arch Basin Southern Oklahoma Activity data is the average of A rkoma and Anadarko Basins’ activity



### Activity inputs in the Marathon Thrust Belt were as sumed to be equivalent to those in the Permian Basin. For non-surveyed basins in Texas oth er than the Marathon Thrust Belt, input data for certain source categories were derived fro m previous oil and gas inventories prepared for or by the Texas Commission on Environmental Qua lity (TCEQ) as shown in Table 5-6December 2012



### 40

including the Texas Statewide Oil and Gas Inventory (ERG, 2010) which estimated 2008 countylevel emissions for area sources in the upstream se ctor (on-shore). ERG collected county-level activity data, and specific emissions and emission factors data for each source category included in that inventory based on a variety of da ta sources, including existing databases (such as the Texas Railroad Commission (TRC) oil and gas production data), point source emissions inventory reports submitted to TCEQ (used for dehyd rators), vendor data (used for compression engines and artificial lift engines), a nd published emission factor and activity data from the Houston Advanced Research Center (HARC), t he Central Regional Air Planning Association (CENRAP), and the U.S. Environmental Pr otection Agency (EPA).

Table 5-6. Data sources used for calculation input s for non-surveyed basins in Texas

Study and General Description Author, Year Notes
TCEQ’s Characterization of Oil and Gas Production Equipment and Develop a Methodology to Estimate Statewide

Emissions ERG, 2010 Base year 2008 emissions inventory at the county-level for multiple oil and gas source categories. Includes emissions calculator

tool for Texas basins.
TCEQ’s Condensate Tank Oil and Gas Activities Study ERG, 2012 Developed emissions factors and control factors for condensate storage tanks. Data

is meant to be used for area source inventory development at the county-level for eight geographic regions in the TX.



### Data from these studies were applied to Texas’ basi ns using the methodologies developed for CenSARA to the extent possible. For those source c ategories that were not covered in previous Texas studies, calculation inputs were based on a r egional average using data from surveyedbasins. State agencies may choose to gather the nec essary data to update and provide more regionally specific inputs in the future.December 2012



### 41



## 6.0 EMISSIONS CALCULATOR TOOL DEVELOPMENT

6.1 Structure of Emissions Tool

The CenSARA Oil and Gas Emissions Calculations Tool is housed in a Microsoft Excel workbook. A separate workbook was developed for each state an d is used to compile emissions for only that state. These are included in Electronic Append ix C. The Calculator Tool design is similar to the emissions calculator tool previously developed by ERG for the TCEQ but is more robust and flexible to accommodate the large amount of data de veloped in this study and the needs of

each individual state. The Tool is structured to a llow users to enter either county- or basinspecific information and review the calculated emis sions. The “backbone” of the Tool consists

of three main data sheets:

x Inputs_Activity: county-level production and drilli ng information. There are 783 counties within the CenSARA oil and gas region;

x Basin_Factors: basin-level factors that apply to va riations in oil and natural gas activities

across each basin. There are 19 basins within the C enSARA oil and gas region. Approximately 400 data parameters describe each bas in and source category;

x Emission_Factors: applied to selected source catego ries, regardless of geographic level.

The information in the three main data sheets are a ctively linked to the SCC-specific emission calculation worksheets. In total, there are 34 work sheets representing 18 source categories. Table 6-1 presents the Source Categories and the ap plicable SCCs.

Table 6-1. Oil and gas emission source categories.

Source Category SCC SCC Shortened Description

ARTIFICIAL LIFT ENGINES 2310000330 Oil & Gas Expl & Prod /All Processes /Artificial Li ft

BLOWDOWNS 2310021603 On-Shore Gas Production / Gas Well Venting -

Blowdowns

CASINGHEAD GAS VENTING 2310011000 On Shore Crude Oi l Production All Processes

CONDENSATE TANKS 2310021010 On-Shore Gas Production /Storage Tanks:

Condensate

CRUDE OIL TANKS 2310010200 Oil & Gas Expl & Prod /Crude Petroleum /Oil Well Tanks - Flashing & Standing/Working/Breathing

DEHYDRATORS 2310021400 On-Shore Gas Production Dehydrators

DRILL RIGS 2310000220 Oil And Gas Exploration Drill Rigs FUGITIVES 2310011501 On-Shore Oil Production /Fugit ives: Connectors FUGITIVES 2310011502 On-Shore Oil Production /Fugit ives: Flanges

FUGITIVES 2310011503 On-Shore Oil Production /Fugitives: Open Ended

Lines

FUGITIVES 2310011505 On-Shore Oil Production /Fugitives: Valves FUGITIVES 2310021501 On-Shore Gas Production /Fugit ives: Connectors FUGITIVES 2310021502 On-Shore Gas Production /Fugit ives: Flanges

FUGITIVES 2310021503 On-Shore Gas Production /Fugitives: Open Ended

Lines

FUGITIVES 2310021505 On-Shore Gas Production /Fugitives: Valves FUGITIVES 2310021506 On-Shore Gas Production /Fugit ives: Other GAS-ACTUATED PUMPS 2310111401 On-Shore Oil Explorati on /Oil Well Pneumatic PumpsDecember 2012



### 42 Source Category SCC SCC Shortened Description

GAS-ACTUATED PUMPS 2310121401 On-Shore Gas Exploration: Gas Well Pneumatic
Pumps HEATERS 2310010100 On-Shore Oil Production /Heater Treater

HEATERS 2310021100 On-Shore Gas Production /Gas Well Heaters
HYDRAULIC FRACTURING 2310000660 Oil & Gas Expl & Pr od /All Processes /Hydraulic
Fracturing Engines LATERAL/GATHERING LINE

COMPRESSORS 2310021351 On-Shore Gas Production/Lateral Compressors 4 Cycle Rich Burn LATERAL/GATHERING LINE

COMPRESSORS 2310021251 On-Shore Gas Production/Lateral Compressors 4 Cycle Lean Burn

LOADING EMISSIONS 2310011201 On-Shore Oil Production /Tank Truck/Railcar Loading: Crude Oil

LOADING EMISSIONS 2310021030 On-Shore Gas Production /Tank Truck/Railcar Loading: Condensate

MUD DEGASSING 2310111100 On-Shore Oil Exploration /Mud Degassing

MUD DEGASSING 2310121100 On-Shore Gas Exploration /Mud Degassing

PNEUMATIC DEVICES 2310010300 Oil Production Pneumati c Devices

PNEUMATIC DEVICES 2310021300 On-Shore Gas Production Pneumatic Devices

PRODUCED WATER 2310000550 PRODUCED WATER

WELL COMPLETIONS 2310111700 On-Shore Oil Exploration: Oil Well Completion: All

Processes

WELL COMPLETIONS 2310121700 On-Shore Gas Exploration: Gas Well Completion: All

Processes

WELLHEAD COMPRESSOR

ENGINES 2310021202 On-Shore Gas Production /Natural Gas Fired 4Cycle
Lean Burn Compressor Engines 50 To 499 HP

WELLHEAD COMPRESSOR

ENGINES 2310021302 On-Shore Gas Production /Natural Gas Fired 4Cycle Rich Burn Compressor Engines 50 To 499 HP



### At the request of the technical team, three new SCC s were generated by EPA relating to specific source categories. They include:

x Tool Source Category: Hydraulic Fracturing

o New SCC: 2310000660

o SCC Shortened Description: Oil & Gas Expl & Prod /A ll Processes /Hydraulic Fracturing
Engines

o Comment: This SCC replaces 2270010010; while this i s a valid SCC description (Diesel: Industrial Equipment: Other Oil Field Equipment (Dr illing Rigs)), the SCC is under the NONROAD Sector, and would need to be submitted sepa rately from the other Nonpoint source oil and natural gas source categories. To av oid generating two separate EIS submittal files, EPA created a new nonpoint SCC cod e to describe this emission source.

x Tool Source Category: Lateral/Gathering Compressors – 4-Cycle, Lean Burn

o New SCC: 2310021251

o SCC Shortened Description: On-Shore Gas Production/ Lateral Compressors 4-Cycle Lean

BurnDecember 2012



### 43

o Comment: This SCC replaces 2310021209, which is “On -Shore Gas Production/ Total: All Natural Gas Fired 4-Cycle Lean Burn Compressor Engi nes”. This description is too general and not specific enough for this source cat egory.

x Tool Source Category: Lateral/Gathering Compressors – 4-Cycle, Rich Burn

o New SCC: 2310021351

o SCC Shortened Description: On-Shore Gas Production/ Lateral Compressors 4-Cycle Rich

Burn

o Comment: This SCC replaces 2310021309, which is “On -Shore Gas Production/ Total: All Natural Gas Fired 4-Cycle Rich Burn Compressor Engi nes”. This description is too general and not specific enough for this source category.

Each SCC worksheet follows the same general structu re. The first nine columns contain descriptive information related to the emissions es timate, and are: FIPS, State abbreviation,
County Name, Attainment status, Basin Name, SCC, SC C Shortened description, Source Category name, pollutant code. The next sets of fie lds are information extracted from the “Inputs_Activity” tab, such as: oil counts; gas com pletions; and horizontal drilling depth. The last grouping of information is for data fields ext racted from the “Basin_Factors” tab, such as: hours of operation, molecular weight of the gas; an d fraction of benzene in the VOC emissions.

The traditional nonpoint sources inventory contains activity data, emission factor, control information, and then emissions. Thus, after the la st grouping of extracted information: 1) the activity data are populated or calculated; 3) the e mission factor data are populated or calculated; and 3) the emissions are calculated. I n each of the worksheets, the User has the ability to adjust emissions to avoid including poin t source emissions in the area source emissions total, and then a final nonpoint emission estimate is generated. Each workbook has a crosswalk of point sources to nonpoint sources SCCs which may be useful in entering the point source emissions adjustment.

There is also enhanced flexibility in adjusting inp uts at the county- or basin-level, as well as color shading to assist the user with interpretatio n of data. The color shadings are as follows:

x Yellow: the user can overwrite the data in these ce lls;

x Red: point source activity adjustments can be made by the user. This is not recommended unless the adjustments cover all upstream oil and g as emissions that are currently included in the state’s point sources emissions inventory; a nd

x Orange: point source emission adjustments can be ma de by the User in each SCC

worksheet.December 2012



### 44



## 6.2 Summary of methodologies used to estimate emissi ons for each source

category

Emissions for individual oil and gas area source ca tegories are developed following a bottom-up approach that begins with developing mass emission rates for each pollutant based on an activity surrogate (e.g. tons per well, tons per ba rrel of oil, tons per feet drilled). These bysurrogate emission rates are then scaled to county- level emissions by multiplying the emission rates by the scaling surrogate or activity from a p articular county (e.g. gas well counts, horizontal feet drilled, crude oil production, etc. ). Basin-level emissions are calculated as the sum of emissions from each county within the basin geographical limits.

Emissions calculations are performed within the Emi ssions Calculator Tool; data field names for calculation inputs are shown in a table at the end of each source category section in the same format and nomenclature as they would appear in the tool. Basin-specific input data for each source category calculation are located in the ‘BAS IN_FACTORS’ and ‘INPUTS_ACTIVITY’ tabs of the tool which include emissions factors and equipm ent/activity factors for the various source categories. County-level production statistics, als o referred to here as scaling surrogates (e.g. well counts, gas production, oil production, etc.), and other activity factors such as the fraction of gas wells with wellhead compressors are also loc ated in the ‘INPUTS_ACTIVITY’ tab. Other input data referenced here may also be found in the ‘EMISSION_FACTORS’ tab, which contains average emission rates that were derived from the l iterature and are U.S. national default values (not regionally specific). Values in this ta b are standard emissions rates generally defined by equipment properties or process characteristics, such as those for engine emissions, flaring emissions and by-component fugitives that do not ty pically vary by region . Therefore, venting emission rates, which are highly dependent on regio nal gas compositions, are not included in this tab but are instead included in the ‘BASIN_FAC TORS’ tab.

The following sections describe emissions calculati ons for each source category; it is noted that some of these methodologies may apply to multiple S CCs and thus, are calculated separately in the individual sheets per SCC within the tool. The corresponding tab (calculation sheet) where each methodology is applied is included for referen ce.

6.2.1 Artificial Lifts

Calculation sheet: ARTIFICIAL_LIFTS_2310000330

Artificial lifts in this analysis refer specificall y to engines located at oil wells that provide lift to the liquids in a well up to the wellhead. Generally , artificial lift engines such as pump jacks are small natural-gas fired engines similar to wellhead compressors. In the past decade there has

been an increased use of electrified artificial lif t engines powered by the grid; for this kind,

emissions are assumed to be zero. The basic methodo logy for estimating emissions from a single non-electrified artificial lift engine is sh own below:December 2012



### 45

Equation 1) 185

, 907 annual i engine 

### t

LF HP EF E u

u u

where:

E engine 

### are emissions from an artificial lift engine [ton/ year/engine]

EF i 

### is the emissions factor of pollutant i [g/hp-hr]

HP is the horsepower of the engine [hp]

LF is the load factor of the engine

t annual 

### is the annual number of hours the engine is used [ hr/yr 907,185 is the unit conversion factor g/ton

Extrapolation to county-level emissions

It is recommended that artificial lift engine emiss ions be scaled up to the county level on the basis of oil well counts. The methodology for scal ing up artificial lift engine emissions is shown

below:

Equation 2) TOTAL pumpjack engine TOTAL engine 

### W CF f E n E u

 u u u )

1(

,



### where:

E engine,TOTAL 

### is the total emissions from artificial lift engine s in a county [ton/yr]

E engine 

### is the total emissions from an artificial lift eng ine (as shown in Equation 1) [ton/yr/engine]

n is the total number of artificial lift engines per well, generally equal to 1 (n=1) [engine/well]

W TOTAL 

### is the total number of oil wells in a county [wells] f pumpjack 

### is the fraction of oil wells with artificial lift engines

CF is the fraction of artificial lift engines that ar e electrified

Source category data fields within the tool

FIELD FIELD DESCRIPTION Units WORKSHEET TAB
FRACTION_ARTIFICIAL_ELECTRIC Fraction of artificial lift engines that

are electric Unitless BASIN_FACTORS

ARTIFICIAL_ENGINE_HP Typical horsepower (HP) of an artificial lift engine HP BASIN_FACTORS

ARTIFICIAL_LOAD_FACTOR_LIFT_ENGINES Typical load fa ctor of an artificial lift
engine Unitless BASIN_FACTORS

ARTIFICIAL_ANNUAL_ACTIVITY_HOURS Typical number of hours operated for artificial lift engines Hours

per year BASIN_FACTORS

EMISSION_FACTOR_NUMERATOR Engine emissions factor for pollutant i g/hp-hr EMISSION_FACTORS

FRACT_OILWELLS_NEED_COMPRESSION Fraction of oil well s with artificial lift engines Unitless INPUTS_ACTIVITYDecember 2012



### 46

6.2.2 Wellhead Compressor Engines

Calculation sheet(s): WELLHEAD_COMPRESSORS_23100212 02; WELLHEAD_COMPRESSORS_2310021302

Wellhead compressor engines are generally small nat ural-gas fired engines located at the well site and used to boost produced gas pressure from d ownhole pressure to the required pressure for delivery to a transmissions pipeline. The fract ional usage of these engines will depend on the basin characteristics; hence for those basins t hat largely require wellhead compression, this may be a significant area source of NOx emissions. Compressor engines found at a wellhead were categorized into two main categories in this a nalysis and thus emissions are estimated for each type of engine and consequently extrapolated t o county-wide emissions. These categories of compressors are:

x Rich burn compressors

x Lean burn compressors

The basic methodology for estimating emissions from wellhead compressor engines is shown in
Equation 3:

Equation 3) ) 1( 185

, 907 , i controlled annual i
type engine 

### CF F t LF HP EF E u

 u u u u



### where:

E engine 

### are emissions from a particular type (rich vs. lea n) of compressor engine [ton/year/engine]

EF i 

### is the emissions factor of pollutant i [g/hp-hr] (note that this may be different for NOx emissions from rich-burn vs. lean-burn engines)

HP is the horsepower of the engine [hp]

LF is the load factor of the engine

t annual 

### is the annual number of hours the engine is used [ hr/yr]

F controlled 

### is the fraction of compressors of a particular type (rich vs. lean) that are controlled

CF i 

### is the control factor for controlled engines for p ollutant i 907,185 is the unit conversion factor g/ton

Extrapolation to county-level emissions

County-level emissions are made up of the combinati on of emissions from each type of wellhead compressor, rich burn and lean burn. Emis sions are scaled to county level using the usage fraction (C) of each engine type against all other compressor engines, the fraction of wells with wellhead compressor engines, and the tot al gas well count in a county, according to equation below:December 2012



### 47

Equation 4) wellhead TOTAL lean engine lean rich engine rich TOTAL engine 

### f W E C E C E u u 

, , ,



### where:

E engine,TOTAL 

### is the total emissions from compressor engines in a county [ton/yr]

E engine,lean 

### is the total emissions from a single lean burn com pressor engine per Equation (3) [ton/yr]

E engine,rich 

### is the total emissions from a single rich burn com pressor engine per Equation (3) [ton/yr]

C lean 

### is the fraction of lean-burn wellhead compressors in the basin amongst all wellhead

compressors
C rich 

### is the fraction of rich-burn wellhead compressors in the basin amongst all wellhead

compressors
W TOTAL 

### is the total gas well count in a county f wellhead 

### is the fraction of all gas wells in the basin with wellhead compressor engines

Source category data fields within the tool

FIELD FIELD DESCRIPTION Units WORKSHEET TAB
EMISSION_FACTOR_NUMERATOR Engine emissions factor for
pollutant i g/hp-hr EMISSION_FACTORS

FRACTION_RICH_BURN Fraction of wellhead compressor
engines that are rich-burn Unitless BASIN_FACTORS

FRACTION_LEAN_BURN Fraction of wellhead compressor
engines that are lean-burn Unitless BASIN_FACTORS

LEAN_BURN_LOAD_FACTOR Typical load factor of a lean -burn
wellhead compressor engine Unitless BASIN_FACTORS

RICH_BURN_LOAD_FACTOR Typical load factor of a rich -burn
wellhead compressor engine Unitless BASIN_FACTORS

LEAN_BURN_CONTROLLED Fraction of wellhead lean-burn
compressor engines that are

controlled Unitless BASIN_FACTORS

RICH_BURN_CONTROLLED Fraction of wellhead rich-burn
compressor engines that are

controlled Unitless BASIN_FACTORS

LEAN_BURN_HP Typical horsepower (HP) of a leanburn wellhead compressor engine HP BASIN_FACTORS

RICH_BURN_HP Typical horsepower (HP) of a richburn wellhead compressor engine HP BASIN_FACTORS

ANNUAL_ACTIVITY_HR Typical number of hours operated
for wellhead compressor engines Hours per

year BASIN_FACTORS

FRACT_GASWELLS_NEED_COMPRESSION Fraction of gas well s needing
wellhead compression, HPDI
Database or Survey Data Unitless INPUTS_ACTIVITYDecember 2012



### 48

6.2.3 Lateral/Gathering Compressor Engines

Calculation sheet(s): LATERAL_COMPRESSORS_231002135 1; LATERAL_COMPRESSORS_2310021251

Lateral compressor engines are used to gather gas f rom multiple individual wells, generally serving groups of approximately 10 to 100 wells. Th ese engines are generally medium size and larger than wellhead compressor engines, but often not large enough to trigger Title V or other major source permitting requirements. Lateral compr essor engines were categorized into two main categories and thus emissions are estimated fo r each type of engine and consequently extrapolated to county-wide emissions. These catego ries of compressors are:

x Rich burn compressors

x Lean burn compressors

The basic methodology for estimating emissions from lateral compressor engines is shown in
Equation 5:

Equation 5) ) 1( 185

, 907 , i controlled annual i
type engine 

### CF F t LF HP EF E u

 u u u u



### where:

E engine,type 

### are emissions from a particular type (rich vs. lea n) of compressor engine [ton/year/engine]

EF i 

### is the emissions factor of pollutant i [g/hp-hr] (note that this value may be differ between rich-burn vs. lean-burn engines)

HP is the horsepower of the engine [hp]

LF is the load factor of the engine

t annual 

### is the annual number of hours the engine is used [ hr/yr]

F controlled 

### is the fraction of lateral compressors of a particu lar type that are controlled

CF i 

### is the control factor for controlled engines for p ollutant i 907,185 is the unit conversion factor g/ton

Extrapolation to county-level emissions

County-level emissions are represented by a mix of the two types of lateral compressors. Single engine emissions are scaled to county level using t he fraction (C) of these engine types to total engines, the fraction of wells served by lateral co mpressor engines, and the total gas well count in a county, according to equation below:

Equation 6)

lateral TOTAL lean engine lean rich engine rich TOTAL engine 

### N W E C E C E 1

, , , 

### u u December 2012



### 49

where:

E engine,TOTAL 

### is the total emissions from compressor engines in a county [ton/yr]

E engine,lean 

### is the total emissions from a single lean burn com pressor engine per Equation (5) [ton/yr]

E engine,rich 

### is the total emissions from a single rich burn com pressor engine per Equation (5) [ton/yr]

C lean 

### is the fraction of lean-burn lateral compressors i n the basin amongst all lateral

compressors
C rich 

### is the fraction of rich-burn lateral compressors i n the basin amongst all lateral

compressors
W TOTAL 

### is the total gas well count in a county

N lateral 

### is the number of gas wells served by a lateral com pressor engine

Source category data fields within the tool

FIELD FIELD DESCRIPTION Units WORKSHEET TAB

EMISSION_FACTOR_NUMERATOR Engine emissions factor for pollutant i g/hp-hr EMISSION_FACTORS

LATERAL_HRS_OPERATION Typical number of hours opera ted for
lateral/gathering compressor engines Hours per year BASIN_FACTORS

LATERAL_NUM_WELLS_PER_LINE No. wells served by sing le lateral

compressor Wells per

compressor BASIN_FACTORS

LATERAL_FRACT_RICH Fraction of lateral compressors that

are rich-burn Unitless BASIN_FACTORS

LATERAL_FRACT_LEAN Fraction of lateral compressors that

are lean-burn Unitless BASIN_FACTORS

LATERAL_LEAN_HP Typical horsepower (HP) of a leanburn lateral compressor engine HP BASIN_FACTORS

LATERAL_RICH_HP Typical horsepower (HP) of a richburn lateral compressor engine HP BASIN_FACTORS

LATERAL_LEAN_LOAD_FACT Typical load factor of a lea n-burn
lateral compressor engine Unitless BASIN_FACTORS

LATERAL_RICH_LOAD_FACT Typical load factor of a ric h-burn
lateral compressor engine Unitless BASIN_FACTORS

LATERAL_LEAN_ENGINE_CONT_FRAC Fraction of lean-burn lateral
compressor engines that are

controlled Unitless BASIN_FACTORS

LATERAL_RICH_ENGINE_CONT_FRAC Fraction of rich-burn lateral
compressor engines that are

controlled Unitless BASIN_FACTORSDecember 2012



### 50

6.2.4 Condensate tanks

Calculation sheet: CONDENSATE_TANKS_2310021010

Condensate storage tanks are considered a significa nt source of VOC emissions. Tank losses are generated by flashing and by working and breathing processes, although generally the emissions are dominated by flashing losses. This an alysis uses a combined-losses emissions factor and assumes that the gas compositions from b oth processes are identical. The methodology for estimating condensate tank combined losses is shown below:

Equation 7) 

# > @

efficiency captured VOC tanks condensate

VOC ks condensate 

## C C F EF E u u

 u 1 2000 , ,

, tan

,



### where:

E condensate,tanks,VOC



### is the VOC emissions per liquid unit throughput fr om condensate tanks [tons/bbl]

EF condensate,tanks,VOC



### is the VOC emissions factor for combined losses fr om condensate tanks [lb-VOC/bbl]

C capture 

### is the capture efficiency of the flare

C efficiency 

### is the control efficiency of the flare

F is the fraction of condensate tanks with flares 2000 is the unit conversion factor lb/ton

The methodology for estimating condensate tank comb ined losses from other pollutants i in the
flashing gas is shown below:

Equation 8) ܧ ௡௢௖ௗ௘௡௦௔௧௘

, ௧௔௡௞௦

, ௜ 

### = ܧ ௡௢௖ௗ௘௡௦௔௧௘

, ௧௔௡௞௦

, ௏ை஼ 

### × ௪௘௜௚௛௧ ௙௥௔௖௧௜௢௡ ೔ ௪௘௜௚௛௧ ௙௥௔௖௧௜௢௡ ೇೀ಴



### where:

E condensate,tanks,i



### is the emissions of pollutant i per liquid unit t hroughput from condensate tanks [tons/bbl]

E condensate,tanks,VOC



### is the VOC emissions per liquid unit throughput fr om condensate tanks [tons-VOC/bbl] weight fraction is the mass-based concentration of pollutant i and VOC in the flashing gas

Flaring emissions from condensate tank controls

This source category includes any flaring emissions associated with controls applied to
condensate tanks. The methodology for estimating em issions from flaring of condensate tank
flash gas is described below:December 2012



### 51

Equation 9)



### 2000 1000 , , , 

###  ̧ 1 ·  ̈ © § u
u u u u u HV EF C C F Q P E i efficiency captured tanks condensate county i tank flare



### where:

E flare,tank,i 

### is the county-wide flaring emissions of pollutant i from condensate tank controls [ton/yr]

Q condensate,tank 

### is the uncontrolled volume of tank losses vented pe r unit of condensate throughput [MCF/bbl]

C capture 

### is the capture efficiency of the flare

C efficiency 

### is the control efficiency of the flare

F is the fraction of condensate tanks with flares

EF i 

### is the flaring emissions factor for pollutant i [lb/MMBtu]

HV is the local heating value of the gas [BTU/SCF]

P county 

### is the annual throughput of condensate production i n the county [bbl/yr] 2000 is the unit conversion factor lb/ton 1000 is the unit conversion factor MCF/MMCF

The methodology for estimating SO 2 

### emissions from flaring of oil and condensate flash gas is

shown below:

Equation 10)



### 907185 2

10 5.3 2 2 5 ,

, , 

### u u  ̧  ̧  ̧  ̧

1 ·

 ̈  ̈  ̈  ̈

© §

u u u  ̧ 1 ·  ̈ © § u

u u u u

 S H

gas county efficiency captured tank condensate

SO tank flare 

### f

T MW R P

C C F Q P E

where:

2

, , SO tank flare 

### E 

### is the county-wide SO 2 

### flaring emissions from condensate tanks controls
[ton/yr]

P is atmospheric pressure [1 atm]

R is the universal gas constant [0.082 L-atm/mol-K]

MW gas 

### is the molecular weight of the flash gas [g/mol]

T is the atmospheric temperature [298 K]

S H 

### f

2 

### is the mass fraction of H 2 

### S in the flash gas

Q condensate,tank, 

### is the uncontrolled volume of tank losses vented pe r unit of condensate throughput [MCF/bbl]

C capture 

### is the capture efficiency of the flare

C efficiency 

### is the control efficiency of the flare

F is the fraction of condensate tanks with flaresDecember 2012



### 52

P county 

### is the annual throughput of condensate production c ounty-wide [bbl/yr]

3.5x10 -5 

### is the unit conversion factor MCF/L 907185 is the unit conversion factor g/ton

Extrapolation to county-level emissions

To estimate county-wide total condensate tank emiss ions, which includes venting and flaring, for each pollutant i, Equation 11 below is used:

Equation 11) i k flare i ks condensate TOTAL ks cond 

## E P E E

, tan

, , tan

, , tan

. 

##  u

where

E cond.tanks,TOTAL 

### is the county-wide total emissions for pollutant i from condensate tanks [tons/yr]

E condensate,tanks,i



### is the combined losses of pollutant i per liquid u nit throughput from condensate tanks [tons/bbl]

P is the annual production of condensate county-wide [bbl/yr]

E flare,tank,i 

### is the county-wide flaring emissions of pollutant i from condensate tank controls [ton/yr]

Source category data fields within the tool

FIELD FIELD DESCRIPTION Units WORKSHEET TAB
COND_TANK_FRAC_TO_TANKS Fraction of condensate dire cted to

tanks Unitless BASIN_FACTORS

COND_TANK_FLARE_FRAC Fraction of condensate tanks w ith

a flare Unitless BASIN_FACTORS

COND_TANK_FLASH_GAS_VOC_FRAC VOC fraction of the fl ash gas Unitless BASIN_FACTORS

COND_TANK_FLARE_CAPT_EFF Capture Efficiency of the flare Unitless BASIN_FACTORS

COND_TANK_FLARE_CONT_EFF Control Efficiency of the flare Unitless BASIN_FACTORS

COND_TANK_AVG_FLASH_LOSSES Flashing emission facto r VOC lost
per barrel (BBL) of condensate
throughput LB VOCS/BBL BASIN_FACTORS

COND_TANK_AVG_WORK_BREATH_LOSS Working/Breathing emission
factor VOC lost per barrel (BBL) of
condensate throughput LB VOCS/BBL BASIN_FACTORS

COND_TANKS_NUM_PER_WELL Number of condensate tanks per

well COUNT BASIN_FACTORS

COND_TANK_VOC_LOSS_THROUGHPUT Emission factor of VO C per barrel
(BBL) of condensate throughput LB VOC/BBL BASIN_FACTORS

COND_TANK_FLASH_GAS_VENTING_RAT

E Volume of flash gas vented per
BBL of condensate throughput MCF/BBL BASIN_FACTORS

COND_TANK_LOCAL_HV Heating value of the flared gas at

the condensate tank BTU/SCF BASIN_FACTORSDecember 2012



### 53

FIELD FIELD DESCRIPTION Units WORKSHEET TAB
COND_TANK_FRACT_H2S Fraction of hydrogen sulfide in the
flared gas at the condensate tank Unitless BASIN_FACTORS

COND_TANK_MW_GAS Molecular weight of the flash gas
being flared at the condensate

tank G/MOL BASIN_FACTORS

COND_TANK_FACTOR_CH4_VOC Methane ratio to VOC being
emitted from condensate storage

tanks Unitless BASIN_FACTORS

COND_TANK_FACTOR_BENZ_VOC Benzene fraction of VOC b eing
emitted from condensate storage

tanks Unitless BASIN_FACTORS

COND_TANK_FACTOR_ETHYLBENZ_VOC Ethylbenzene fraction of VOC
being emitted from condensate
storage tanks Unitless BASIN_FACTORS

COND_TANK_FACTOR_TOLUENE_VOC Toluene fraction of VO C being
emitted from condensate storage

tanks Unitless BASIN_FACTORS

COND_TANK_FACTOR_XYLENE_VOC Xylene fraction of VOC being
emitted from condensate storage

tanks Unitless BASIN_FACTORS



### 6.2.5 Dehydrators

Calculation sheet: DEHYDRATORS_2310021400

In the current analysis, this source category refer s to wellhead dehydrator units. Dehydrator units are used to remove excess water from produced natural gas prior to delivery to the pipeline or to a gas processing plant. Two main sou rces of emissions are found in a dehydrator device: hydrocarbon emissions (including VOC, HAPs, CH 4 

### ) are generated in the dehydrator still vent, and combustion emissions are generated in the dehydrator reboiler. In addition, if dehydrator still vents are controlled by flare, com bustion emissions from flaring controls contribute to the total dehydrator emissions. The b asic methodology for estimating countywide emissions from dehydrator still vents is shown in Equation 12:

Equation 12) 

# > @

efficiency captured stillvent
VOC stillvent 

### C C F EF P E u u

 u

u u 1 2000 1000 ,



### where:

E stillvent,VOC 

### is the county-wide VOC emissions from dehydrator st ill vents [ton/yr]

EF stillvent 

### is the VOC emission factor for dehydrator still ven t per unit of gas throughput [lbVOC/MMSCF]

P is the annual county-wide throughput of gas (gas pr oduction) [MCF/yr]

F is the fraction of dehydrator vents with flaresDecember 2012



### 54

C capture 

### is the capture efficiency of the flare

C efficiency 

### is the control efficiency of the flare 2000 is the unit conversion factor lb/ton 1000 is the unit conversion factor MCF/MMCF

The methodology for estimating dehydrator still ven t emissions from other pollutants i is shown

below

Equation 13) ܧ ௦௧௜௟௟௩௘௡௧

, ௜ 

### = ܧ

௦௧௜௟௟௩௘௡௧

, ௏ை஼ 

### × ௪௘௜௚௛௧ ௙௥௔௖௧௜௢௡ ೔

௪௘௜௚௛௧ ௙௥௔௖௧௜௢௡ ೇೀ಴



### where:

E stillvent,i 

### is the county-wide emissions of pollutant i from de hydrator still vents [ton/yr]

E stillvent,VOC 

### is the county-wide VOC emissions from dehydrator st ill vents [ton/yr] weight fraction is the mass-based concentration of pollutant i or VOC in the vented gas

The basic methodology for estimating emissions for the dehydrator reboiler is equivalent to

that of a standard field heater:

(14 Equation ܧ ௥௘௟௜௢௕௘௥

, ௜ 

### = ܰ × ாி ೔ × ொ ೝ೐್೚೔೗೐ೝ × ௧ ೌ೙೙ೠೌ೗ × ௛௖

ு௏ ೗೚೎ೌ೗ × ଵ

. ଵ଴ ల × ଶ଴଴଴ 

### × ܹ

where:

E reboiler,i 

### is the county-wide emissions from pollutant i from dehydrator reboilers [ton/yr]

EF i 

### is the emission factor for pollutant i for natural gas-fired small boilers [lb/MMSCF]

Q reboiler 

### is the heater size [Btu/hr]

HV local 

### is the local natural gas heating value [Btu local 

### /SCF]

t annual 

### is the annual hours of operation [hr]

hc is a heater cycling fraction of operating hours th at the heater is firing

N is the number of dehydrators per well [1/well]

W is the county-wide number of active gas wells in a particular year [well/yr] 2000 is the unit conversion factor lb/ton

1.10 6 

### is the unit conversion factor SCF/MMSCF

Flaring emissions from dehydrator venting controls

The methodology for estimating county-wide emission s from flaring of dehydrator still vent gas

is described below

Equation 15)



### 2000 10 6 , , , 

###  ̧ 1 ·  ̈ © § u
u u u u u HV EF C C F Q G E i efficiency captured vent dehydrator i dehy flareDecember 2012



### 55

where:

E flare,dehy 

### is the county-wide emissions of pollutant i from d ehydrator vent gas flaring [ton/yr]

Q dehydrator,vent 

### is the volume of gas flared per unit of gas through put in dehydrator [MCF vented/MMSCF natural gas]

C capture 

### is the capture efficiency of the flare

C efficiency 

### is the control efficiency of the flare

F is the fraction of dehydrators with flares

EF i 

### is the flaring emissions factor for pollutant i [lb/MMBtu]

HV is the local heating value of the gas [BTU/SCF]

G is the county-wide gas production [MMSCF/yr] 2000 is the unit conversion factor lb/ton

1.10 6 

### is the unit conversion factor SCF/MMSCF

The methodology for estimating SO 2 

### emissions from flaring of dehydrator vent gas is s hown

below

Equation 16)



### 907185 2

10 5.3 2 2 5 ,

, , 

### u u  ̧  ̧  ̧  ̧

1 ·

 ̈  ̈  ̈  ̈

© §

u

u u  ̧ 1 ·  ̈ © § u

u u u

u

 S H

gas efficiency

captured vent dehydrator

SO dehydrator flare 

### f

T MW R C

C F Q G P E

where:

2 , , SO dehydrator flare 

### E 

### is the county-wide SO 2 

### flaring emissions from flaring of dehydrator vent gas [ton/yr]

P is atmospheric pressure [1 atm]

Q dehydrator,vent 

### is the volume of gas flared per unit of gas through put [MCF vented/MMSCF natural gas]

C capture 

### is the capture efficiency of the flare

C efficiency 

### is the control efficiency of the flare

F is the fraction of dehydrators with flares

R is the universal gas constant [0.082 L-atm/mol-K]

MW gas 

### is the molecular weight of the dehydrator venting gas [g/mol]

T is the atmospheric temperature [298 K]

S H 

### f

2 

### is the mass fraction of H 2 

### S in the dehydrator venting gas

G is the county-wide gas production [MMSCF/yr]

3.5x10 -5 

### is the unit conversion factor MCF/L 907185 is the unit conversion factor g/tonDecember 2012



### 56

Extrapolation to county-level emissions

Equations 12-16 provide direct county-level estimat es of pollutant emissions from dehydrator still vents, reboilers, and flaring controls. Emis sions of the same pollutant each of these three sub-categories should be added together to arrive a t total county-level dehydrator emissions (still vent + reboiler + flaring).

Source category data fields within the tool

FIELD FIELD DESCRIPTION Units WORKSHEET TAB
DEHYD_FRACT_FLARES Fraction of dehydrators with fla res Unitless BASIN_FACTORS

DEHYD_STILL_VENT_VOC_EF VOC Stillvent emission factor LB
VOC/MMSCF BASIN_FACTORS

DEHYD_REBOILER_RATING Heater size rating BTU/HR BAS IN_FACTORS

DEHYD_LHV Heating value of the natural gas

used for fuel BTU/SCF BASIN_FACTORS

DEHYD_OP_HRS Typical number of hours operated

for the reboiler Hours per year BASIN_FACTORS

DEHYD_HEATING_CYCLE Fraction to account for the
fraction of operating hours that
the heater is firing Unitless BASIN_FACTORS

DEHYD_NUM_PER_WELL Number of dehydrators per well C OUNT/WELL BASIN_FACTORS

DEHYD_VOL_GAS_FLARED_THROUGHPUT Volume of gas flare d per unit of
natural gas throughput MCF/MMSCF BASIN_FACTORS

DEHYD_VOC_FRACT_FLARE_GAS VOC fraction in the Flare d Gas Unitless BASIN_FACTORS

DEHYD_H2S_FRACT_FLARE_GAS Hydrogen sulfide fraction in the

Flared Gas Unitless BASIN_FACTORS

DEHYD_MW Molecular weight of the flared gas G/MOL BASI N_FACTORS

DEHYD_FLARING_CAPTURE_EFF Capture Efficiency of the flare Unitless BASIN_FACTORS

DEHYD_FLARING_CONTROL_EFF Control Efficiency of the flare Unitless BASIN_FACTORS

DEHYD_STILL_VENT_CH4_VOC Methane ratio to VOC being
emitted from dehydrator still vent Unitless BASIN_FACTORS

DEHYD_STILL_VENT_BENZ_VOC Benzene ratio to VOC being
emitted from dehydrator still vent Unitless BASIN_FACTORS

DEHYD_STILL_VENT_ETHYLBENZ_VOC Ethylbenzene ratio t o VOC being
emitted from dehydrator still vent Unitless BASIN_FACTORS

DEHYD_STILL_VENT_TOLEUNE_VOC Toluene ratio to VOC b eing
emitted from dehydrator still vent Unitless BASIN_FACTORS

DEHYD_STILL_VENT_XYLENE_VOC Xylene ratio to VOC bei ng emitted
from dehydrator still vent Unitless BASIN_FACTORSDecember 2012



### 57

6.2.6 Drilling Rigs

Calculation sheet: DRILL_RIGS_2310000220

Drilling rig emissions considered three primary eng ines: Draw works, Mud pumps and Generators. Each of these three engine types is u sed for differing periods of time throughout the drilling process and are likely to have differe nt load factor and sizes. Each of the three engines is also likely to be of differing model yea rs and hence Tier levels. Some drilling rigs operate with a set of large generator engines which provides electric power to the other prime movers of the rig – draw works and mud pumps; these type of rigs are referred to here as diesel-electric rigs. In order to account for vari ations in engine characteristics and their effect i n final emissions, average emissions for each type of engine k (k=drawworks, mum pumps or generators) is estimated separately. In addition, o peration parameters such as time and load factor vary for vertical wellbores and horizontal w ellbores; hence emissions were estimated separately for both drilling methods using equation 17 and 18.

Emissions for a single engine of type k are estimat ed according to Equation 17:

(17 Equation ܧ ௘௡௜௚௡௘ ௞

, ௜ 

### = ாி ೔ × ு௉ ೖ × ௅ி ೖ × ௧ ೐ೡ೐೙೟ × ௡

ଽ଴଻

, ଵ଼ହ



### where:

E engine k,i 

### are emissions of pollutant i from an engine type k [ton/spud]

EF i 

### is the average emissions factor of pollutant i [g/hp-hr]

HP k 

### is the average horsepower for an engine k in the b asin [hp]

LF k 

### is the average load factor of the engine k

t event 

### is the number of hours engine k is used [hr/spud]
907,185 is the mass unit conversion [g/ton]

n is the number of type-k engines in the typical dril l rig

The emission factor for pollutant i, EF i 

### , is an average emissions factor derived from EPA’s NONROAD2008 model and based on the representative p opulation of drilling engine of various

tier levels in NONROAD. The emissions factor for dr ill-rig equipment varies by horsepower range, and there are three possible horsepower bins applicable to the typical range of equipment sizes for drill rig engines. Hence, three sets of possible engine emissions factors (by HP) are used.

Emissions from a single drill rig ൫ܧ ௗ௥௜௟௟௥௜௚்ை்஺௅

, ௜ 

### ൯ are estimated in Equation 18 as the sum of
individual emissions from each drill rig engine as calculated with Equation 17 in [tons/spud]:

Equation 18) ܧ ௗ௥௜௟௟௥௜௚்ை்஺௅

, ௜ 

### = σ ܧ ௘௡௜௚௡௘ ௞

, ௜



### Two distinct drill-rigs configurations may be found in various basins:

x Diesel-mechanical (D) drill rigs: in which all k engines are diesel-fueledDecember 2012



### 58

x Diesel-electric (DE) powered drill rigs: in which o nly the generator is powered by diesel and the draw works and mud pumps are electric (and thus do not have direct emissions associated with them)

Thus equations 17 and 18 will vary by these two con figurations, and a set of input values for each the four combinations of vertical/horizontal w ellbores and diesel/diesel-electric rigs must be applied.

Emissions from drill rigs correlate to the depth of the wellbore, which will vary between horizontal and vertical wellbores; thus emissions c an be estimated on a “per foot drilled’ basis using the equation below

Equation 19) ܧൣ ௚௡௜௟௟௜௥ௗ

, ௜ 

### ൧

௩௘௥௧௜௖௔௟ / ௛௢௥௜௭௢௡௧௔௟ 

### = ൤ ா ೏ೝ೔೗೗ೝ೔೒೅ೀ೅ಲಽ

, ೔ ವ ×( ଵିி ವಶ ) ାா ೏ೝ೔೗೗ೝ೔೒೅ೀ೅ಲಽ

, ೔ ವಶ × ி ವಶ

஽ ೞ೛ೠ೏ 

### ൨

ೡ೐ೝ೟೔೎ೌ೗

೓೚ೝ೔೥೚೙೟ೌ೗



### where

ܧ ௚௡௜௟௟௜௥ௗ

, ௜ 

### is the total emissions for a horizontal or vertica l spud per unit of feet drilled [tons/ft]

ܧ ௗ௥௜௟௟௥௜௚்ை்஺௅

, ௜ ஽ 

### is the emissions from a single diesel-powered dri ll rig (from Equation 18)
for a vertical or a horizontal spud [tons/spud]

ܧ ௗ௥௜௟௟௥௜௚்ை்஺௅

, ௜ ஽ா 

### is the emissions from a single diesel-electric dr ill rig (from Equation 18)
for a vertical or a horizontal spud [tons/spud]

F DE 

### is the fraction of drill rigs that are diesel-elec tric

D spud 

### is the average depth of a vertical or horizontal s pud [ft/spud]

Extrapolation to county-level emissions

Emissions per feet drilled are scaled to county-lev el drilling emissions according to Equation 20

Equation 20)

ܧ ௗ௥௜௟௟

, ௖௢௨௡௧௬ି௪௜ௗ௘

, ௜ 

### = ൣܧ ௗ௥௜௟௟௜௡௚

, ௜ 

### ൧

௩௘௥௧௜௖௔௟ 

### × ܦ ௩௘௥௧௜௖௔௟ 

### + ൣܧ ௗ௥௜௟௟௜௡௚

, ௜ 

### ൧

௛௢௥௜௭௢௡௧௔௟ 

### × ܦ ௜௥௢௛௭௢௡௧௔௟



### where:

E drill ,county-wide,i 

### is the total emissions of pollutant i from county- wide drilling activity [tons/yr]

E drilling,i 

### is the total emissions from drilling a single well [tons/ft]

D vertical 

### is the total depth drilled in the county for verti cal wells in a particular year [ft/r]

D horizontal 

### is the total depth drilled in the county for horizo ntal wells in a particular year [ft/yr]December 2012



### 59

Source category data fields within the tool

FIELD FIELD DESCRIPTION Units WORKSHEET TAB
DRILL_FRACT_DIESEL_ELECTRIC Fraction of drill-rigs that are

diesel-electric Unitless BASIN_FACTORS

DRILL_HORIZ_DEPTH_SPUD Average depth per spud,
horizontal drilling FT/SPUD BASIN_FACTORS

DRILL_HORIZ_SPUD_DURATION Average duration per spud

, horizontal drilling HR BASIN_FACTORS

DRILL_HORIZ_FUEL_CONSUMED Average fuel consumed,
horizontal drilling GALLONS BASIN_FACTORS

DRILL_HORIZ_DRAW_HP Average horsepower for
draworks, horizontal drilling HP BASIN_FACTORS

DRILL_HORIZ_DRAW_LOAD_FACTOR Average load factor fo r draworks,
horizontal drilling Unitless BASIN_FACTORS

DRILL_HORIZ_DRAW_NUM_ENGINES_RIG Average number of engines per
rig for draworks, horizontal
drilling COUNT/RIG BASIN_FACTORS

DRILL_HORIZ_DRAW_HRS_SPUD Average number of engines hours
per spud for draworks, horizontal
drilling HR/SPUD BASIN_FACTORS

DRILL_HORIZ_MUD_PUMPS_HP Average horsepower for mud
pumps, horizontal drilling HP BASIN_FACTORS

DRILL_HORIZ_MUD_PUMPS_LOAD_FACTOR Average load facto r for mud
pumps, horizontal drilling Unitless BASIN_FACTORS

DRILL_HORIZ_MUD_PUMPS_NUM_ENGINES_RIG Average number of engines per
rig for mud pumps, horizontal
drilling COUNT/RIG BASIN_FACTORS

DRILL_HORIZ_MUD_PUMPS_HRS_SPUD Average number of eng ines hours
per spud for mud pumps,
horizontal drilling HR/SPUD BASIN_FACTORS

DRILL_HORIZ_GEN_DIESEL_HP Average horsepower for di esel
rigs, horizontal drilling HP BASIN_FACTORS

DRILL_HORIZ_GEN_DIESEL_LOAD_FACTOR Average load fac tor for diesel
rigs, horizontal drilling Unitless BASIN_FACTORS

DRILL_HORIZ_GEN_DIESEL_NUM_ENGINES_RIG Average numb er of engines per
rig for diesel rigs, horizontal
drilling COUNT/RIG BASIN_FACTORS

DRILL_HORIZ_GEN_DIESEL_HRS_SPUD Average number of e ngines hours
per spud for diesel rigs,
horizontal drilling HR/SPUD BASIN_FACTORS

DRILL_HORIZ_GEN_DIESEL_ELEC_HP Average horsepower f or dieselelectric rigs, horizontal drilling HP BASIN_FACTORS

DRILL_HORIZ_GEN_DIESEL_ELEC_LOAD_FACTOR Average loa d factor for dieselelectric rigs, horizontal drilling Unitless BASIN_FACTORSDecember 2012



### 60

FIELD FIELD DESCRIPTION Units WORKSHEET TAB

DRILL_HORIZ_GEN_DIESEL_ELEC_NUM_ENGINES_RIG Average number of engines per
rig for diesel-electric rigs,
horizontal drilling COUNT/RIG BASIN_FACTORS

DRILL_HORIZ_GEN_DIESEL_ELEC_HRS_SPUD Average number of engines hours
per spud for diesel-electric rigs,
horizontal drilling HR/SPUD BASIN_FACTORS

DRILL_VERT_DEPTH_SPUD Average depth per spud, verti cal
drilling FT/SPUD BASIN_FACTORS

DRILL_VERT_SPUD_DURATION Average duration per spud,
vertical drilling HR BASIN_FACTORS

DRILL_VERT_FUEL_CONSUMED Average fuel consumed, vertical
drilling GALLONS BASIN_FACTORS

DRILL_VERT_DRAW_HP Average horsepower for
draworks, vertical drilling HP BASIN_FACTORS

DRILL_VERT_DRAW_LOAD_FACTOR Average load factor for draworks,
vertical drilling Unitless BASIN_FACTORS

DRILL_VERT_DRAW_NUM_ENGINES_RIG Average number of e ngines per
rig for draworks, vertical drilling COUNT/RIG BASIN_FACTORS

DRILL_VERT_DRAW_HRS_SPUD Average number of engines hours
per spud for draworks, vertical
drilling HR/SPUD BASIN_FACTORS

DRILL_VERT_MUD_PUMPS_HP Average horsepower for mud
pumps, vertical drilling HP BASIN_FACTORS

DRILL_VERT_MUD_PUMPS_LOAD_FACTOR Average load factor for mud
pumps, vertical drilling Unitless BASIN_FACTORS

DRILL_VERT_MUD_PUMPS_NUM_ENGINES_RIG Average number of engines per
rig for mud pumps, vertical
drilling COUNT/RIG BASIN_FACTORS

DRILL_VERT_MUD_PUMPS_HRS_SPUD Average number of engin es hours
per spud for mud pumps, vertical
drilling HR/SPUD BASIN_FACTORS

DRILL_VERT_GEN_DIESEL_HP Average horsepower for die sel
rigs, vertical drilling HP BASIN_FACTORS

DRILL_VERT_GEN_DIESEL_LOAD_FACTOR Average load fact or for diesel
rigs, vertical drilling Unitless BASIN_FACTORS

DRILL_VERT_GEN_DIESEL_NUM_ENGINES_RIG Average numbe r of engines per
rig for diesel rigs, vertical drilling COUNT/RIG BASIN_FACTORS

DRILL_VERT_GEN_DIESEL_HRS_SPUD Average number of engines hours
per spud for diesel rigs, vertical
drilling HR/SPUD BASIN_FACTORS

DRILL_VERT_GEN_DIESEL_ELEC_HP Average horsepower fo r dieselelectric rigs, vertical drilling HP BASIN_FACTORS

DRILL_VERT_GEN_DIESEL_ELEC_LOAD_FACTOR Average load factor for dieselelectric rigs, vertical drilling Unitless BASIN_FACTORSDecember 2012



### 61

FIELD FIELD DESCRIPTION Units WORKSHEET TAB

DRILL_VERT_GEN_DIESEL_ELEC_NUM_ENGINES_RIG Average number of engines per
rig for diesel-electric rigs, vertical
drilling COUNT/RIG BASIN_FACTORS

DRILL_VERT_GEN_DIESEL_ELEC_HRS_SPUD Average number of engines hours
per spud for diesel-electric rigs,
vertical drilling HR/SPUD BASIN_FACTORS



### 6.2.7 Pneumatic Devices

Calculation Sheet: PNEUMATIC_GASWELL_2310021300; PN EUMATIC_OILWELL_2310010300

Pneumatic devices are control devices located at th e well site that are powered pneumatically by high-pressure produced gas. These devices are ty pically under operation throughout the year and they may or may not vent the working fluid during operation, making them a potentially significant source of VOC emissions. Th e counts of pneumatic devices vary between oil and gas wells, thus emissions were estimated se parately for both well types. Emissions from pneumatic devices vary by the bleed rate of the dev ice. Here it is assumed that four configurations can be found in a typical well: high bleed, low bleed, intermittent and no bleed. Emissions for the first three types of device i must be determined. The methodology for estimating the emissions from pneumatic devices for a particular type of well are shown in
Equation 21:

Equation 21) 

###  ̧  ̧ 1 ·  ̈  ̈ © §

u

u u  ̧ 1 ·  ̈ © §

u u  ̧ 1 ·  ̈ © §

u u

 

# ¦

5 , 

### 10 5.3 1000 907185 T MW R P t N V f E

gas i annual

i i j
j pneumatic 

### 

where:

E pneumatic,j 

### is the total emissions of pollutant j from all pneumatic devices for a particular type of well (oil vs. gas) [ton/year/well]

i 

### V  

### is the volumetric bleed rate from device i [SCF/hr/device]

N i 

### is the average number of devices i found in a type of well (oil vs. gas) [devices/wel l]

t annual 

### is the number of hours per year that devices were operati ng [8760 hr/yr]

P is the atmospheric pressure [1 atm]

R is the universal gas constant [0.082 L-atm/mol-K]

MW gas 

### is the molecular weight of the gas [g/mol]

T is the atmospheric temperature [298 K] f j 

### is the mass fraction of pollutant j in the vented gas (produced gas)

3.5x10 -5 

### is the unit conversion factor MCF/L 907185 is the unit conversion factor g/ton 1000 is the unit conversion factor SCF/MCFDecember 2012



### 62

Extrapolation to county-level emissions

County-wide pneumatic device emissions for each wel l type were estimated according to

Equation 22:

Equation 22) well j pneumatic j TOTAL pneumatic 

### N

E E u

, , ,



### where:

E pneumatic,TOTAL,j



### is the total pneumatic device emissions of polluta nt j in the county [ton/yr]

E pneumatic,j 

### is the pneumatic device emissions of pollutant j for a type of well (gas vs. oil) [ton/yr/well]

N well 

### is the total number of active gas (or oil) wells i n the county [wells]

Total emissions from pneumatic devices will be the combination of basin-wide emissions from each well type:

Equation 23) 

# > @ > @

oilwells j TOTAL pneumatic gaswells j TOTAL pneumatic j ics allpneumat 

### E

E E

, , , , , 

### 

Source category data fields within the tool

FIELD FIELD DESCRIPTION Units WORKSHEET TAB
PNEUMATIC_GAS_WELL_NO_BLEED_NUM_DEV Count of "No Ble ed" pneumatic
devices at gas wells COUNT BASIN_FACTORS

PNEUMATIC_GAS_WELL_NO_BLEED_BLEED_RATE Bleed rate of "No Bleed"
pneumatic devices at gas wells SCF/HR/

DEVICE BASIN_FACTORS

PNEUMATIC_GAS_WELL_LOW_BLEED_NUM_DEV Count of "Low Bleed" pneumatic
devices at gas wells COUNT BASIN_FACTORS

PNEUMATIC_GAS_WELL_LOW_BLEED_BLEED_RATE Bleed rate o f "Low Bleed"
pneumatic devices at gas wells SCF/HR/

DEVICE BASIN_FACTORS

PNEUMATIC_GAS_WELL_HIGH_BLEED_NUM_DEV Count of "High Bleed"
pneumatic devices at gas wells COUNT BASIN_FACTORS

PNEUMATIC_GAS_WELL_HIGH_BLEED_BLEED_RATE Bleed rate of "High Bleed"
pneumatic devices at gas wells SCF/HR/

DEVICE BASIN_FACTORS

PNEUMATIC_GAS_WELL_INTERM_BLEED_NUM_DEV Count of "In termittent"
pneumatic devices at gas wells COUNT BASIN_FACTORS

PNEUMATIC_GAS_WELL_INTERM_BLEED_BLEED_RATE Bleed rat e of "Intermittent"
pneumatic devices at gas wells SCF/HR/

DEVICE BASIN_FACTORS

PNEUMATIC_OIL_WELL_NO_BLEED_NUM_DEV Count of "No Ble ed" pneumatic

devices at oil wells COUNT BASIN_FACTORS

PNEUMATIC_OIL_WELL_NO_BLEED_BLEED_RATE Bleed rate of "No Bleed"
pneumatic devices at oil wells SCF/HR/

DEVICE BASIN_FACTORS

PNEUMATIC_OIL_WELL_LOW_BLEED_NUM_DEV Count of "Low B leed" pneumatic

devices at oil wells COUNT BASIN_FACTORSDecember 2012



### 63

FIELD FIELD DESCRIPTION Units WORKSHEET TAB
PNEUMATIC_OIL_WELL_LOW_BLEED_BLEED_RATE Bleed rate o f "Low Bleed"
pneumatic devices at oil wells SCF/HR/

DEVICE BASIN_FACTORS

PNEUMATIC_OIL_WELL_HIGH_BLEED_NUM_DEV Count of "High Bleed"
pneumatic devices at oil wells COUNT BASIN_FACTORS

PNEUMATIC_OIL_WELL_HIGH_BLEED_BLEED_RATE Bleed rate of "High Bleed"
pneumatic devices at oil wells SCF/HR/

DEVICE BASIN_FACTORS

PNEUMATIC_GAS_WELL_INTERM_BLEED_NUM_DEV Count of "In termittent"
pneumatic devices at oil wells COUNT BASIN_FACTORS

PNEUMATIC_OIL_WELL_INTERM_BLEED_BLEED_RATE Bleed rat e of "intermittent"
pneumatic devices at oil wells SCF/HR/

DEVICE BASIN_FACTORS

PNEUMATIC_GASWELL_MW Molecular weight of the vented
gas emitted from pneumatic
devices at gas wells G/MOL BASIN_FACTORS

PNEUMATIC_OILWELL_MW Molecular weight of the vented
gas emitted from pneumatic

devices at oil wells G/MOL BASIN_FACTORS

PNEUMATIC_GASWELL_VOC VOC Fraction of vented gas
being emitted from pneumatic
devices at gas wells Unitless BASIN_FACTORS

PNEUMATIC_GASWELL_H2S H2S Fraction of vented gas bei ng emitted from pneumatic devices
at gas wells Unitless BASIN_FACTORS

PNEUMATIC_GASWELL_CO2 CO2 Fraction of vented gas
being emitted from pneumatic
devices at gas wells Unitless BASIN_FACTORS

PNEUMATIC_GASWELL_CH4 CH4 Fraction of vented gas bei ng emitted from pneumatic devices
at gas wells Unitless BASIN_FACTORS

PNEUMATIC_OILWELL_VOC VOC Fraction of vented gas
being emitted from pneumatic

devices at oil wells Unitless BASIN_FACTORS

PNEUMATIC_OILWELL_H2S H2S Fraction of vented gas bei ng emitted from pneumatic devices

at oil wells Unitless BASIN_FACTORS

PNEUMATIC_OILWELL_CO2 CO2 Fraction of vented gas
being emitted from pneumatic

devices at oil wells Unitless BASIN_FACTORS

PNEUMATIC_OILWELL_CH4 CH4 Fraction of vented gas being
emitted from pneumatic devices

at oil wells Unitless BASIN_FACTORS

PNEUMATIC_ANNUAL_OP_HR Typical number of hours
operated for pneumatic devices Hours per year BASIN_FACTORSDecember 2012



### 64

FIELD FIELD DESCRIPTION Units WORKSHEET TAB
PNEUMATIC_OIL_BENZ_VOC Benzene fraction of VOC being
emitted from pneumatic devices

at oil wells Unitless BASIN_FACTORS

PNEUMATIC_OIL_ETHYLBENZ_VOC Ethylbenzene fraction of VOC
being emitted from pneumatic

devices at oil wells Unitless BASIN_FACTORS

PNEUMATIC_OIL_TOLUENE_VOC Toluene fraction of VOC be ing
emitted from pneumatic devices

at oil wells Unitless BASIN_FACTORS

PNEUMATIC_OIL_XYLENE_VOC Xylene fraction of VOC bein g emitted from pneumatic devices

at oil wells Unitless BASIN_FACTORS

PNEUMATIC_OIL_METHANE_VOC Methane fraction of VOC being
emitted from pneumatic devices

at oil wells Unitless BASIN_FACTORS

PNEUMATIC_OIL_H2S Hydrogen sulfide fraction of VOC
being emitted from pneumatic

devices at oil wells Unitless BASIN_FACTORS

PNEUMATIC_GAS_BENZ_VOC Benzene fraction of VOC being
emitted from pneumatic devices
at gas wells Unitless BASIN_FACTORS

PNEUMATIC_GAS_ETHYLBENZ_VOC Ethylbenzene fraction of VOC
being emitted from pneumatic
devices at gas wells Unitless BASIN_FACTORS

PNEUMATIC_GAS_TOLUENE_VOC Toluene fraction of VOC be ing
emitted from pneumatic devices
at gas wells Unitless BASIN_FACTORS

PNEUMATIC_GAS_XYLENE_VOC Xylene fraction of VOC bein g emitted from pneumatic devices
at gas wells Unitless BASIN_FACTORS

PNEUMATIC_GAS_METHANE_VOC Methane fraction of VOC bein g emitted from pneumatic devices
at gas wells Unitless BASIN_FACTORS

PNEUMATIC_GAS_H2S Hydrogen sulfide fraction of VOC
being emitted from pneumatic
devices at gas wells Unitless BASIN_FACTORS



### 6.2.8 Well Completions

Calculation sheet: WELL_COMPLETIONS_GAS_2310121700;
WELL_COMPLETIONS_OIL_2310111700

This category refers to emissions from well complet ions events, which includes initial completions and recompletions. Data provided in the HPDI database includes a count of annualDecember 2012



### 65

well completions (combines initial and recompletion s), thus county-wide emissions will be a combination of the two. However, well completions c haracteristics will vary by well type; hence emissions were estimated separately for gas well co mpletions and oil well completions. The calculation methodology for estimating emissions fr om a single completion event is shown below in Equation 24:

Equation 24) 

### 907185 10 5.3 5 , i

gas completion

i completion 

### f

T MW R Q P E u  ̧  ̧  ̧  ̧

1 ·

 ̈  ̈  ̈  ̈

© §

u

u u  ̧ 1 ·  ̈ © § u





### where:

E completion,i 

### is the uncontrolled emissions of pollutant i from a single completion event [ton/event]

P is atmospheric pressure [1 atm]

Q completion 

### is the uncontrolled volume of gas generated per co mpletion [MCF/event]

R is the universal gas constant [0.082 L-atm/mol-K]

MW gas 

### is the molecular weight of the gas [g/mol]

T is the atmospheric temperature [298 K] f i 

### is the mass fraction of pollutant i in the completion venting gas

3.5x10 -5 

### is the unit conversion factor MCF/L 907185 is the unit conversion factor g/ton

Flaring emissions from well completion controls

The methodology for estimating flaring emissions fr om completion venting processes is

described below

Equation 25) 

### 2000 1000 , 

###  ̧  ̧ 1 ·  ̈  ̈ © §

u u u u u u

county efficiency captured completion i completion flare 

### S HV C C F Q EF E

where:

E flare,completion 

### is the county-wide flaring emissions of pollutant i for well completions [ton/yr]

EF i 

### is the flaring emissions factor for pollutant i [lb/MMBtu]

Q completion 

### is the uncontrolled volume of gas generated per com pletion [MCF/event]

HV is the local heating value of the gas [BTU/SCF]

S county 

### is the county-wide number of well completion events for a particular year [events/yr]

F is the fraction of well completions with flares

C capture 

### is the capture efficiency of the flare

C efficiency 

### is the control efficiency of the flare 2000 is the unit conversion factor lbs/ton 1000 is the unit conversion factor MCF/MMCFDecember 2012



### 66

The methodology for estimating SO 2 

### emissions from flaring of completion vent gas is s hown

below:

Equation 26)



### 907185 2

10 5.3 2 2 5 , , 

### u u  ̧  ̧  ̧  ̧

1 ·

 ̈  ̈  ̈  ̈

© §

u u u  ̧ 1 ·  ̈ © § u

u u u u

 S H

gas efficiency

captured county completion

SO completion flare 

### f

T MW R C

C F S Q P E

where:

2 , , SO completion flare 

### E 

### is the county-wide SO 2 

### flaring emissions from flaring of completion vent gas [ton/yr]

P is atmospheric pressure [1 atm]

Q completion 

### is the uncontrolled volume of gas generated per com pletion [MCF/event]

S county 

### is the county-wide number of well completion events for a particular year [events/yr]

R is the universal gas constant [0.082 L-atm/mol-K]

MW gas 

### is the molecular weight of the completion venting gas [g/mol]

T is the atmospheric temperature [298 K]

S H 

### f

2 

### is the mass fraction of H 2 

### S in the completion venting gas

F is the fraction of well completions with flares

C capture 

### is the capture efficiency of the flare

C efficiency 

### is the control efficiency of the flare

3.5x10 -5 

### is the unit conversion factor MCF/L 907185 is the unit conversion factor g/ton

Extrapolation to county-level emissions

County-wide emissions are obtained by scaling-up we ll completions by well type with the number of completions events (also by well type) fo r a particular year. This can be done applying Equation 27:

Equation 27)

i completion flare green efficiency captured flare county i completion TOTAL completion 

### E F C C F S E E

, , , , 

### 1 

 u u

 u

where:

E completion,TOTAL 

### are the total emissions county-wide of pollutant i from well completions [tons/year]

E completion,i 

### are the completion emissions from a single complet ion event [tons/event]

F green 

### is the fraction of completions in the basin that w ere controlled by green completion techniques

F flare 

### is the fraction of completions in the basin contro lled by flareDecember 2012



### 67

C capture 

### is the capture efficiency of the flare

C efficiency 

### is the control efficiency of the flare

S county 

### is the county-wide total completions events in a pa rticular year [events/year]

E flare,completion,i



### is the county-wide flaring emissions from flaring of completion vent gas [ton/yr]

Source category data fields within the tool

FIELD FIELD DESCRIPTION Units WORKSHEET

TAB
WELL_COMP_VOL_GAS_VENTED Volume of gas generated per completion MCF/EVENT BASIN_FACTORS

WELL_COMP_FRACT_WITH_FLARING Fraction of well comple tions with flares Unitless BASIN_FACTORS

WELL_COMP_FLARING_CONT_EFF Control Efficiency of the flare Unitless BASIN_FACTORS

WELL_COMP_FLARING_CAPTURE_EFF Capture Efficiency of the flare Unitless BASIN_FACTORS

WELL_COMP_CONT_GREEN Fraction of well completions co ntrolled by
green completion techniques Unitless BASIN_FACTORS

WELL_COMP_OIL_VOC_WT_PCT Fraction of VOC in the vent ed gas during
completion at oil wells Unitless BASIN_FACTORS

WELL_COMP_OIL_H2S_WT_PCT Fraction of Hydrogen sulfid e in the vented
gas during completion at oil wells Unitless BASIN_FACTORS

WELL_COMP_OIL_CO2_WT_PCT Fraction of Carbon dioxide in the vented
gas during completion at oil wells Unitless BASIN_FACTORS

WELL_COMP_OIL_CH4_WT_PCT Fraction of Methane in the v ented gas
during completion at oil wells Unitless BASIN_FACTORS

WELL_COMP_OIL_BENZ_WT_PCT Fraction of Benzene in the vented gas
during completion at oil wells Unitless BASIN_FACTORS

WELL_COMP_OIL_ETHYLBENZ_WT_PCT Fraction of Ethylbenz ene in the vented gas
during completion at oil wells Unitless BASIN_FACTORS

WELL_COMP_OIL_TOLUENE_WT_PCT Fraction of Toluene in the vented gas
during completion at oil wells Unitless BASIN_FACTORS

WELL_COMP_OIL_XYLENE_WT_PCT Fraction of Xylene in th e vented gas during
completion at oil wells Unitless BASIN_FACTORS

WELL_COMP_OIL_LHV Heating value of the vented gas du ring
completion at oil wells BTU/SCF BASIN_FACTORS

WELL_COMP_OIL_MW Molecular weight of the vented gas during
completion at oil wells G/MOL BASIN_FACTORS

WELL_COMP_GAS_VOC_WT_PCT Fraction of VOC in the vent ed gas during
completion at gas wells Unitless BASIN_FACTORS

WELL_COMP_GAS_H2S_WT_PCT Fraction of Hydrogen sulfide in the vented
gas during completion at gas wells Unitless BASIN_FACTORS

WELL_COMP_GAS_CO2_WT_PCT Fraction of Carbon dioxide in the vented
gas during completion at gas wells Unitless BASIN_FACTORS

WELL_COMP_GAS_CH4_WT_PCT Fraction of Methane in the v ented gas
during completion at gas wells Unitless BASIN_FACTORSDecember 2012



### 68

FIELD FIELD DESCRIPTION Units WORKSHEET

TAB
WELL_COMP_GAS_BENZ_WT_PCT Fraction of Benzene in the vented gas
during completion at gas wells Unitless BASIN_FACTORS

WELL_COMP_GAS_ETHYLBENZ_WT_PCT Fraction of Ethylbenz ene in the vented gas
during completion at gas wells Unitless BASIN_FACTORS

WELL_COMP_GAS_TOLUENE_WT_PCT Fraction of Toluene in the vented gas
during completion at gas wells Unitless BASIN_FACTORS

WELL_COMP_GAS_XYLENE_WT_PCT Fraction of Xylene in th e vented gas during
completion at gas wells Unitless BASIN_FACTORS

WELL_COMP_GAS_LHV Heating value of the vented gas during
completion at gas wells BTU/SCF BASIN_FACTORS

WELL_COMP_GAS_MW Molecular weight of the vented gas du ring
completion at gas wells G/MOL BASIN_FACTORS



### 6.2.9 Blowdowns

Calculation sheet: BLOWDOWNS_2310021603

This source category refers to the practice of vent ing gas from gas wells to prevent liquid buildup in the well that could limit production. This pr actice is also commonly referred as “liquids unloading”. Vented gas from blowdowns is a VOC emi ssions source. Emissions from blowdowns are based on the average venting volume p er blowdown and the gas composition of the vented gas. Blowdown emissions may be contro lled by a combustion device such as a flare, or may also be controlled by “smart” plunger lift devices, which decrease liquids build-up and thus reduce the amount of venting volume from t he blowdowns. The calculation methodology for estimating emissions from a single blowdown event is shown below in
Equation 28:

Equation 28) 

### 907185 10 5.3 5 , i

gas vented

i blowdown 

### f

T MW R V P E u  ̧  ̧  ̧  ̧

1 ·

 ̈  ̈  ̈  ̈

© §

u

u u  ̧ 1 ·  ̈ © § u





### where:

E blowdown,i 

### is the emissions of pollutant i from a single blowdown event [ton/event]

P is atmospheric pressure [1 atm]

V vented 

### is the volume of vented gas per blowdown [MCF/even t]

R is the universal gas constant [0.082 L-atm/mol-K]

MW gas 

### is the molecular weight of the gas [g/mol]

T is the atmospheric temperature [298 K] f i 

### is the mass fraction of pollutant i in the vented gas

3.5x10 -5 

### is the unit conversion factor MCF/LDecember 2012



### 69

907185 is the unit conversion factor g/ton

Emissions from flare controls for blowdown vents

In case a region applies flaring controls to blowdo wn vents, the methodology for estimating
flaring emissions is described below:

Equation 29)



### 2000 1000 , 

###  ̧  ̧ 1 ·  ̈  ̈ © §

u u u u u u u

blowdown county efficiency captured vented i

blowdown flare 

### N S HV C C F V EF E

where:

E flare,blowdown 

### is the county-wide flaring emissions of pollutant i for blowdowns [ton/yr]

EF i 

### is the flaring emissions factor for pollutant i [lb/MMBtu]

V vented 

### is the volume of vented gas per blowdown [MCF/even t]

HV is the local heating value of the gas [BTU/SCF]

S county 

### is the county-wide number of active gas wells for a particular year [wells]

N blowdown 

### the average number of annual blowdowns per well in the basin [event/yr-well]

F is the fraction of well blowdowns that are flared

C capture 

### is the capture efficiency of the flare

C efficiency 

### is the control efficiency of the flare 1000 is the unit conversion factor MCF/MMCF 2000 is the unit conversion factor lb/ton

The methodology for estimating SO 2 

### emissions from flaring of blowdown gas is shown be low

Equation 30)



### 907185 2

10 5.3 2 2 5 , , 

### u u  ̧  ̧  ̧  ̧

1 ·

 ̈  ̈  ̈  ̈

© §

u u u  ̧ 1 ·  ̈ © § u

u u u u u

 S H

gas efficiency captured blowdown county vented

SO blowdown flare 

### f

T MW R C

C F N S V P E

where:

2 , , SO blowdown flare 

### E 

### is the county-wide SO 2 

### flaring emissions from flaring of blowdown vent ga s [ton/yr]

P is atmospheric pressure [1 atm]

V vented 

### is the volume of vented gas per blowdown [MCF/even t]

S county 

### is the county-wide number of gas wells [wells]

R is the universal gas constant [0.082 L-atm/mol-K]

MW gas 

### is the molecular weight of the blowdown gas [g/mol ]

T is the atmospheric temperature [298 K]

S H 

### f

2 

### is the mass fraction of H 2 

### S in the blowdown venting gasDecember 2012



### 70

F is the fraction of blowdowns with flares

C capture 

### is the capture efficiency of the flare

C efficiency 

### is the control efficiency of the flare

N blowdown 

### the average number of annual blowdowns per well in the basin [event/yr-well]

3.5x10 -5 

### is the unit conversion factor MCF/L 907185 is the unit conversion factor g/ton

Extrapolation to county-level emissions

The total county-level emissions from all blowdowns are evaluated following Equation 31:

Equation 31) efficiency device control wells blowdown i blowdown TOTAL blowdown 

### C F N N E E u

 u u u

, , , 

### 1

where:

E blowdown,TOTAL 

### are the total county-wide emissions of pollutant i from blowdowns [tons/yr]

E blowdown,i 

### are the blowdown emissions from a single blowdown event [tons/event]

F control,device 

### is the fraction of blowdowns in the basin that wer e controlled

C efficiency 

### is the control efficiency of the control technolog y used (plunger lifts for example)

N blowdown 

### is the average number of annual blowdowns per well in the basin [event/yr-well]

N wells 

### is the total number of active gas wells in the county for a particular year [well]

Source category data fields within the tool

FIELD FIELD DESCRIPTION Units WORKSHEET TAB
BLOWDOWN_AVG_FREQ Average number of annual
blowdowns per well EVENT/YEAR BASIN_FACTORS

BLOWDOWN_VOL_GAS_VENTED Volume of gas generated per

blowdown MCF/EVENT BASIN_FACTORS

BLOWDOWN_FREQ_CONT_METHOD Control Technology freque ntly used Type BASIN_FACTORS

BLOWDOWN_FRACT_CONTROLLED Fraction of blowdowns wit h control

method Unitless BASIN_FACTORS

BLOWDOWN_CONTROL_METHD_EFF Control Efficiency of the method Unitless BASIN_FACTORS

BLOWDOWN_VOC_WT_PCT Fraction of VOC in the vented g as during blowdowns Unitless BASIN_FACTORS

BLOWDOWN_H2S_WT_PCT Fraction of Hydrogen sulfide in the
vented gas during blowdowns Unitless BASIN_FACTORS

BLOWDOWN_CO2_WT_PCT Fraction of Carbon dioxide in t he
vented gas during blowdowns Unitless BASIN_FACTORS

BLOWDOWN_CH4_WT_PCT Fraction of Methane in the vented gas
during blowdowns Unitless BASIN_FACTORS

BLOWDOWN_BENZ_WT_PCT Fraction of Benzene in the ven ted gas
during blowdowns Unitless BASIN_FACTORS

BLOWDOWN_ETHYLBENZ_WT_PCT Fraction of Ethylbenzene in the
vented gas during blowdowns Unitless BASIN_FACTORS

BLOWDOWN_TOLUENE_WT_PCT Fraction of Toluene in the vented gas Unitless BASIN_FACTORSDecember 2012



### 71

FIELD FIELD DESCRIPTION Units WORKSHEET TAB
during blowdowns

BLOWDOWN_XYLENE_WT_PCT Fraction of Xylene in the ve nted gas
during blowdowns Unitless BASIN_FACTORS

BLOWDOWN_VENT_MW Molecular weight of the vented gas
during blowdowns G/MOL BASIN_FACTORS



### 6.2.10 Hydraulic Fracturing Pumps

Calculation Sheet: HYDRAULIC_FRACTURING_2310000660

This category refers to equipment used in hydraulic fracturing practices during well completions and recompletions, generally related to unconventio nal oil and gas production such as shale gas and tight sands oil/gas. Engines used during hydrau lic fracturing are generally large dieselfueled pumps that can be a significant NOx emission s source. Average emissions factors for hydraulic fracturing engines were derived from EPA’ s NONROAD2008 model based on the oil equipment source category bin in NONROAD. The basic methodology for estimating exhaust emissions from engines used at a hydraulic fracturi ng event is shown below

Equation 32) 

### 185

, 907 , , stage stages i

i event fracing 

### t N LF HP EF

n E u u u u

u

where:

E fracing,event 

### is the exhaust emissions for pollutant i from a si ngle fracing event [ton/event]

EF i 

### is the emissions factor of pollutant i [g/hp-hr]

HP is the horsepower of the engine [hp]

LF is the load factor of the engine

N stages 

### is the number of stages per fracing event [stage/e vent]

t annual 

### is the duration of the fracturing stage [hr/stage]

n is the number of engines used per fracing event 907185 is the unit conversion factor g/ton

Extrapolation to county-level emissions

Frac pump emissions can be scaled up to the county level on the basis of horizontal spuds. It is assumed that hydraulic fracturing is performed in a ll horizontal spuds and thus the methodology for scaling up fracturing pump engine e missions is based on this surrogate as

shown below:

Equation 33) i event fracing event i TOTAL pumps frac 

## E

N E

, , , , , 

## u

where:December 2012



### 72

E frac,pump,TOTAL 

### is the total emissions from frac pump engines in t he county [ton/yr]

E fracing,event 

### is the total exhaust emissions from engines in a s ingle fracing event [ton/event]

N events 

### is the number of horizontal wells drilled in a par ticular year [spuds/yr]

Source category data fields within the tool

FIELD FIELD DESCRIPTION Units WORKSHEET TAB
HYDRAULIC_FRACTURE_HP Typical horsepower (HP) of a hydraulic
fracture engine HP BASIN_FACTORS

HYDRAULIC_FRACTURE_LOAD_FACTOR Typical load factor of a hydraulic
fracture engine Unitless BASIN_FACTORS

HYDRAULIC_FRACTURE_STAGES_WELL Number of stages per fracturing event COUNT BASIN_FACTORS

HYDRAULIC_FRACTURE_HR_STAGE Typical duration of the fracturing

stage Hours per

stage BASIN_FACTORS

HYDRAULIC_FRACTURE_TOTAL_DURATIO

N Total number of hours for fracturing Hours per

year BASIN_FACTORS

HYDRAULIC_FRACTURE_ENGINES_EVENT Number of fracturi ng engines used
per fracturing event COUNT BASIN_FACTORS

HYDRAULIC_FRACTURE_HP-HR_WELL Total horsepower-hour from hydraulic
fracturing per well HPHR/WELL BASIN_FACTORS

HYDRAULIC_FRACTURE_ALT_EF Alternative value, if ava ilable, for
hydraulic fracturing G/HP-HR BASIN_FACTORS



### 6.2.11 Fugitive Leaks

Calculation Sheets: FUGITIVE_GAS_CON_2310021501; FU GITIVE_GAS_FLANGES_2310021502; FUGITIVE_GAS_OEL_2310021503; FUGITIVE_GAS_VALVES_23 10021505; FUGITIVE_GAS_COMSEAL_2310021506; FUGITIVE_OIL_CON_2 310021501; FUGITIVE_OIL_FLANGES_2310021502; FUGITIVE_OIL_OEL_2 310021503; FUGITIVE_OIL_VALVES_2310021505;

This source category refers to leaking emissions of produced gas that escape through well site and pipeline components such as connectors, flanges , open-ended lines and valves. As a revision to the CENRAP study (Bar-Ilan, et al., 200 8), compressor wet seals fugitive emissions have been added to this inventory. It must be noted that this source category refers only to fugitive emissions components located at the wellhe ad and that large transmission pipeline fugitives and other midstream fugitives sources are not part of this analysis.

Fugitive emissions for an individual typical well a re estimated according to Equation 34:

Equation 34) 

# ¦ u u u

i j

annual i i j fugitive 

### Y

t N EF E

,



### where:

E fugitive,j 

### is the fugitive emissions for a single typical wel l for pollutant j [ton/yr/well]

EF i 

### is the emission factor of TOC for a single compone nt i [kg/hr/component]December 2012



### 73

N i 

### is the total number of components of type i

t annual 

### is the annual number of hours the well is in opera tion [8760 hr/yr]

Y j 

### is the mass ratio of pollutant j to TOC in the vented gas

In addition, fugitive leaks from wellhead compresso r seals can be estimated from the following
equation

Equation 35)

gas lateral wellhead

gas vented

CH fug compressor 

### W N f

T MW R t

V P E u 
u  ̧  ̧  ̧  ̧

1 ·

 ̈  ̈  ̈  ̈

© §

u

u u u  ̧ 1 ·  ̈ © § u

u

 

### 1000 * 907185 /1

24 10 5.3 5 4

, ,



### where:

E compressor,fug,CH4 

### is the county-wide methane fugitive emissions from compressor seals [ton/yr]

P is atmospheric pressure [1 atm]

V vented 

### is the volume of leaked gas per compressor [SCF/co mpressor/day]

t is the annual hours of operation for wellhead compr essors [hrs/yr]

R is the universal gas constant [0.082 L-atm/mol-K]

MW gas 

### is the molecular weight of the pollutant [g/mol]

T is the atmospheric temperature [298 K] f wellhead 

### is the fraction of wells with wellhead compressors

N lateral 

### is the number of gas wells served by a lateral com pressor engine

W gas 

### is the county-wide number of gas wells

3.5x10 -5 

### is the unit conversion factor MCF/L 907185 is the unit conversion factor g/ton 1000 is the unit conversion factor SCF/MCF 24 is the unit conversion factor hr/day

To estimate emissions from other pollutants (VOC, C O2, H2S) the following equation may be

used:

Equation 36)

4 4 , , , 4 CH i

CH i fug compressor i fug compressor 

## M M

MW MW E E

CH 

## u u

where:

E compressor,fug,i



### is the county-wide compressor fugitive emissions f or pollutant i [ton/yr]

EF compressor,fug,CH4 

### is the compressor fugitive emissions for methane [t on CH4/yr]

MW i 

### is the molecular weight of pollutant i [lb/lb-mol]

MW CH4 

### is the molecular weight of methane [lb/lb-mol]

M CH4 

### is the mole percent of methane in the local gas [% ]

M i 

### is the mole percent of pollutant in the local gas [%]December 2012



### 74

Extrapolation to county-level emissions

County-wide fugitive emissions from well-site pipin g components are estimated according to
Equation 37

Equation 37) well j fugitive TOTAL fugitive 

### N

E E u

, ,



### where:

E fugitive,TOTAL 

### is the total fugitive emissions from well-site pip ing components in the county [ton/yr]

E fugitive,j 

### is the fugitive emissions for a single well of pol lutant j [ton/yr/well] (from Equation 35)

N well 

### is the total number of active wells in the county [wells]

Total county-wide fugitive emissions are the sum ofcompressor seals emissions and bycomponent fugitive emissions.

Source category data fields within the tool

FIELD FIELD DESCRIPTION Units WORKSHEET TAB
FUG_VALVES_GAS Count of valves per gas service COUN T BASIN_FACTORS

FUG_VALVES_HO Count of valves per heavy oil service COUNT BASIN_FACTORS

FUG_VALVES_LO Count of valves per light oil service COUNT BASIN_FACTORS
FUG_VALVES_WO Count of valves per water/oil service COUNT BASIN_FACTORS
FUG_PUMP_SEALS_GAS Count of pump seals per gas servi ce COUNT BASIN_FACTORS

FUG_PUMP_SEALS_HO Count of pump seals per heavy oil

service COUNT BASIN_FACTORS

FUG_PUMP_SEALS_LO Count of pump seals per light oil

service COUNT BASIN_FACTORS

FUG_PUMP_SEALS_WO Count of pump seals per water/oil

service COUNT BASIN_FACTORS

FUG_OTHERS_GAS Count of compressor seals per gas

service COUNT BASIN_FACTORS

FUG_OTHERS_HO Count of compressor seals per heavy

oil service COUNT BASIN_FACTORS

FUG_OTHERS_LO Count of compressor seals per light o il

service COUNT BASIN_FACTORS

FUG_OTHERS_WO Count of compressor seals per
water/oil service COUNT BASIN_FACTORS

FUG_CONN_GAS Count of connectors per gas service CO UNT BASIN_FACTORS

FUG_CONN_HO Count of connectors per heavy oil

service COUNT BASIN_FACTORS

FUG_CONN_LO Count of connectors per light oil

service COUNT BASIN_FACTORSDecember 2012



### 75

FIELD FIELD DESCRIPTION Units WORKSHEET TAB
FUG_CONN_WO Count of connectors per water/oil

service COUNT BASIN_FACTORS

FUG_FLANGES_GAS Count of flanges per gas service CO UNT BASIN_FACTORS

FUG_FLANGES_HO Count of flanges per heavy oil servi ce COUNT BASIN_FACTORS

FUG_FLANGES_LO Count of flanges per light oil servi ce COUNT BASIN_FACTORS
FUG_FLANGES_WO Count of flanges per water/oil servi ce COUNT BASIN_FACTORS

FUG_OEL_GAS Count of open-ended lines per gas

service COUNT BASIN_FACTORS

FUG_OEL_HO Count of open-ended lines per heavy

oil service COUNT BASIN_FACTORS

FUG_OEL_LO Count of open-ended lines per light oil

service COUNT BASIN_FACTORS

FUG_OEL_WO Count of open-ended lines per
water/oil service COUNT BASIN_FACTORS

FUG_ANNUAL_HRS Annual operating hours for fugitive

components Hours per year BASIN_FACTORS

FUG_GW_VOC_TOC Fraction of VOC in Total organic
compounds at gas wells Unitless BASIN_FACTORS

FUG_GW_H2S_TOC Fraction of Hydrogen sulfide in Tota l
organic compounds at gas wells Unitless BASIN_FACTORS

FUG_GW_CO2_TOC Fraction of Carbon dioxide in Total
organic compounds at gas wells Unitless BASIN_FACTORS

FUG_GW_CH4_TOC Fraction of Methane dioxide in Total
organic compounds at gas wells Unitless BASIN_FACTORS

FUG_GW_BENZ_TOC Fraction of Benzene dioxide in Tota l
organic compounds at gas wells Unitless BASIN_FACTORS

FUG_GW_ETHYLBENZ_TOC Fraction of Ethylbenzene dioxide in
Total organic compounds at gas wells Unitless BASIN_FACTORS

FUG_GW_TOLUENE_TOC Fraction of Toluene dioxide in T otal
organic compounds at gas wells Unitless BASIN_FACTORS

FUG_GW_XYLENE_TOC Fraction of Xylene dioxide in Total
organic compounds at gas wells Unitless BASIN_FACTORS

FUG_OW_VOC_TOC Fraction of VOC in Total organic
compounds at oil wells Unitless BASIN_FACTORS

FUG_OW_H2S_TOC Fraction of Hydrogen sulfide in Tota l
organic compounds at oil wells Unitless BASIN_FACTORS

FUG_OW_CO2_TOC Fraction of Carbon dioxide in Total
organic compounds at oil wells Unitless BASIN_FACTORS

FUG_OW_CH4_TOC Fraction of Methane in Total organic
compounds at oil wells Unitless BASIN_FACTORS

FUG_OW_BENZ_TOC Fraction of Benzene in Total organic
compounds at oil wells Unitless BASIN_FACTORSDecember 2012



### 76

FIELD FIELD DESCRIPTION Units WORKSHEET TAB
FUG_OW_ETHYLBENZ_TOC Fraction of Ethylbenzene in To tal
organic compounds at oil wells Unitless BASIN_FACTORS

FUG_OW_TOLUENE_TOC Fraction of Toluene in Total org anic
compounds at oil wells Unitless BASIN_FACTORS

FUG_OW_XYLENE_TOC Fraction of Xylene in Total organ ic
compounds at oil wells Unitless BASIN_FACTORS

FUG_COMP_SEAL_CH4_LEAKING Methane leaking rate per co mpressor daily SCF/HR/

COMPRESSOR BASIN_FACTORS

FRACT_WELL_COMPRESS Fraction of wells serviced by we llhead

compressors Unitless BASIN_FACTORS

NUM_WELL_COMPRESS Number of wells serviced by a sing le
lateral compressor COUNT BASIN_FACTORS

FUG_COMP_SEAL_HOURS_OP Annual operating hours for

compressors Hours per year BASIN_FACTORS

FUG_GAS_LHV Heating value of the leaked gas at
compressor seals BTU/SCF BASIN_FACTORS

FUG_GAS_MW Molecular weight of the leaked gas at
compressor seals G/MOL BASIN_FACTORS

FUG_GAS_VOC_WT_FRACT VOC fraction in leaked gas at
compressor seals Unitless BASIN_FACTORS

FUG_GAS_H2S_WT_FRACT Hydrogen sulfide fraction in l eaked gas
at compressor seals Unitless BASIN_FACTORS

FUG_GAS_CO2_WT_FRACT Carbon dioxide fraction in lea ked gas at
compressor seals Unitless BASIN_FACTORS

FUG_GAS_CH4_WT_FRACT Methane fraction in leaked gas at
compressor seals Unitless BASIN_FACTORS

FUG_GAS_BENZ_WT_FRACT Benzene fraction in leaked gas at
compressor seals Unitless BASIN_FACTORS

FUG_GAS_ETHYLBENZ_WT_FRACT Ethylbenzene fraction in leaked gas at
compressor seals Unitless BASIN_FACTORS

FUG_GAS_TOLUENE_WT_FRACT Toluene fraction in leaked gas at
compressor seals Unitless BASIN_FACTORS

FUG_GAS_XYLENE_WT_FRACT Xylene fraction in leaked g as at
compressor seals Unitless BASIN_FACTORS

VOC_MOL_PCT VOC molar PCT Value Unitless BASIN_FACTO RS

CO2_MOL_PCT Carbon dioxide molar PCT Value Unitless BASIN_FACTORS

CH4_MOL_PCT Methane molar PCT Value Unitless BASIN_F ACTORS

H2S_MOL_PCT Hydrogen sulfide molar PCT Value Unitles s BASIN_FACTORS
VOC_MOL_WT Molecular weight of VOC G/MOL BASIN_FACTORSDecember 2012



### 77

6.2.12 Heaters

Calculation sheets: HEATERS_OIL_2310010100; HEATERS _GAS_2310021100

This category refers to natural gas-fired external combustors used in oil and gas production facilities to provide heat input to separator (sepa rator heaters) or to provide heat to tanks (tank heaters). It must be noted that this category does not refer to reboilers used in dehydrators as those emissions are captured in the dehydrator sour ce category. The basic methodology for estimating emissions for all pollutants except SO 2 

### for a single heater is shown in Equation 38. Local fuel gas properties will vary between gas wel ls and oil wells; hence emissions were estimated separately for this category. Due to limi ted field data for this category, all other parameters unrelated to local gas composition were assumed to be the same for gas and oil

wells.

Equation 38) 2000 u u u u

local annual heater heater
heater 

### HV hc t Q EF E



### where:

E heater 

### is the emissions from a given heater [ton/yr]

EF heater 

### is the emission factor for a heater for a given pol lutant [lb/million SCF]

Q heater 

### is the heater MMBTU/hr rating [MMBTU rated 

### /hr]

HV local 

### is the local natural gas heating value [BTU local 

### /SCF]

t annual 

### is the annual hours of operation [hr/yr]

hc is a heater cycling fraction to account for the fr action of operating hours that the heater is firing (if not available, hc=1) 2000 is the unit conversion factor lb/ton

The methodology for estimating SO 2 

### emissions from heaters requires first estimating t he mass of gas combusted in the heater, and then uses the m ass fraction of H 2 

### S in the gas and the assumption that all H 2 

### S is converted to SO 2 

### . This methodology is described in Equation 39

Equation 39)
 ̧  ̧  ̧  ̧  ̧

1 ·

 ̈  ̈  ̈  ̈  ̈

© §

 ̧  ̧ 1 ·  ̈  ̈ © §

u

u  ̧ 1 ·  ̈ © § u u u
u u

035 .0 907185 2

2

2 , 

### T MW R P

HV hc t Q f E

gas local annual heater S H

SO heater



### where:

2

, SO heater 

### E 

### is the SO 2 

### emissions from a given heater [ton-SO 2 

### /yr]

2 SO 

### f 

### is the mass fraction of H 2 

### S in the gas

Q heater 

### is the heater MMBTU/hr rating [MMBTU rated 

### /hr]

HV local 

### is the local natural gas heating value [MMBTU local 

### /scf]

t annual 

### is the annual hours of operation [hr/yr]December 2012



### 78

hc is a heater cycling fraction to account for the fr action of operating hours that the heater is firing

P is atmospheric pressure [1 atm]

R is the universal gas constant [0.082 L-atm/mol-K]

MW gas 

### is the molecular weight of the gas [g/mol]

3.5x10 -3 

### is the unit conversion factor SCF/L 907185 is the unit conversion factor g/ton 1000 is the unit conversion factor SCF/MCF

Extrapolation to county-level emissions

County-wide heater emissions are estimated by deter mining the typical number of heaters per well and scaling up by well count. This is shown i n Equation 40:

Equation 40)
TOTAL heater heater TOTAL heater 

### W

N E E u

u

,



### where:

E heater,TOTAL 

### is the total heater emissions in a county for a sp ecific pollutant [ton/yr]

E heater 

### is the total emissions from a single heater for a specific pollutant [ton/yr]

W TOTAL 

### is the total number of wells in the county

N heater 

### is the typical number of heaters per well througho ut in the basin

Source category data fields within the tool

FIELD FIELD DESCRIPTION Units WORKSHEET TAB
NUM_HEATERS_TYPICAL Typical number of heaters at a well COUNT BASIN_FACTORS

HEATER_RATING Heater rating MMBTU/HR BASIN_FACTORS

HEATER_ANNUAL_OP_HOURS Typical number of hours oper ated for

heaters Hours per year BASIN_FACTORS

HEATER_CYCLING Fraction to account for the fraction of
operating hours that the heater is firing Unitless BASIN_FACTORS

HEATER_GASWELL_H2S_FRAC Fraction of hydrogen sulfid e in the
natural gas Unitless BASIN_FACTORS

HEATER_GASWELL_LOCAL_HV Heating value of the natura l gas used for

fuel BTU/SCF BASIN_FACTORS

HEATER_GASWELL_MW Molecular weight of the gas emitted
from the gas well heater G/MOL BASIN_FACTORS

HEATER_OILWELL_H2S_FRAC Fraction of hydrogen sulfid e in the oil Unitless BASIN_FACTORS

HEATER_OILWELL_LOCAL_HV Heating value of the oil us ed for fuel BTU/SCF BASIN_FACTORS

HEATER_OILWELL_MW Molecular weight of the gas emitted

from the oil well heater G/MOL BASIN_FACTORSDecember 2012



### 79

6.2.13 Loading Emissions

Calculation Sheets: LOADING_COND_2310021030; LOADIN G_CRUDE_2310011201

This category refers to loading losses that occur w hen transferring hydrocarbon liquids, crude oil or condensate, from storage tanks to cargo truc ks. The emissions will vary by the gas speciation of the working losses; hence emissions w ere calculated separately for each hydrocarbon liquid. Equations 41-44 may be used for both categories (SCCs). The loading loss rate is estimated following Equation 41:

Equation 41)  ̧ 1 ·  ̈ © §

u u u u 1000 46. 12 T M

V S L

where:

L is the loading loss rate [lb/1000gal]

S is the saturation factor taken from AP-42 default values based on operating mode (here assumed as submerged loading: dedicated normal serv ice)

V is the true vapor pressure of the liquid loaded [p sia]

M is the molecular weight of the vapor [lb/lb-mole]

T is the temperature of the bulk liquid [ o 

### R]

VOC truck loading emissions are then estimated by E quation 42 which is dependent on the VOC fraction in the gas. When available, basin-specific working/breathing gas compositions from condensate/crude oil storage tanks were used in Equ ations 42-44; however when basin-level data was limited or unavailable, produced gas analy ses were used to speciate emissions from each pollutant.

Equation 42) ܧ ௔௢௟ௗ௜௡௚

, ௏ை஼ 

### = ௅

ଵ଴଴଴ 

### × ܻ

௩௢௖ 

### × ସଶ

ଶ଴଴଴



### where:

E loading 

### are the VOC tank loading emissions [ton-VOC/bbl]

L is the loading loss rate [lb/1000gal]

Y VOC 

### is the weight fraction of VOC in the vapor in the l iquid loaded

42 is a unit conversion [gal/bbl]

2000 is a unit conversion [lbs/ton]

CO 2 

### and CH 4 

### emissions are calculated based on Equations 43-44:

Equation 43) ܧ ௔௢௟ௗ௜௡௚

, ஼ுସ 

### = ܧ ௔௢௟ௗ௜௡௚

, ௏ை஼ 

### × ௪௘௜௚௛௧ ௙௥௔௖௧௜௢௡ ಴ಹర ௪௘௜௚௛௧ ௙௥௔௖௧௜௢௡ ೇೀ಴ 

### Equation 44) ܧ ௔௢௟ௗ௜௡௚

, ஼ைଶ 

### = ܧ ௔௢௟ௗ௜௡௚

, ௏ை஼ 

### × ௪௘௜௚௛௧ ௙௥௔௖௧௜௢௡ ಴ೀమ ௪௘௜௚௛௧ ௙௥௔௖௧௜௢௡ ೇೀ಴



### where:

E loading,CO2 

### is the total loading CO 2 

### emissions per barrel of liquid [ton/bbl]December 2012



### 80

E loadingCH4 

### is the total loading CH 4 

### emissions per barrel of liquid [ton/bbl] Weight fractions of each pollutant in the vapor losses from the liquid loaded

Extrapolation to county-level emissions

Annual emissions per pollutant i from condensate lo ading were scaled to county-level by annual condensate production per Equation 45:

Equation 45) ܧ ௧௔௡௞ ௟௢௔ௗ௢௨௧

, ௜ 

### = ܧ ௔௢௟ௗ௜௡௚

, ௜ 

### × ܵ ௕௕௟ ௖௢௡ௗ௘௡௦௔௧௘ 

### × ܨ ௧௥௨௖௞௘ௗ



### where:

E tank loadout, i



### is the annual county-level emissions for pollutant i from condensate tank loadout [ton/yr]

E loading, i 

### is the emissions for pollutant i from loading per barrel [ton/bbl]

S bbl condensate 

### is the total annual of barrels condensate produced county-wide [bbl/yr]

F pipeline 

### is the fraction of condensate production that is de livered by truck

Annual emissions per pollutant i from oil loading w ere scaled to county-level by annual oil production per Equation 46:

Equation 46) ܧ ௧௔௡௞ ௟௢௔ௗ௢௨௧

, ௢௜௟

, ௜ 

### = ܧ ௔௢௟ௗ௜௡௚

, ௜ 

### × ܵ ௕௕௟ ௢௜௟ 

### × ܨ ௧௥௨௖௞௘ௗ



### where:

E tank loadout, i



### is the annual county-level emissions for pollutant i from crude oil tank load-out [ton/yr]

E loading, i 

### is the emissions for pollutant i from loading per barrel [ton/bbl]

S bbl oil 

### is the total annual oil produced county-wide [bbl/ yr]

F pipeline 

### is the fraction of oil production that is delivered by truck

Source category data fields within the tool

FIELD FIELD DESCRIPTION Units WORKSHEET TAB

LOADING_OP_MODE Typical operating mode for liquids loading TYPE BASIN_FACTORS
LOADING_SAT_FAC Saturation factor based on operatin g

mode Unitless BASIN_FACTORS

LOADING_FRAC_COND_TRUCK Fraction of condensate load ing to trucks Unitless BASIN_FACTORS

LOADING_FRAC_CRUDE_TRUCK Fraction of crude oil load ing to trucks Unitless BASIN_FACTORS

LOADING_COND_BULK_LIQ_T Temperature of the bulk con densate R BASIN_FACTORS

LOADING_COND_VOC_WT_PCT Fraction of VOC in the vapo r of loaded

condensate Unitless BASIN_FACTORS

LOADING_COND_CO2_WT_PCT Fraction of Carbon dioxide in the vapor of

loaded condensate Unitless BASIN_FACTORS

LOADING_COND_CH4_WT_PCT Fraction of Methane in the v apor of

loaded condensate Unitless BASIN_FACTORS

LOADING_COND_MW_VAPOR Molecular weight of condensate vapor G/MOL BASIN_FACTORSDecember 2012



### 81

FIELD FIELD DESCRIPTION Units WORKSHEET TAB
LOADING_COND_PRESS_VAPOR True vapor pressure of the condensate PSIA BASIN_FACTORS

LOADING_OIL_BULK_LIQ_T Temperature of the bulk crud e oil R BASIN_FACTORS

LOADING_OIL_VOC_WT_PCT Fraction of VOC in the vapor of loaded

crude oil Unitless BASIN_FACTORS

LOADING_OIL_CO2_WT_PCT Fraction of Carbon dioxide i n the vapor of

loaded crude oil Unitless BASIN_FACTORS

LOADING_OIL_CH4_WT_PCT Fraction of Methane in the va por of

loaded crude oil Unitless BASIN_FACTORS

LOADING_OIL_MW_VAPOR Molecular weight of crude oil va por G/MOL BASIN_FACTORS

LOADING_OIL_PRESS_VAPOR True vapor pressure of the crude oil PSIA BASIN_FACTORS

LOADING_COND_BENZ_VOC Benzene ratio to VOC being em itted
during condensate loading Unitless BASIN_FACTORS

LOADING_COND_ETHYLBENZ_VOC Ethylbenzene ratio to VO C being emitted
during condensate loading Unitless BASIN_FACTORS

LOADING_COND_TOLUENE_VOC Toluene ratio to VOC being emitted during
condensate loading Unitless BASIN_FACTORS

LOADING_COND_XYLENE_VOC Xylene ratio to VOC being e mitted during
condensate loading Unitless BASIN_FACTORS

LOADING_COND_METHANE_VOC Methane ratio to VOC being e mitted
during condensate loading Unitless BASIN_FACTORS

LOADING_COND_H2S_VOC Hydrogen sulfide ratio to VOC being
emitted during condensate loading Unitless BASIN_FACTORS

LOADING_CRUDE_BENZ_VOC Benzene ratio to VOC being e mitted
during crude oil loading Unitless BASIN_FACTORS

LOADING_CRUDE_ETHYLBENZ_VOC Ethylbenzene ratio to V OC being emitted
during crude oil loading Unitless BASIN_FACTORS

LOADING_CRUDE_TOLUENE_VOC Toluene ratio to VOC bein g emitted during
crude oil loading Unitless BASIN_FACTORS

LOADING_CRUDE_XYLENE_VOC Xylene ratio to VOC being emitted during
crude oil loading Unitless BASIN_FACTORS

LOADING_CRUDE_METHANE_VOC Methane ratio to VOC being emitted
during crude oil loading Unitless BASIN_FACTORS

LOADING_CRUDE_H2S_VOC Hydrogen sulfide ratio to VOC being
emitted during crude oil loading Unitless BASIN_FACTORS



### 6.2.14 Gas-Actuated Pumps

Calculation sheets: GAS_ACT_GAS_2310121401; GAS_ACT _OIL_2310111401.

Gas-actuated pumps refer to small gas-driven plunge r pumps used at oil and gas production sites, to provide a constant supply of chemicals or lubricants to specific flow lines or equipment. These are regularly used in sites where electric po wer is unavailable. As part of their operation, gas-driven pumps vent part of the driving gas to th e atmosphere, making them a VOC andDecember 2012



### 82

methane emissions source. Two types of gas-actuated pumps were considered: Kimray pumps and chemical injection pumps (CIP). For oil wells o nly CIPs are assumed to be used. Annual vented gas rates per well from Kimray pumps are est imated following Equation 47:

Equation 47)


###  ̧  ̧ 1 ·  ̈  ̈ © §

u

u u  ̧ 1 ·  ̈ © §

u u u

 5 4

4

, 

### 10 5.3 1000 907185 T MW R P Q EF E

gas kimray CH

CH kimray



### where:

E kimray,CH4 

### is the per-well methane emissions from Kimray pump s at gas wells [tons-CH4/wellyr]

EF CH4 

### is the methane emissions factor for a Kimray pump per unit throughput [SCFCH4/MMSCF]

Q kimray 

### is the average gas pumped per well annually with K imray pumps [MMSCF/well-yr]

P is the atmospheric pressure [1 atm]

R is the universal gas constant [0.082 L-atm/mol-K]

MW gas 

### is the molecular weight of the gas [g/mol]

T is the atmospheric temperature [298 K]

3.5x10 -5 

### is the unit conversion factor MCF/L 907185 is the unit conversion factor g/ton 1000 is the unit conversion factor SCF/MCF

Emissions from CIPs are estimated based on equation 48:

Equation 48)  ̧ 1 ·  ̈ © §

u

u u  ̧ 1 ·  ̈ © §

u u u u

 5 4

4

, 

### 10 5.3 1000 24 907185 T MW R P t N EF E

methane CIP

CIP CH

CH CIP



### where:

E CIP,CH4 

### is the per-well methane emissions from CIP pumps a t gas wells [tons-CH4/well-yr]

EF CH4 

### is the methane emissions factor for a CIP pump [SC F-CH4/pump/day]

N CIP 

### is the average number of CIPs per well [pump/well]

t CIP 

### is the regular operation time for chemical injecti on pumps [hrs/yr]

P is the atmospheric pressure [1 atm]

R is the universal gas constant [0.082 L-atm/mol-K]

MW methane 

### is the molecular weight of methane [g/mol]

T is the atmospheric temperature [298 K]

3.5x10 -5 

### is the unit conversion factor MCF/L 907185 is the unit conversion factor g/ton 1000 is the unit conversion factor SCF/MCFDecember 2012



### 83

To estimate emissions from other pollutants (VOC, C O2, H2S, HAPs) from Kimray and CIP
pumps, the following equation may be used:

Equation 49)

4 4 , 4 CH i

CH i

pump i pump 

## M M

MW MW E E

CH 

## u

u

where:

E pump,i 

### is the emissions for pollutant i per well from CIP s or Kimray Pumps [ton/well-yr]

EF pump,CH4 

### is the methane emissions from CIPs or Kimray Pumps [ton CH4/well-yr] (from equations 47 or 48)

MW i 

### is the molecular weight of pollutant i [lb/lb-mol]

MW CH4 

### is the molecular weight of methane [lb/lb-mol]

M CH4 

### is the mole percent of methane in the local gas ve nted from the pump [%]

M i 

### is the mole percent of pollutant in the local gas vented from the pump [%]

Extrapolation to county-level emissions

To estimate county-wide annual emissions from gas-a ctuated pumps for each pollutant, the scaling surrogate used is well counts, according to equation 50:

Equation 50)

ܧ ீ௉஺

, ௜ 

### = ൣ ) ܧ ஼ூ௉

, ௜ 

### + ܧ ௔௥௠௜௞௬

, ௜ 

### ) × ܵ ௪௘௟௟ ௖௢௨௡௧ 

### ൧

௚௔௦ ௪௘௟௟௦ 

### + ܧൣ ௉ூ஼

, ௜ 

### × ܵ ௪௘௟௟ ௖௢௨௡௧ 

### ൧

௢௜௟ ௪௘௟௟௦



### where:

E GAP, i 

### is the annual county-wide emissions for pollutant i from gas-actuated pumps [ton/yr]

E kimray, i 

### is the emissions from kimray pumps per well type ( gas or oil) [ton/yr-well]

E CIP, i 

### is the emissions from chemical injection pumps per well type (gas or oil) [ton/yr-well]

S well count 

### is the number of active wells (gas or oil) in a pa rticular county [wells]

Source category data fields within the tool

FIELD FIELD DESCRIPTION Units WORKSHEET

TAB
ACT_GAS_KIM_CH4_VENT_RATE Methane vent rate for gas wells

using Kimray pumps SCF/MMSCF BASIN_FACTORS

ACT_GAS_KIM_AVG_GAS_PUMPED_WELL_YR Average gas pumpe d per well
annually with Kimray pumps per
unit throughput MMSCF/WELL/YR BASIN_FACTORS

ACT_GAS_CIP_CH4_VENT_RATE Methane vent rate for gas wells

using CIP pumps SCF/MMSCF BASIN_FACTORS

ACT_GAS_CIP_HRS_OP Average gas pumped per gas well
annually with CIP pumps per unit
throughput MMSCF/WELL/YR BASIN_FACTORSDecember 2012



### 84

FIELD FIELD DESCRIPTION Units WORKSHEET

TAB
ACT_GAS_CIP_AVG_NUM_PUMP_WELL Average number of CIP pumps per gas well COUNT/WELL BASIN_FACTORS

ACT_OIL_CIP_CH4_VENT_RATE Methane vent rate for oil wells

using CIP pumps SCF/MMSCF BASIN_FACTORS

ACT_OIL_CIP_HRS_OP Average gas pumped per oil well
annually with CIP pumps per unit
throughput MMSCF/WELL/YR BASIN_FACTORS

ACT_OIL_CIP_AVG_NUM_PUMP_WELL Average number of CIP pumps per

oil well COUNT/WELL BASIN_FACTORS

ACT_GAS_MW_GAS Molecular weight of the gas emitted
by gas-actuated pumps at gas wells G/MOL BASIN_FACTORS

ACT_GAS_MOL_PCT_VOC VOC fraction of gas emitted by g asactuated pumps at gas wells Unitless BASIN_FACTORS

ACT_GAS_MOL_PCT_H2S Hydrogen sulfide fraction of gas
emitted by gas-actuated pumps at
gas wells Unitless BASIN_FACTORS

ACT_GAS_MOL_PCT_CO2 Carbon dioxide fraction of gas
emitted by gas-actuated pumps at
gas wells Unitless BASIN_FACTORS

ACT_GAS_MOL_PCT_CH4 Methane fraction of gas emitted b y gas-actuated pumps at gas wells Unitless BASIN_FACTORS

ACT_GAS_VOC_MW Molecular weight of the VOC
emitted by gas-actuated pumps at
gas wells G/MOL BASIN_FACTORS

ACT_OIL_MW_GAS Molecular weight of the gas emitted
by gas-actuated pumps at gas wells G/MOL BASIN_FACTORS

ACT_OIL_MOL_PCT_VOC VOC fraction of gas emitted by g asactuated pumps at oil wells Unitless BASIN_FACTORS

ACT_OIL_MOL_PCT_H2S Hydrogen sulfide fraction of gas
emitted by gas-actuated pumps at

oil wells Unitless BASIN_FACTORS

ACT_OIL_MOL_PCT_CO2 Carbon dioxide fraction of gas
emitted by gas-actuated pumps at

oil wells Unitless BASIN_FACTORS

ACT_OIL_MOL_PCT_CH4 Methane fraction of gas emitted b y gas-actuated pumps at oil wells Unitless BASIN_FACTORS

ACT_OIL_VOC_MW Molecular weight of the VOC
emitted by gas-actuated pumps at

oil wells G/MOL BASIN_FACTORS

ACT_OIL_BENZ_VOC Benzene ratio to VOC being emitted
by gas-actuated pumps at oil wells Unitless BASIN_FACTORSDecember 2012



### 85

FIELD FIELD DESCRIPTION Units WORKSHEET

TAB
ACT_OIL_ETHYLBENZ_VOC Ethylbenzene ratio to VOC bei ng emitted by gas-actuated pumps at

oil wells Unitless BASIN_FACTORS

ACT_OIL_TOLUENE_VOC Toluene ratio to VOC being emit ted
by gas-actuated pumps at oil wells Unitless BASIN_FACTORS

ACT_OIL_XYLENE_VOC Xylene ratio to VOC being emitte d
by gas-actuated pumps at oil wells Unitless BASIN_FACTORS

ACT_OIL_METHANE_VOC Methane ratio to VOC being
emitted by gas-actuated pumps at

oil wells Unitless BASIN_FACTORS

ACT_OIL_H2S Hydrogen sulfide ratio to VOC being
emitted by gas-actuated pumps at

oil wells Unitless BASIN_FACTORS

ACT_GAS_BENZ_VOC Benzene ratio to VOC being emitted
by gas-actuated pumps at gas wells Unitless BASIN_FACTORS

ACT_GAS_ETHYLBENZ_VOC Ethylbenzene ratio to VOC bei ng emitted by gas-actuated pumps at
gas wells Unitless BASIN_FACTORS

ACT_GAS_TOLUENE_VOC Toluene ratio to VOC being emit ted
by gas-actuated pumps at gas wells Unitless BASIN_FACTORS

ACT_GAS_XYLENE_VOC Xylene ratio to VOC being emitte d
by gas-actuated pumps at gas wells Unitless BASIN_FACTORS

ACT_GAS_METHANE_VOC Methane ratio to VOC being
emitted by gas-actuated pumps at
gas wells Unitless BASIN_FACTORS

ACT_GAS_H2S Hydrogen sulfide ratio to VOC being
emitted by gas-actuated pumps at
gas wells Unitless BASIN_FACTORS



### 6.2.15 Mud Degassing

Calculation Sheets: MUD_DEG_GAS_2310121100; MUD_DEG _OIL_2310111100

Drilling mud degassing refers to the practice of ex tracting the entrained gas from the drilling mud once it is outside of the wellbore. During this process VOCs and methane (and other pollutants in the gas) are vented to the atmosphere . National default emissions factors for mud degassing are available from The Climate Registry R eporting Protocol:December 2012



### 86

Table 6-2. National default emissions factors for mud degassing by mud base.

Emission Source Emission Factor Units 7 Emission Factor Units 8

Mud degassing – water-based

mud 881.84 lbs THC / drilling day 0.2605 tonnes CH4/ d rilling day

Mud degassing – oil-based mud 198.41 lbs THC / dril ling day 0.0586 tonnes CH4/ drilling day
Mud degassing – synthetic mud 198.41 lbs THC / dril ling day 0.0586 tonnes CH4/ drilling day



### Water-based mud emissions factors were assumed as a default conservative value, but this parameter may be updated in the tool by the User wi th other factors in Table 6-2 or any basinspecific factor that may be available. This can be done in the EMISSIONS_FACTOR tab of the

tool. To account for the use of different mud bases within a region, the methane emissions factor may be estimated as a weighted average based on a usage fraction of each mud type

within a basin.

Applying the local-gas methane mass fraction to the mud degassing emission factors provides the site-representative emissions as shown in equat ion 51. Because the mud entrained gas is the gas coming out directly from the wellbore durin g drilling, produced gas compositions by well type are used to characterize these emissions. Equations 51-52 are applicable to both oil and gas wells mud degassing emissions, however gas compositions and surrogate values (spuds) will vary for each well type.

Equation 51) 

## 85. 83 102 .1 4
4

, 4

, , CH
CH mud drill CH vent mud 

## M

EF N E u u u

where:

E mud,vent,CH4 

### is the mud degassing emissions for methane per spu d [ton/spud]

EF mud,CH4 

### is the emissions factor for methane [ton CH4/drilli ng days]

N drill 

### is the number of drilling days per spud [drilling d ays/spud]

83.85 is the mole percent of methane from the vented gas used to derive the emissions factor (EF)

M CH4 

### is the mole percent of methane in the local gas ve nted during mud degassing [%] (if basin-specific methane emissions factor is used, M= 83.85)

1.102 is the conversion of tonnes to short tons

To estimate emissions from other pollutants in the vented gas Equation 52 may be used:

7 Wilson, Darcy, Richard Billings, Regi Oommen, and Roger Chang, Eastern Research Group, Inc. Year 2005 Gulfwide Emission Inventory Study, U.S. Department of the In terior, Minerals Management Services, Gulf of Mexico O CS Region, New Orleans, December 2007, Section 5.2.10.

8 Based on gas content of 65.13 weight percent CH4, derived from sample data provided in the original s ource of the emission factors. Original sample data is as fo llows, in terms of mole%: 83.85% CH4, 5.41% C2H6, 6 .12% C3H8, 3.21% C4H10, and 1.40% C5H12 (Wilson et al., 2007)December 2012



### 87

Equation 52)

4 4 , , , 4 CH i

CH i

vent mud i vent mud 

## M M

MW MW E E

CH 

## u

u

where:

E mud,vent,i 

### is the mud degassing emissions for pollutant i per spud [ton/spud]

EF mud,ven6,CH4 

### is the vented emissions for methane [ton CH4/spud]

MW i 

### is the molecular weight of pollutant i [lb/lb-mol]

MW CH4 

### is the molecular weight of methane [lb/lb-mol]

M CH4 

### is the mole percent of methane in the local gas ve nted during mud degassing [%]

M i 

### is the mole percent of pollutant in the local gas vented during mud degassing [%]

Extrapolation to county-level emissions

To estimate county-wide annual emissions, mud degas sing emissions by spud are scaled with the county-wide count of drilling events (spuds), a ccording to Equation 53:

Equation 53) ܧ ௠௨ௗ

, ௩௘௡௧

, ்ை்஺௅ ௜ 

### = ܧ ௠௨ௗ

, ௩௘௡௧

, ௜ 

### × ܵ

௦௣௨ௗ௦



### where:

E mud,vent,TOTAL,i



### is the annual county-wide emissions for pollutant i from mud degassing [ton/yr]

E mud,vent, i 

### is the emissions from mud degassing from a drillin g event [ton/spud]

S spuds 

### is the number of wells drilled in a county for a p articular year [spud/yr]

Source category data fields within the tool

FIELD FIELD DESCRIPTION Units WORKSHEET TAB
MUD_AVG_DRILL_DAYS_SPUD Average number of drilling d ays per spud DAYS/SPUD BASIN_FACTORS

MUD_BASED_USED Mud type TYPE BASIN_FACTORS

MUD_GAS_VOC_MOLAR VOC molar PCT Value of degassed mud
at gas wells Unitless BASIN_FACTORS

MUD_GAS_CO2_MOLAR Carbon dioxide molar PCT Value of
degassed mud at gas wells Unitless BASIN_FACTORS

MUD_GAS_CH4_MOLAR Methane molar PCT Value of degassed
mud at gas wells Unitless BASIN_FACTORS

MUD_GAS_H2S_MOLAR Hydrogen sulfide molar PCT Value of
degassed mud at gas wells Unitless BASIN_FACTORS

MUD_GAS_VOC_MW Molecular weight of VOC in the
degassed mud at gas wells G/MOL BASIN_FACTORS

MUD_OIL_VOC_MOLAR VOC molar PCT Value of degassed mud

at oil wells Unitless BASIN_FACTORS

MUD_OIL_CO2_MOLAR Carbon dioxide molar PCT Value of
degassed mud at oil wells Unitless BASIN_FACTORSDecember 2012



### 88

FIELD FIELD DESCRIPTION Units WORKSHEET TAB
MUD_OIL_CH4_MOLAR Methane molar PCT Value of degassed

mud at oil wells Unitless BASIN_FACTORS

MUD_OIL_H2S_MOLAR Hydrogen sulfide molar PCT Value o f
degassed mud at oil wells Unitless BASIN_FACTORS

MUD_OIL_VOC_MW Molecular weight of VOC in the
degassed mud at oil wells G/MOL BASIN_FACTORS

MUD_OIL_MOL_PCT_BENZ Benzene molar PCT Value of dega ssed

mud at oil wells Unitless BASIN_FACTORS

MUD_OIL_MOL_PCT_ETHYLBENZ Ethylbenzene molar PCT Val ue of
degassed mud at oil wells Unitless BASIN_FACTORS

MUD_OIL_MOL_PCT_TOLUENE Toluene molar PCT Value of d egassed

mud at oil wells Unitless BASIN_FACTORS

MUD_OIL_MOL_PCT_XYLENE Xylene molar PCT Value of degassed

mud at oil wells Unitless BASIN_FACTORS

MUD_OIL_MOL_PCT_METHANE Methane molar PCT Value of deg assed

mud at oil wells Unitless BASIN_FACTORS

MUD_OIL_MOL_PCT_VOC VOC molar PCT Value of degassed mud

at oil wells Unitless BASIN_FACTORS

MUD_GAS_MOL_PCT_BENZ Benzene molar PCT Value of dega ssed
mud at gas wells Unitless BASIN_FACTORS

MUD_GAS_MOL_PCT_ETHYLBENZ Ethylbenzene molar PCT Val ue of
degassed mud at gas wells Unitless BASIN_FACTORS

MUD_GAS_MOL_PCT_TOLUENE Toluene molar PCT Value of d egassed
mud at gas wells Unitless BASIN_FACTORS

MUD_GAS_MOL_PCT_XYLENE Xylene molar PCT Value of deg assed
mud at gas wells Unitless BASIN_FACTORS

MUD_GAS_MOL_PCT_METHANE Methane molar PCT Value of degassed
mud at gas wells Unitless BASIN_FACTORS

MUD_GAS_MOL_PCT_VOC VOC molar PCT Value of degassed mud
at gas wells Unitless BASIN_FACTORS



### 6.2.16 Crude Oil Tanks

Calculation Sheet: CRUDE_OIL_TANKS_2310010200

Crude oil tank emissions are generated by working a nd breathing processes. The methodology for estimating oil tank venting emissions is shown in Equations 54-55. This methodology is based on a combined working and breathing losses VO C emissions factor on a per unit throughput basis (mass emissions per barrel of oil)

.December 2012



### 89

Equation 54) 

# > @

efficiency captured VOC tanks oil

oil VOC ks oilt 

## C C F EF P E u u

 u u 1 2000 , ,

, tan

,



### where:

E oil,tanks,VOC



### is the county-wide annual VOC venting losses from oil tanks [tons-VOC/yr]

EF oil,tank,VOC 

### is the VOC emissions factor for total losses from oil tanks [lb-VOC/bbl]

C capture 

### is the capture efficiency of the flare

C efficiency 

### is the control efficiency of the flare

F is the fraction of oil tanks with flares

P oil 

### is the county-wide oil production [bbl/yr] 2000 is the unit conversion factor lb/ton

The methodology for estimating crude oil tank losse s from other pollutants i in the working/breathing gas is shown below

Equation 55) ܧ ௟௜௢

, ௧௔௡௞௦

, ௜ 

### = ܧ ௟௜௢

, ௧௔௡௞௦

, ௏ை஼ 

### × ௪௘௜௚௛௧ ௙௥௔௖௧௜௢௡ ೔ ௪௘௜௚௛௧ ௙௥௔௖௧௜௢௡ ೇೀ಴



### where:

E oil,tanks,i 

### is the county-wide annual venting losses of pollut ant i from oil tanks [tons/yr]

E oil,tanks,VOC



### is the county-wide annual VOC venting losses from oil tanks [tons-VOC/yr] weight fraction is the mass-based concentration of pollutant i and VOC in the working/breathing gas

The methodology for estimating condensate tank comb ined losses from other pollutants i in the flashing gas is shown below

Equation 56) ܧ ௡௢௖ௗ௘௡௦௔௧௘

, ௧௔௡௞௦

, ௜ 

### = ܧ ௡௢௖ௗ௘௡௦௔௧௘

, ௧௔௡௞௦

, ௏ை஼ 

### × ௪௘௜௚௛௧ ௙௥௔௖௧௜௢௡ ೔ ௪௘௜௚௛௧ ௙௥௔௖௧௜௢௡ ೇೀ಴



### where:

E condensate,tanks,i



### is the emissions of pollutant i per liquid unit t hroughput from condensate tanks [tons/bbl]

E condensate,tanks,VOC



### is the VOC emissions per liquid unit throughput fr om condensate tanks [tons/bbl] weight fraction is the mass-based concentration of pollutant i and VOC in the flashing gas

Flaring emissions from oil tank controls

This source category includes any flaring emissions associated with controls applied to crude oil tanks. The methodology for estimating emissions fro m flaring of oil tank gas losses is described

below:December 2012



### 90

Equation 57)



### 2000 1000 , , , , 

###  ̧ 1 ·  ̈ © § u
u u u u u HV EF C C F Q P E i efficiency captured flash tanks oil countywide i tank flare



### where:

E flare,tank 

### is the county-wide emissions from crude oil tank f laring [ton/yr]

Q oil,tank,flash 

### is the volume of gas flared per unit of oil through put [MCF/bbl]

C capture 

### is the capture efficiency of the flare

C efficiency 

### is the control efficiency of the flare

F is the fraction of oil tanks with flares

EF i 

### is the flaring emissions factor for pollutant i [lb/MMBtu]

HV is the local heating value of the gas [BTU/SCF]

P countywide 

### is the annual production of oil for a particular co unty [bbl/yr] 1000 is the unit conversion factor MCF/MMCF 2000 is the unit conversion factor lb/ton

The methodology for estimating SO 2 

### emissions from flaring of oil tank losses is shown below:

Equation 58)



### 907185 2

10 5.3 2 2 5 , ,

, , 

### u u  ̧  ̧  ̧  ̧

1 ·

 ̈  ̈  ̈  ̈

© §

u u u  ̧ 1 ·  ̈ © § u

u u u u

 S H

gas countywide

efficiency captured flash tanks oil

SO tank flare 

### f

T MW R P

C C F Q P E

where:

2

, , SO tank flare 

### E 

### is the county-wide SO 2 

### emissions from flaring controls in oil tanks [ton/ yr]

P is atmospheric pressure [1 atm]

R is the universal gas constant [0.082 L-atm/mol-K]

MW gas 

### is the molecular weight of the gas [g/mol]

T is the atmospheric temperature [298 K]

S H 

### f

2 

### is the mass fraction of H 2 

### S in the gas

Q oil,tank,flash 

### is the volume of gas vented per unit of oil through put [MCF/bbl]

C capture 

### is the capture efficiency of the flare

C efficiency 

### is the control efficiency of the flare

F is the fraction of crude oil tanks with flares

P countywide 

### is the annual throughput of oil production for a pa rticular county [bbl/yr]

3.5x10 -5 

### is the unit conversion factor MCF/L 907185 is the unit conversion factor g/tonDecember 2012



### 91

Extrapolation to county-level emissions

Equations 54-58 provide county-wide estimates direc tly using by-county oil production as a surrogate. The total county-wide emissions from cru de oil tanks are the sum of flaring and crude tank working and breathing emissions (by-poll utant).

Source category data fields within the tool

FIELD FIELD DESCRIPTION Units WORKSHEET TAB
OIL_TANK_FRAC_TO_TANKS Fraction of oil directed to tanks Unitless BASIN_FACTORS

OIL_TANK_FLARE_FRAC Fraction of oil tanks with a fl are Unitless BASIN_FACTORS

OIL_TANK_AVG_FLASH_LOSSES Flashing emission factor VOC lost per
barrel (BBL) of crude oil throughput LB VOCS/BBL BASIN_FACTORS

OIL_TANK_FLARE_CAPT_EFF Capture Efficiency of the f lare Unitless BASIN_FACTORS

OIL_TANK_FLARE_CONT_EFF Control Efficiency of the f lare Unitless BASIN_FACTORS

OIL_TANK_GAS_VENTING_RATE Volume of flash gas vente d per BBL of
crude oil throughput MCF/BBL BASIN_FACTORS

OIL_TANK_LOCAL_HV Heating value of the flared gas at the

crude oil tank BTU/SCF BASIN_FACTORS

OIL_TANK_FRACT_H2S Fraction of hydrogen sulfide in the flared
gas at the crude oil tank Unitless BASIN_FACTORS

OIL_TANK_FRACT_VOC Fraction of VOC in the flared ga s at the

crude oil tank Unitless BASIN_FACTORS

OIL_TANK_MW_GAS Molecular weight of the flash gas be ing
flared at the crude oil storage tank G/MOL BASIN_FACTORS

OIL_TANK_BENZ_VOC Benzene fraction of VOC being emi tted
from crude oil storage tanks Unitless BASIN_FACTORS

OIL_TANK_ETHYLBENZ_VOC Ethylbenzene fraction of VOC being
emitted from crude oil storage tanks Unitless BASIN_FACTORS

OIL_TANK_TOLUENE_VOC Toluene fraction of VOC being emitted
from crude oil storage tanks Unitless BASIN_FACTORS

OIL_TANK_XYLENE_VOC Xylene fraction of VOC being emitted
from crude oil storage tanks Unitless BASIN_FACTORS

OIL_TANK_CH4_VOC Methane ratio to VOC being emitted
from crude oil storage tanks Unitless BASIN_FACTORS

OIL_TANK_H2S_VOC Hydrogen sulfide ratio to VOC bein g emitted from crude oil storage tanks Unitless BASIN_FACTORS



### 6.2.17 Produced water tanks

Calculation Sheets: PROD_WATER_2310000550

Water tank emissions are generated by working and b reathing processes. Because information on oil and gas field handling of produced water is limited, emissions from this source were assumed uncontrolled. The methodology for estimatin g water tank emissions is shown belowDecember 2012



### 92

separately for gas wells and oil wells as water pro duction and gas compositions for each welltype will differ:

Gas well water tanks:

Equation 59) gas water i tanks water

i gaswells water 

## S

EF E

, , ,

, , 

## 2000 u

where:

E water,tanks, i



### is the county-wide annual emissions from water tan ks located at gas wells [tons/yr]

EF water,gas wells,i



### is the emissions factor for pollutant i from worki ng/breathing losses from water tanks in gas well sites [lb/bbl]

S water,gas 

### is the county-wide annual production of water [bbl /yr] from gas wells 2000 is the unit conversion factor lbs/ton

Oil well water tanks:

Equation 60) oil water i RPwells water i LPwells water

i oilwells water 

## S F EF F EF E

, , , , ,

, , 

## 2000 ) 1(

u  u  u

where:

E water,oil wells,i



### is the county-wide annual emissions from water tan ks located at oil wells [tons/yr]

EF water,LP,i 

### is the emissions factor for pollutant i from worki ng/breathing losses from water tanks at low pressure oil wells (i.e. wells with ar tificial lifts) [lb/bbl]

EF water,LP,i 

### is the emissions factor for pollutant i from worki ng/breathing losses from water tanks at regular pressure oil well sites [lb/bbl]

F is the fraction of water production from oil wells with artificial lifts

S water,oil 

### is the county-wide annual production of water [bbl /yr] from oil wells 2000 is the unit conversion factor lbs/ton

To estimate emissions from other pollutants in the losses from water tanks, the following equation may be used:

Equation 61)

4 4 , , , 4 CH i

CH i
wells water i wells water 

## M M

MW MW E E

CH 

## u

u

where:

E water,wells,i 

### is the water tank county-wide venting losses of po llutant i from water tanks at particular well type (oil or gas) [ton/yr]

EF water,wells,CH4 

### is the water tank emissions for methane for a parti cular well type [ton CH4/yr]

MW i 

### is the molecular weight of pollutant i [lb/lb-mol]December 2012



### 93

MW CH4 

### is the molecular weight of methane [lb/lb-mol]

M CH4 

### is the mole percent of methane in the water tanks gas (local produced gas) [%]

M i 

### is the mole percent of pollutant in the water tank s gas (local produced gas) [%]

Extrapolation to county-level emissions

County-wide emissions from produced water tanks are estimated directly from equations 59 through 61. The sum of oil wells and gas wells wate r tank emissions yield total county-wide

emissions from water tanks.

Source category data fields within the tool

FIELD FIELD DESCRIPTION Units WORKSHEET TAB
PROD_WATER_FRACT_TANK Fraction of produced water se nt to

tanks Unitless BASIN_FACTORS

PROD_WATER_AVG_LOSS_GAS WELLS Average Methane losse s from gas

wells LB/BBL BASIN_FACTORS

PROD_WATER_WELLS_ART_LIFT_OIL WELLS Fraction of low pressure oil wells,

i.e. fraction of wells with artificial

lifts Unitless BASIN_FACTORS

PROD_WATER_AVG_LOSS_LP_OIL WELLS Average Methane lo sses from Low

Pressure oil wells LB/BBL BASIN_FACTORS

PROD_WATER_AVG_LOSS_REG_OIL WELLS Average Methane l osses from
Regular Pressure oil wells LB/BBL BASIN_FACTORS

PROD_WATER_GASWELL_VOC_MOLAR VOC molar PCT Value of produced
water at gas wells Unitless BASIN_FACTORS

PROD_WATER_GASWELL_CO2_MOLAR Carbon dioxide molar PC T Value of
produced water at gas wells Unitless BASIN_FACTORS

PROD_WATER_GASWELL_CH4_MOLAR Methane molar PCT Value of
produced water at gas wells Unitless BASIN_FACTORS

PROD_WATER_GASWELL_H2S_MOLAR Hydrogen sulfide molar PCT Value
of produced water at gas wells Unitless BASIN_FACTORS

PROD_WATER_GASWELL_VOC_MW Molecular weight of VOC in the
produced water at gas wells G/MOL BASIN_FACTORS

PROD_WATER_OILWELL_VOC_MOLAR VOC molar PCT Value of produced

water at oil wells Unitless BASIN_FACTORS

PROD_WATER_OILWELL_CO2_MOLAR Carbon dioxide molar PC T Value of
produced water at oil wells Unitless BASIN_FACTORS

PROD_WATER_OILWELL_CH4_MOLAR Methane molar PCT Value of
produced water at oil wells Unitless BASIN_FACTORS

PROD_WATER_OILWELL_H2S_MOLAR Hydrogen sulfide molar PCT Value
of produced water at oil wells Unitless BASIN_FACTORS

PROD_WATER_OILWELL_VOC_MW Molecular weight of VOC in the
produced water at oil wells G/MOL BASIN_FACTORS

PROD_WATER_OIL_MOL_PCT_BENZ Benzene molar PCT Value of
produced water at oil wells Unitless BASIN_FACTORSDecember 2012



### 94

FIELD FIELD DESCRIPTION Units WORKSHEET TAB

PROD_WATER_OIL_MOL_PCT_ETHYLBENZ Ethylbenzene molar PCT Value of
produced water at oil wells Unitless BASIN_FACTORS

PROD_WATER_OIL_MOL_PCT_TOLUENE Toluene molar PCT Val ue of
produced water at oil wells Unitless BASIN_FACTORS

PROD_WATER_OIL_MOL_PCT_XYLENE Xylene molar PCT Value of
produced water at oil wells Unitless BASIN_FACTORS

PROD_WATER_OIL_MOL_PCT_METHANE Methane molar PCT Value of
produced water at oil wells Unitless BASIN_FACTORS

PROD_WATER_OIL_MOL_PCT_VOC VOC molar PCT Value of pr oduced

water at oil wells Unitless BASIN_FACTORS

PROD_WATER_GAS_MOL_PCT_BENZ Benzene molar PCT Value of
produced water at gas wells Unitless BASIN_FACTORS

PROD_WATER_GAS_MOL_PCT_ETHYLBENZ Ethylbenzene molar PCT Value of
produced water at gas wells Unitless BASIN_FACTORS

PROD_WATER_GAS_MOL_PCT_TOLUENE Toluene molar PCT Val ue of
produced water at gas wells Unitless BASIN_FACTORS

PROD_WATER_GAS_MOL_PCT_XYLENE Xylene molar PCT Value of
produced water at gas wells Unitless BASIN_FACTORS

PROD_WATER_GAS_MOL_PCT_METHANE Methane molar PCT Value of
produced water at gas wells Unitless BASIN_FACTORS

PROD_WATER_GAS_MOL_PCT_VOC VOC molar PCT Value of pr oduced
water at gas wells Unitless BASIN_FACTORS



### 6.2.18 Casinghead gas venting

Calculation sheets: CASING_HEAD_GAS_2310011000

This section refers to the practice of venting asso ciated gas from oil wells which sometimes takes place when the well is not connected to a gas sales pipeline or when amount of gas produced by the well is so limited that is not prof itable for capture. The calculation methodology for estimating basin-wide emissions fro m casing gas vented is shown below in
Equation 62:

Equation 62) efficiency captured flare i

gas oil

gas g ca

i gas g ca 

### C C F f

T MW R S Q P E u u

 u u  ̧  ̧  ̧  ̧

1 ·

 ̈  ̈  ̈  ̈

© §

u

u u  ̧ 1 ·  ̈ © § u u

 

### 1

907185 10 5.3 5 , sin

, , sin



### where:

E casing,gas,i 

### is the county-wide emissions of pollutant i from casing gas venting [ton/bbl]

P is atmospheric pressure [1 atm]

Q casing,gas,i 

### is the venting rate of casing gas per unit of oil production [MCF/bbl]December 2012



### 95

R is the universal gas constant [0.082 L-atm/mol-K]

MW gas 

### is the molecular weight of the gas [g/mol]

T is the atmospheric temperature [298 K] f i 

### is the mass fraction of pollutant i in the casing gas

S oil 

### is the annual county-wide production of oil [bbl/yr ]

F flare 

### is the fraction of casing gas vent controlled with flares

C capture 

### is the capture efficiency of the flare

C efficiency 

### is the control efficiency of the flare

3.5x10 -5 

### is the unit conversion factor MCF/L 907185 is the unit conversion factor g/ton

Flaring emissions from casing gas controls

Emissions from flaring controls applied to casing h ead gas are included in this source category. The methodology for estimating emissions from flari ng of casing gas is described below:

Equation 63) 2000 1000 , sin

, , sin 

###  ̧  ̧ 1 ·  ̈  ̈ © §

u u u u u u

oil efficiency captured gas g ca i

i gas g ca 

### S HV C C F Q EF E

where:

E flare,casing,gas 

### is the county-wide flaring emissions of pollutant i from vented casing gas [ton/yr]

EF i 

### is the flaring emissions factor for pollutant i [lb/MMBtu]

Q casing,gas 

### is the volume of casing gas vented per barrel of oi l produced [MCF/bbl]

HV is the local heating value of the gas [BTU/SCF]

S oil 

### is the annual county-wide production of oil [bbl/yr ]

F is the fraction of casing gas vent controlled with flares

C capture 

### is the capture efficiency of the flare

C efficiency 

### is the control efficiency of the flare 2000 is the unit conversion factor lbs/ton

The methodology for estimating SO 2 

### emissions from flaring of casing head gas is shown below:

Equation 64)

efficiency captured flare SO

gas oil

gas g ca
SO flare g ca 

### C C F f

T MW R S Q P E u u u u u  ̧  ̧  ̧  ̧

1 ·

 ̈  ̈  ̈  ̈

© §

u

u u  ̧ 1 ·  ̈ © § u u

 

### 907185

2

10 5.3 2

2 5 , sin

, , sin



### where:

2 , , sin SO flare g ca 

### E 

### is the county-wide SO 2 

### emissions from flaring of casing gas [ton/yr]

P is atmospheric pressure [1 atm]December 2012



### 96

Q casing,gas 

### is vented volume of casing gas per barrel of oil [M CF/bbl]

S oil 

### is the annual county-wide production of oil [bbl/yr ]

R is the universal gas constant [0.082 L-atm/mol-K]

MW gas 

### is the molecular weight of the casing gas [g/mol]

T is the atmospheric temperature [298 K]

S H 

### f

2 

### is the mass fraction of H 2 

### S in the casing gas

F is the fraction of casing gas vents controlled by flare

C capture 

### is the capture efficiency of the flare

C efficiency 

### is the control efficiency of the flare

3.5x10 -5 

### is the unit conversion factor MCF/L 907185 is the unit conversion factor g/ton

Extrapolation to county-level emissions

County-wide emissions from casing gas venting and c asing gas flaring are estimated directly from Equations 62-64. The sum of venting and flarin g emissions by pollutant yield the total county-wide emissions from casing head gas that is not captured for sale.

Source category data fields within the tool

FIELD FIELD DESCRIPTION Units WORKSHEET TAB
CASING_GAS_VENTING_RATE Venting rate of casing gas per unit of oil
production throughput MCF/BBL BASIN_FACTORS

CASING_GAS_FRACT_VENTS_CONT Fraction of casing gas vent controlled

with flares Unitless BASIN_FACTORS

CASING_GAS_FLARING_CONT_EFF Control Efficiency of t he flare Unitless BASIN_FACTORS

CASING_GAS_FLARING_CAPTURE_EFF Capture Efficiency of the flare Unitless BASIN_FACTORS

CASING_GAS_WT_FRACT_VOC Fraction of VOC in the vent ed casing gas Unitless BASIN_FACTORS

CASING_GAS_WT_FRACT_H2S Fraction of Hydrogen sulfide in the
vented casing gas Unitless BASIN_FACTORS

CASING_GAS_WT_FRACT_CO Fraction of CO in the vented casing gas Unitless BASIN_FACTORS

CASING_GAS_WT_FRACT_CH4 Fraction of Methane in the vented

casing gas Unitless BASIN_FACTORS

CASING_GAS_WT_FRACT_BENZ Fraction of Benzene in the vented casing

gas Unitless BASIN_FACTORS

CASING_GAS_WT_FRACT_ETHYLBENZ Fraction of Ethylbenz ene in the vented

casing gas Unitless BASIN_FACTORS

CASING_GAS_WT_FRACT_TOLUENE Fraction of Toluene in the vented casing

gas Unitless BASIN_FACTORS

CASING_GAS_WT_FRACT_XYLENE Fraction of Xylene in th e vented casing

gas Unitless BASIN_FACTORS

CASING_GAS_LHV Heating value of the vented casing gas BTU/SCF BASIN_FACTORS

CASING_GAS_MW Molecular weight of the vented casing

gas G/MOL BASIN_FACTORSDecember 2012



### 97



## 6.3 Output Emissions Summary

The nonpoint emission estimates from each worksheet is linked to a “compiled_emissions” worksheet, which contains the entire emissions inve ntory for the state. At this point, the user can simply upload this tab into a database program for further data analysis. The information in the “compiled_emissions” worksheet is then fed to s ummary Pivot tables, which provides easyto-use summaries of source category emissions, geog raphic emissions, and activity data. These

worksheet tabs are:

x EMISSIONS_SUMMARY_GEOGRAPHIC

x EMISSIONS_SUMMARY_SOURCE

x ACTIVITY_SUMMARY_GEOGRAPHIC

The information in the “compiled_emissions” workshe et are also fed into four worksheet tabs relating to the EPA’s Emission Inventory System (EI S) data submittal for nonpoint sources. The EIS staging tables for nonpoint sources can be foun d in “Nonpoint Inventory – April 2012” at http://www.epa.gov/ttn/chief/eidocs/training.html#e is.



## 6.4 Formatting tool for NEI submission

Within each workbook, selected information in the “ compiled_emissions” worksheet are also fed into four worksheet tabs relating to the EPA’s Emission Inventory System (EIS) data submittal for nonpoint sources. The EIS staging tab les for nonpoint sources can be found in “Nonpoint Inventory – April 2012” at http://www.epa.gov/ttn/chief/eidocs/training.html#e is

. Although there are 13 tables relating to the nonpoi nt staging tables, EPA requires that the following four data tables need to be submitted:

x Emissions

x EmissionProcess

x ReportingPeriod

x Location

The User can simply import the information from the se four tabs into their emission inventory database program to generate the XML files needed f or submittal. As a way to check the format of these EIS tables, a sample output XML file from one of the states’ tools was submitted to the EIS QA environment, and passed through the system c hecks without any issues.December 2012



### 98



## 7.0 RESULTS

7.1 2011 Oil and Gas Area Source Emissions

Emissions estimates were compiled from each State’s tool to arrive at the basin-wide inventories for the oil and gas regions within the CenSARA domain. Emissions were collected from the ‘compiled_emissions’ tab in each of the to ols and combined in a Microsoft Access database to aggregate emissions from each State and allocate them in equivalent basin and source category bins. Emissions inventories develop ed in this work are highly detailed in their geographical specificity (detail by basin, state an d county), in the array of pollutants included (16 total) and the number of source categories anal yzed (18 area sources, 34 SCCs). Hence, for the purpose of summarizing results in this report, only key pollutants relevant to air quality issues of interest to CenSARA will be highlighted. For more detailed emissions, the User can manipulate the pivot table summaries within each to ol to display emissions in the desired
groupings.

Basin-wide emissions by source are shown in Table 7 -1 for selected pollutants including the major criteria pollutants (NOx, VOC, CO, PM 10 

### , PM 2.5 

### , SO 2 

### ), hydrogen sulfide (H 2 

### S)

, 

### total HAPs (a combination of benzene, ethylbenzene, toluene, xyle ne, formaldehyde and n-hexane) and methane (CH 4 

### ).

Following Table 7-1, the distribution of total CenS ARA domain emissions allocated by State, and by each basin within a CenSARA state is shown in Ta ble 7-2.

As stated earlier in this report, the following dat a should be considered preliminary. As the states complete their QA/QC and take into considera tion additional information (ex: applicable control measures), there will likely be changes. E ach state should be contacted regarding what it has been ultimately reported to the NEI.December 201299Table 7-1. Basin-wide emissions by area source category for 2011 in the CenSARA domain.Basin/Source Category2011 Emissions (Tons per year)NOxCOVOCSO2PM10PM2.5H2SHAPsCH4Anadarko Basin108,951.8133,644.6273,065.589.13,767.93,761.548.94,087.6708,482.8Artificial Lift Engines9,028.413,960.2117.72.377.277.2-90.9914.8Blowdowns--38,738.4 10.7 ---77.0 99,343.0Casinghead Gas Venting--738.8 0.0 ----2,964.2Condensate Tanks196.8 1,040.5 10,201.2 ----306.3 6,664.9Crude Oil Tanks0.0 0.2 13,377.2 ----25.9 79.4Dehydrators0.0 0.0 1,545.3 -0.00.0 -587.2 2,024.3Drill Rigs4,899.31,116.7308.28.5191.1186.1-38.45.0Fugitives--17,828.3 ---4.0 26.3 50,765.0Gas-Actuated Pumps--8,735.9 ---2.2 16.0 23,384.4Heaters20,686.517,376.61,137.80.01,572.21,572.2-159.3475.8Hydraulic Fracturing1,126.1 254.5 71.1 1.9 43.842.5 -8.9 1.2Lateral/Gathering LineCompressors22,250.0 31,625.1 876.4 18.8 592.5592.5 -730.9 10,400.2Loading Emissions--1,063.0---0.014.0149.4Mud Degassing--8,419.7 ---1.3 8.8 27,383.9Pneumatic Devices--166,568.8 ---41.2 294.8 453,681.8Produced Water--772.3 ---0.2 1.5 2,006.1Well Completions96.1 507.8 128.8 4.5 ---54.9 71.5Wellhead Compressor Engines50,668.6 67,763.0 2,436.7 42.4 1,291.01,291.0 -1,646.6 28,168.1Arkoma Basin15,615.512,461.816,273.717.2428.6425.33.5340.8294,226.3Artificial Lift Engines866.4 1,339.7 11.3 0.2 7.47.4 -8.7 87.8Blowdowns--3,911.60.3----99,372.0December 2012100Basin/Source Category2011 Emissions (Tons per year)NOxCOVOCSO2PM10PM2.5H2SHAPsCH4Casinghead Gas Venting---------Condensate Tanks1.0 5.2 38.2 ----0.6 56.3Crude Oil Tanks--1,357.6 5.6 ---63.9 180.6Dehydrators0.00.014.2-0.00.0-11.614.6Drill Rigs1,221.0 286.7 74.9 2.3 48.146.8 -9.3 1.2Fugitives--1,368.4 ---1.1 -13,460.9Gas-Actuated Pumps--707.7---0.6-5,724.0Heaters2,473.3 2,077.6 136.0 0.0 188.0188.0 -19.0 56.9Hydraulic Fracturing1,688.9 381.7 106.6 2.9 65.763.7 -13.3 1.7Lateral/Gathering LineCompressors3,003.52,403.9300.31.837.737.7-71.13,172.0Loading Emissions--7.5 ---0.0 0.0 0.1Mud Degassing--341.4 ---0.1 -6,162.2Pneumatic Devices--7,043.5 ---1.6 -158,096.8Produced Water---------Well Completions1.2 6.4 315.7 0.5 ---0.7 2,158.5Wellhead Compressor Engines6,360.2 5,960.7 538.9 3.7 81.781.7 -142.4 5,680.7Bend Arch-Fort Worth Basin144,032.1189,210.9147,646.41,667.32,468.92,464.81,1063,099.4458,542.4Artificial Lift Engines8,596.6 13,292.6 112.1 2.2 73.573.5 -86.6 871.0Blowdowns--12,307.2 1.0 ---32.5 60,509.5Casinghead Gas Venting0.1 0.4 1,042.2 1,062.0 ---5.0 1,457.1Condensate Tanks19.1 101.1 12,544.2 ----135.0 5,045.4Crude Oil Tanks1.2 6.6 13,093.3 487.4 ---317.1 1,832.8Dehydrators0.0 0.0 81.6 -0.00.0 -26.9 427.6Drill Rigs3,539.4859.3213.36.8140.9137.0-26.53.5December 2012101Basin/Source Category2011 Emissions (Tons per year)NOxCOVOCSO2PM10PM2.5H2SHAPsCH4Fugitives--14,693.9---268.176.837,108.9Gas-Actuated Pumps--5,114.4 ---68.8 23.0 12,994.7Heaters10,873.8 9,134.0 598.1 0.1 826.4826.4 -83.7 250.1Hydraulic Fracturing199.245.012.60.37.87.5-1.60.2Lateral/Gathering LineCompressors8,631.4 12,391.0 246.4 3.1 91.691.6 -120.7 2,397.8Loading Emissions--255.7 ---0.0 3.1 7.4Mud Degassing--2,735.0---23.910.08,791.6Pneumatic Devices--74,054.9 ---729.2 286.8 259,451.4Produced Water--4,407.0 ---16.0 13.2 17,832.4Well Completions13.973.31,853.657.3---14.96,151.0Wellhead Compressor Engines112,157.3 153,307.6 4,281.0 47.2 1,328.71,328.7 -1,836.0 43,410.0Cambridge Arch-Central KansasUplift9,339.911,728.839,793.72.4282.8282.50.0209.786,424.4Artificial Lift Engines1,413.7 2,186.0 18.4 0.4 12.112.1 -14.2 143.2Blowdowns--542.9 ----0.2 9,202.2Casinghead Gas Venting0.1 0.7 713.2 ----0.1 1,364.3Condensate Tanks--8,418.8 ----40.5 1,929.2Crude Oil Tanks--3,039.6 ----73.4 425.4Dehydrators0.0 0.0 0.8 -0.00.0 -0.7 0.9Drill Rigs246.6 66.3 13.4 0.6 10.29.9 -1.7 0.2Fugitives--5,612.6 ----0.0 12,739.3Gas-Actuated Pumps--1,418.7 ----0.0 3,412.7Heaters2,868.6 2,409.6 157.8 -218.0218.0 -22.1 66.0Hydraulic Fracturing---------December 2012102Basin/Source Category2011 Emissions (Tons per year)NOxCOVOCSO2PM10PM2.5H2SHAPsCH4Lateral/Gathering LineCompressors917.61,272.432.80.38.48.4-12.0319.5Loading Emissions--69.6 ---0.0 0.9 0.5Mud Degassing--547.1 ----0.0 1,141.8Pneumatic Devices--18,732.4----0.352,516.8Produced Water--112.8 ----0.0 1,799.0Well Completions--279.8 ----0.0 619.1Wellhead Compressor Engines3,893.35,793.882.91.134.134.1-43.5744.3Cherokee Platform36,316.448,490.073,950.7567.4791.4791.1620.1901.9240,037.0Artificial Lift Engines10,550.7 16,314.0 137.6 2.7 90.290.2 -106.2 1,069.0Blowdowns--7,665.40.6---20.237,687.6Casinghead Gas Venting0.0 0.1 354.3 361.1 ---1.7 495.4Condensate Tanks3.9 20.4 2,528.4 ----27.2 1,016.9Crude Oil Tanks0.4 2.2 4,451.6 165.7 ---107.8 623.1Dehydrators0.0 0.0 59.2 -0.00.0 -48.5 60.9Drill Rigs171.5 53.9 9.5 0.4 7.37.1 -1.1 0.1Fugitives--8,216.3 ---144.8 42.2 21,427.0Gas-Actuated Pumps--2,898.4 ---37.1 12.8 7,650.2Heaters6,193.6 5,202.6 340.6 0.0 470.7470.7 -47.7 142.5Hydraulic Fracturing1.1 0.2 0.1 0.0 0.00.0 -0.0 0.0Lateral/Gathering LineCompressors5,375.9 7,717.6 153.5 1.9 57.157.1 -75.2 1,493.5Loading Emissions--55.4 ---0.0 0.7 1.6Mud Degassing--2,538.3 ---44.3 12.1 4,564.3Pneumatic Devices--43,364.8 ---393.9 163.8 156,710.8December 2012103Basin/Source Category2011 Emissions (Tons per year)NOxCOVOCSO2PM10PM2.5H2SHAPsCH4Produced Water---------Well Completions4.0 21.3 642.5 29.1 ---5.3 1,669.6Wellhead Compressor Engines14,015.3 19,157.5 535.0 5.9 166.0166.0 -229.4 5,424.6Denver Basin1,547.22,203.17,693.40.420.820.80.252.411,984.2Artificial Lift Engines5.7 8.8 0.1 0.0 0.00.0 -0.1 0.6Blowdowns--161.8 ----0.0 2,741.9Casinghead Gas Venting0.00.016.1----0.030.7Condensate Tanks--6,735.8 ----32.4 1,543.6Crude Oil Tanks--68.5 ----1.7 9.6Dehydrators0.00.00.1-0.00.0-0.10.1Drill Rigs3.5 0.9 0.2 0.0 0.10.1 -0.0 0.0Fugitives--61.8 ----0.0 714.7Gas-Actuated Pumps--93.4 ---0.2 0.0 245.1Heaters104.5 87.8 5.7 0.0 7.97.9 -0.8 2.4Hydraulic Fracturing---------Lateral/Gathering LineCompressors273.4379.19.80.12.52.5-3.695.2Loading Emissions--54.3 ---0.0 0.7 0.4Mud Degassing--4.2 -----8.0Pneumatic Devices--401.8 ----0.1 5,737.6Produced Water--45.8 -----614.4Well Completions--9.5 -----18.1Wellhead Compressor Engines1,160.1 1,726.3 24.7 0.3 10.210.2 -13.0 221.8East Texas Basin128,840.1171,678.3100,631.5944.41,975.31,972.9439.83,417.4364,708.0Artificial Lift Engines3,576.35,529.946.60.930.630.6-36.0362.4December 2012104Basin/Source Category2011 Emissions (Tons per year)NOxCOVOCSO2PM10PM2.5H2SHAPsCH4Blowdowns--11,445.50.9---30.256,273.2Casinghead Gas Venting0.0 0.2 591.8 603.0 ---2.8 827.5Condensate Tanks13.5 71.4 8,858.4 ----95.3 3,562.9Crude Oil Tanks0.73.77,435.2276.8---180.01,040.8Dehydrators0.0 0.0 1,491.3 -0.00.0 -879.9 417.6Drill Rigs2,023.6 517.8 120.1 4.0 81.679.3 -14.8 1.9Fugitives--7,691.6---107.535.323,747.5Gas-Actuated Pumps--2,923.5 ---27.6 11.5 9,254.1Heaters6,415.7 5,389.2 352.9 0.0 487.6487.6 -49.4 147.6Hydraulic Fracturing60.113.63.80.12.32.3-0.50.1Lateral/Gathering LineCompressors8,027.1 11,523.5 229.2 2.9 85.285.2 -112.3 2,230.0Loading Emissions--405.4 ---0.0 4.6 12.1Mud Degassing--916.9 ---3.4 2.8 3,700.4Pneumatic Devices--51,252.8 ---293.6 171.8 210,096.9Produced Water--2,237.4 ---7.7 6.7 9,119.9Well Completions4.0 21.1 479.4 10.0 ---3.8 1,834.0Wellhead Compressor Engines108,719.1 148,607.9 4,149.7 45.8 1,288.01,288.0 -1,779.7 42,079.2Forest City Basin4,344.96,090.18,186.21.189.289.111.558.719,014.8Artificial Lift Engines3,032.0 4,688.3 39.5 0.8 25.925.9 -30.5 307.2Blowdowns--58.2 ----0.1 298.0Casinghead Gas Venting0.0 0.0 29.9 ----0.0 66.5Condensate Tanks--142.2 ----0.7 32.6Crude Oil Tanks--180.2 ----4.4 25.2Dehydrators0.00.00.3-0.00.0-0.30.3December 2012105Basin/Source Category2011 Emissions (Tons per year)NOxCOVOCSO2PM10PM2.5H2SHAPsCH4Drill Rigs47.812.82.60.12.01.9-0.30.0Fugitives--1,493.1 ----1.7 3,413.5Gas-Actuated Pumps--395.6 ---11.5 0.5 854.2Heaters745.8626.541.00.056.756.7-5.717.2Hydraulic Fracturing---------Lateral/Gathering LineCompressors101.6 140.9 3.6 0.0 0.90.9 -1.3 35.4Loading Emissions--1.4---0.00.00.0Mud Degassing--534.8 ----1.7 1,028.1Pneumatic Devices--5,093.1 ----6.5 12,458.4Produced Water--24.1----0.092.5Well Completions--137.5 ----0.2 305.9Wellhead Compressor Engines417.7 621.5 8.9 0.1 3.73.7 -4.7 79.8Illinois Basin15.313.515.60.00.40.40.00.3372.7Artificial Lift Engines---------Blowdowns--5.1 0.0 ----130.0Casinghead Gas Venting---------Condensate Tanks---------Crude Oil Tanks---------Dehydrators0.0 0.0 0.0 -0.00.0 -0.0 0.0Drill Rigs---------Fugitives--0.7 ---0.0 -17.2Gas-Actuated Pumps--0.4 -----7.3Heaters3.1 2.6 0.2 0.0 0.20.2 -0.0 0.1Hydraulic Fracturing---------December 2012106Basin/Source Category2011 Emissions (Tons per year)NOxCOVOCSO2PM10PM2.5H2SHAPsCH4Lateral/Gathering LineCompressors3.93.10.40.00.00.0-0.14.2Loading Emissions---------Mud Degassing---------Pneumatic Devices--8.1---0.0-206.5Produced Water---------Well Completions---------Wellhead Compressor Engines8.37.80.70.00.10.1-0.27.4Louisiana-Mississippi Salt Basins39,831.949,055.740,340.8458.71,053.91,050.61,4041,726.2158,600.9Artificial Lift Engines2,880.0 4,453.3 37.6 0.7 24.624.6 -29.0 291.8Blowdowns--825.9----8.95,353.5Casinghead Gas Venting---------Condensate Tanks2.2 11.8 2,679.1 ----40.3 209.8Crude Oil Tanks--2,118.9 308.8 ---25.4 513.0Dehydrators0.0 0.0 613.7 -0.00.0 -503.3 632.2Drill Rigs3,061.7 704.9 192.1 5.3 119.7116.5 -23.9 3.1Fugitives--5,838.1 ---421.9 156.8 17,901.9Gas-Actuated Pumps--1,886.1 ---108.9 44.6 7,080.8Heaters8,349.7 7,013.8 459.2 0.1 634.6634.6 -64.3 192.0Hydraulic Fracturing70.1 15.8 4.4 0.1 2.72.6 -0.6 0.1Lateral/Gathering LineCompressors10,066.5 15,565.4 131.3 2.6 86.186.1 -101.4 1,020.0Loading Emissions--164.6 ---0.0 2.2 1.2Mud Degassing--360.5 ---23.6 9.3 1,223.1Pneumatic Devices--22,961.1 ---790.2 423.9 111,484.9December 2012107Basin/Source Category2011 Emissions (Tons per year)NOxCOVOCSO2PM10PM2.5H2SHAPsCH4Produced Water--1,453.1---59.629.46,605.2Well Completions10.1 53.6 19.9 134.3 ---6.0 30.8Wellhead Compressor Engines15,391.5 21,237.2 595.2 6.6 186.1186.1 -257.0 6,057.7Marathon Thrust Belt3,863.25,585.24,525.21.651.951.90.564.813,172.8Artificial Lift Engines2.3 3.5 0.0 0.0 0.00.0 -0.0 0.2Blowdowns--906.4 -----2,607.9Casinghead Gas Venting---------Condensate Tanks0.3 1.4 236.8 ----2.5 95.2Crude Oil Tanks0.0 0.0 2.5 0.1 ---0.1 0.3Dehydrators0.00.010.5-0.00.0-5.111.8Drill Rigs21.9 5.0 1.4 0.0 0.90.8 -0.2 0.0Fugitives--152.8 ---0.1 -440.5Gas-Actuated Pumps--28.0 ---0.1 -208.9Heaters90.9 76.4 5.0 0.0 6.96.9 -0.7 2.1Hydraulic Fracturing---------Lateral/Gathering LineCompressors232.3333.56.60.12.52.5-3.264.5Loading Emissions--5.4 ---0.0 0.1 0.2Mud Degassing--13.9 ---0.2 0.2 41.8Pneumatic Devices--3,058.3 ---0.2 -8,801.3Produced Water--9.4 ---0.0 0.1 32.2Well Completions---------Wellhead Compressor Engines3,515.6 5,165.6 88.2 1.4 41.741.7 -52.7 865.8Nemaha Uplift9,081.412,867.022,701.92.3158.1158.014.9192.343,783.4Artificial Lift Engines3,933.26,081.851.31.033.633.6-39.6398.5December 2012108Basin/Source Category2011 Emissions (Tons per year)NOxCOVOCSO2PM10PM2.5H2SHAPsCH4Blowdowns--443.3----0.92,268.4Casinghead Gas Venting0.0 0.1 103.9 ----0.1 231.1Condensate Tanks--8,578.0 ----41.3 1,965.7Crude Oil Tanks--626.7----15.187.7Dehydrators0.0 0.0 26.3 -0.00.0 -21.5 27.1Drill Rigs39.2 10.5 2.1 0.1 1.61.6 -0.3 0.0Fugitives--2,187.0----2.75,735.0Gas-Actuated Pumps--679.2 ---14.9 1.0 1,662.1Heaters1,156.9 971.8 63.6 0.0 87.987.9 -8.9 26.6Hydraulic Fracturing---------Lateral/Gathering LineCompressors773.3 1,072.3 27.6 0.3 7.17.1 -10.1 269.2Loading Emissions--78.3 ---0.0 1.0 0.6Mud Degassing--88.3 ----0.3 179.5Pneumatic Devices--9,067.3 ----13.2 28,750.1Produced Water---------Well Completions--611.2 ----0.8 1,574.0Wellhead Compressor Engines3,178.8 4,730.6 67.7 0.9 27.927.9 -35.5 607.7Ozark Uplift---------Artificial Lift Engines---------Blowdowns---------Casinghead Gas Venting---------Condensate Tanks---------Crude Oil Tanks---------Dehydrators---------December 2012109Basin/Source Category2011 Emissions (Tons per year)NOxCOVOCSO2PM10PM2.5H2SHAPsCH4Drill Rigs---------Fugitives---------Gas-Actuated Pumps---------Heaters---------Hydraulic Fracturing---------Lateral/Gathering LineCompressors---------Loading Emissions---------Mud Degassing---------Pneumatic Devices---------Produced Water---------Well Completions---------Wellhead Compressor Engines---------Palo Duro Basin5,879.27,884.96,570.0206.994.894.737.8159.717,978.0Artificial Lift Engines289.2 447.2 3.8 0.1 2.52.5 -2.9 29.3Blowdowns--530.9 0.0 ---1.4 2,610.3Casinghead Gas Venting0.0 0.1 136.8 139.4 ---0.7 191.3Condensate Tanks0.3 1.7 216.3 ----2.3 87.0Crude Oil Tanks0.2 0.9 1,719.3 64.0 ---41.6 240.7Dehydrators0.0 0.0 10.8 -0.00.0 -8.9 11.1Drill Rigs15.6 4.7 0.9 0.0 0.70.6 -0.1 0.0Fugitives--532.0 ---9.1 2.7 1,417.2Gas-Actuated Pumps--189.4 ---2.3 0.8 512.3Heaters406.0 341.0 22.3 0.0 30.930.9 -3.1 9.3Hydraulic Fracturing0.60.10.00.00.00.0-0.00.0December 2012110Basin/Source Category2011 Emissions (Tons per year)NOxCOVOCSO2PM10PM2.5H2SHAPsCH4Lateral/Gathering LineCompressors372.3534.510.60.14.04.0-5.2103.4Loading Emissions--6.9 ---0.0 0.1 0.2Mud Degassing--43.2 ---0.6 0.2 104.5Pneumatic Devices--2,894.0---24.910.810,660.2Produced Water--49.0 ---0.8 0.2 99.9Well Completions0.1 0.6 20.7 1.1 ---0.2 45.4Wellhead Compressor Engines4,794.86,554.0183.02.056.856.8-78.51,855.8Permian Basin166,428.8226,582.7386,201.58,625.63,437.33,431.63,2886,910.9626,541.9Artificial Lift Engines24,576.8 38,001.9 320.5 6.4 210.1210.1 -247.5 2,490.2Blowdowns107.8569.727,390.3----61.678,473.1Casinghead Gas Venting---------Condensate Tanks16.8 88.9 15,190.4 ----159.9 6,109.3Crude Oil Tanks107.4 567.8 180,759.1 7,904.5 ---4,425.8 25,338.2Dehydrators0.0 0.0 134.1 -0.00.0 -64.3 150.1Drill Rigs5,506.9 1,244.8 347.5 9.4 214.4208.7 -43.3 5.7Fugitives--19,903.1 ---890.9 -65,917.4Gas-Actuated Pumps--6,409.2 ---246.1 -20,833.8Heaters21,945.3 18,434.1 1,207.0 0.2 1,667.81,667.8 -169.0 504.7Hydraulic Fracturing33.3 7.5 2.1 0.1 1.31.3 -0.3 0.0Lateral/Gathering LineCompressors6,984.0 10,026.1 199.4 2.5 74.174.1 -97.7 1,940.2Loading Emissions--393.1 ---0.0 4.9 11.4Mud Degassing--3,617.0 ---158.9 -11,952.2Pneumatic Devices--124,290.1 ---1,881 -375,892.9December 2012111Basin/Source Category2011 Emissions (Tons per year)NOxCOVOCSO2PM10PM2.5H2SHAPsCH4Produced Water--3,279.4---110.3-10,508.6Well Completions53.4 282.1 71.1 661.2 ---30.5 38.9Wellhead Compressor Engines107,097.0 157,359.7 2,688.1 41.3 1,269.51,269.5 -1,606.2 26,375.2Salina Basin82.285.6610.30.04.14.10.82.2994.6Artificial Lift Engines26.4 40.9 0.3 0.0 0.20.2 -0.3 2.7Blowdowns--0.2 ----0.0 3.5Casinghead Gas Venting0.00.011.2----0.021.3Condensate Tanks--73.4 ----0.4 16.8Crude Oil Tanks--47.6 ----1.1 6.7Dehydrators0.00.00.0-0.00.0-0.00.0Drill Rigs5.8 1.6 0.3 0.0 0.20.2 -0.0 0.0Fugitives--103.2 ----0.0 198.2Gas-Actuated Pumps--16.0 ---0.8 0.0 49.7Heaters48.2 40.5 2.6 0.0 3.73.7 -0.4 1.1Hydraulic Fracturing---------Lateral/Gathering LineCompressors0.40.50.00.00.00.0-0.00.1Loading Emissions--0.6 ---0.0 0.0 0.0Mud Degassing--15.3 -----29.2Pneumatic Devices--332.1 ----0.0 641.8Produced Water--0.7 -----10.2Well Completions--6.8 -----12.9Wellhead Compressor Engines1.5 2.2 0.0 0.0 0.00.0 -0.0 0.3Sedgwick Basin11,948.017,337.325,363.93.3160.8160.70.0321.041,127.4Artificial Lift Engines5,100.97,887.366.51.343.643.6-51.4516.8December 2012112Basin/Source Category2011 Emissions (Tons per year)NOxCOVOCSO2PM10PM2.5H2SHAPsCH4Blowdowns--26.3----0.169.8Casinghead Gas Venting--19.6 ----0.1 50.5Condensate Tanks--10,583.9 ----50.9 2,425.4Crude Oil Tanks--297.2----7.241.6Dehydrators0.0 0.0 124.0 -0.00.0 -101.7 127.8Drill Rigs96.6 26.0 5.3 0.2 4.03.9 -0.7 0.1Fugitives--1,666.6----4.04,349.2Gas-Actuated Pumps--604.2 ----1.4 1,587.1Heaters798.1 670.4 43.9 -60.760.7 -6.1 18.4Hydraulic Fracturing---------Lateral/Gathering LineCompressors1,199.8 1,663.7 42.8 0.4 11.011.0 -15.7 417.7Loading Emissions--110.3 ---0.0 1.4 0.9Mud Degassing--170.6 ----0.4 351.1Pneumatic Devices--11,301.1 ----26.7 29,756.3Produced Water---------Well Completions--202.8 ----0.5 533.0Wellhead Compressor Engines4,752.5 7,089.8 98.7 1.4 41.641.6 -52.8 881.9Southern Oklahoma7,491.59,423.230,292.226.7194.7194.616.7377.056,053.5Artificial Lift Engines3,380.2 5,226.6 44.1 0.9 28.928.9 -34.0 342.5Blowdowns--1,906.1 0.5 ---3.3 10,495.8Casinghead Gas Venting--287.1 0.3 ----325.3Condensate Tanks22.9 120.9 1,092.9 ----26.5 1,047.2Crude Oil Tanks0.0 0.1 6,873.3 17.9 ---209.9 594.5Dehydrators0.00.022.0-0.00.0-18.022.6December 2012113Basin/Source Category2011 Emissions (Tons per year)NOxCOVOCSO2PM10PM2.5H2SHAPsCH4Drill Rigs75.817.94.70.13.02.9-0.60.1Fugitives--3,056.3 ---2.8 0.6 5,103.8Gas-Actuated Pumps--1,298.4 ---1.3 0.1 1,852.4Heaters1,635.11,373.589.90.0124.3124.3-12.637.6Hydraulic Fracturing14.7 3.3 0.9 0.0 0.60.6 -0.1 0.0Lateral/Gathering LineCompressors652.6 759.0 40.2 0.4 10.710.7 -15.6 431.2Loading Emissions--110.3---0.00.97.3Mud Degassing--159.1 ---0.2 0.0 205.5Pneumatic Devices--15,046.4 ---12.4 6.8 34,160.3Produced Water---------Well Completions11.7 62.1 143.2 5.5 ---6.7 172.7Wellhead Compressor Engines1,698.5 1,859.7 117.3 1.1 27.227.2 -41.2 1,254.6Western Gulf142,581.7187,678.0433,119.48,495.62,425.32,419.91,0106,969.1566,775.2Artificial Lift Engines7,071.5 10,934.3 92.2 1.8 60.560.5 -71.2 716.5Blowdowns--12,719.8 1.0 ---33.6 62,538.4Casinghead Gas Venting0.4 2.3 5,568.6 5,674.2 ---26.5 7,785.8Condensate Tanks355.0 1,876.6 232,906.5 ----2,506.4 93,676.2Crude Oil Tanks6.7 35.2 69,960.2 2,604.2 ---1,694.1 9,793.1Dehydrators0.0 0.0 104.5 -0.00.0 -114.0 119.2Drill Rigs4,611.3 1,163.1 274.8 9.1 185.3180.1 -34.0 4.4Fugitives--13,142.9 ---228.5 67.0 34,670.8Gas-Actuated Pumps--4,658.8 ---58.6 20.4 12,461.9Heaters9,973.7 8,377.9 548.6 0.0 758.0758.0 -76.8 229.4Hydraulic Fracturing163.436.910.30.36.46.2-1.30.2December 2012114Basin/Source Category2011 Emissions (Tons per year)NOxCOVOCSO2PM10PM2.5H2SHAPsCH4Lateral/Gathering LineCompressors8,920.812,806.4254.73.294.794.7-124.82,478.2Loading Emissions--4,084.2 ---0.0 45.7 122.0Mud Degassing--3,579.7 ---44.9 14.8 9,296.2Pneumatic Devices--70,510.7---622.1264.0257,480.2Produced Water--7,513.8 ---55.9 26.2 25,744.1Well Completions16.6 87.6 2,934.5 154.8 ---23.8 6,517.7Wellhead Compressor Engines111,462.4152,357.74,254.446.91,320.51,320.5-1,824.643,141.0Grand Total (rounded to thenearest whole number)836,1911,092,0201,616,98121,11017,40617,3748,00228,8913,708,820Emissions for the regional portion of each basin within each CenSARA State are shown in Table 7-2.Table 7-2. Emissions Inventory for 2011 oil and gas sources in CenSARA States.Basin/Source Category2011 Emissions (Tons per year)NOxCOVOCSO2PM10PM2.5H2SHAPsCH4AR9,048.56,482.19,227.7169.5289.6286.4204.8231.4136,216.5Arkoma Basin7,682.35,093.85,593.47.1230.8227.90.3129.3130,901.3Illinois Basin15.3 13.5 15.6 0.0 0.4 0.4 0.0 0.3372.7Louisiana-Mississippi Salt Basins1,350.9 1,374.7 3,618.6 162.5 58.4 58.1204.6 101.8 4,942.5Ozark Uplift- - - - - - - - -KS79,531.7104,801.3208,158.0145.52,172.82,172.1354.92,128.9548,165.2Anadarko Basin31,393.439,462.1 99,226.2 23.7 1,153.5 1,153.4 18.7 1,109.0 261,528.0Cambridge Arch-Central Kansas Uplift8,814.5 11,000.5 31,512.0 2.2 274.6 274.3 0.0 164.7 79,331.9Cherokee Platform19,295.525,686.3 36,924.6 114.4 415.2 415.1 314.0 424.5 131,460.5December 2012115Basin/Source Category2011 Emissions (Tons per year)NOxCOVOCSO2PM10PM2.5H2SHAPsCH4Forest City Basin4,313.76,048.67,891.51.088.588.411.457.118,637.9Nemaha Uplift3,684.5 5,180.9 6,704.2 0.9 76.1 76.010.0 50.8 15,111.9Salina Basin82.2 85.6 535.6 0.0 4.1 4.1 0.8 1.8967.6Sedgwick Basin11,948.017,337.325,363.93.3160.8160.70.0321.041,127.4LA42,316.252,600.5103,011.33,172.41,092.81,089.51,3242,643.2205,568.8Louisiana-Mississippi Salt Basins38,481.147,681.0 36,722.2 296.2 995.5 992.5 1,1991,624.4 153,658.4Western Gulf3,835.14,919.566,289.12,876.297.397.1124.81,018.951,910.4MO16.723.557.41.60.40.40.10.873.3Cherokee Platform2.5 3.4 18.9 1.6 0.1 0.1 0.1 0.4 11.5Forest City Basin14.220.138.60.00.30.30.00.461.9Illinois Basin---------Ozark Uplift- - - - - - - - -NE2,089.72,952.816,305.90.629.429.40.299.019,418.6Cambridge Arch-Central Kansas Uplift525.5 728.3 8,281.7 0.2 8.2 8.2 0.045.1 7,092.5Denver Basin1,547.2 2,203.1 7,693.4 0.4 20.8 20.80.2 52.4 11,984.2Forest City Basin17.021.4256.10.00.40.40.01.1315.0Nemaha Uplift- - - - - - - - -Salina Basin- - 74.7 - - - - 0.4 27.0OK71,339.988,497.6198,543.7533.22,069.62,067.4354.32,731.2617,260.1Anadarko Basin33,265.440,916.0 103,940.2 30.4 1,213.8 1,212.1 19.5 1,515.5 259,066.3Arkoma Basin7,933.2 7,368.0 10,680.2 10.2 197.8 197.4 3.2 211.5 163,325.1Bend Arch-Fort Worth Basin39.8 45.2 240.5 9.7 1.7 1.7 3.1 3.1298.8Cherokee Platform17,018.422,800.2 37,007.3 451.4 376.1 376.0 306.0 477.1 108,565.1Nemaha Uplift5,396.97,686.115,997.61.482.082.04.8141.528,671.5Palo Duro Basin194.5 258.8 385.7 3.4 3.6 3.6 0.9 5.6 1,279.8December 2012116Basin/Source Category2011 Emissions (Tons per year)NOxCOVOCSO2PM10PM2.5H2SHAPsCH4Southern Oklahoma7,491.59,423.230,292.226.7194.7194.616.7377.056,053.5TX631,848836,6621,081,67717,08711,75111,7295,76421,0562,182,117Anadarko Basin44,293.053,266.4 69,899.1 35.0 1,400.6 1,396.0 10.7 1,463.1 187,888.6Bend Arch-Fort Worth Basin143,992189,165.7147,405.81,657.62,467.22,463.11,1023,096.3458,243.6East Texas Basin128,840171,678.3100,631.5944.41,975.31,972.9439.83,417.4364,708.0Marathon Thrust Belt3,863.2 5,585.2 4,525.2 1.6 51.9 51.90.5 64.8 13,172.8Palo Duro Basin5,684.77,626.16,184.3203.491.291.236.9154.016,698.2Permian Basin166,428 226,582.7 386,201.5 8,625.6 3,437.3 3,431.6 3,288 6,910.9 626,541.9Western Gulf138,746 182,758.4 366,830.3 5,619.4 2,327.9 2,322.9 885.2 5,950.2 514,864.8Total CenSARA domain (rounded tothe nearest whole number)836,1911,092,0201,616,98121,11017,40617,3748,00228,8913,708,820December 2012



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## 7.2 Discussion

7.2.1 Major oil and gas area sources

Oil and gas activities in the upstream sector often involve the use of internal combustion engines and external combustion equipment during th e drilling and production phases such as compressor engines, drilling rigs, artificial lift engines, heaters, etc. Hence, several major

sources of NOx emissions can be found in this secto r. The CenSARA 2011 inventories suggest that in almost every basin, wellhead compressor eng ines are the largest source of NOx emissions across the CenSARA domain, representing o n average at least 50% of the total basinlevel NOx emissions in some of the basins such as P ermian, Western Gulf, Anadarko, Bend Arch

Fort Worth and East Texas. NOx sources are shown in Figure 7-1 for each basin.

Figure 7-1. NOx emissions by source category (in t ons per year).

Lateral compressors are another major source of NOx in the CenSARA region. NOx compressor emissions are generally large in older gas producin g basins that have lower wellhead pressures and thus higher compression requirements. The compr ession requirements of a basin are reflected in the usage fraction of wellhead compres sors and lateral compressors which varies significantly by basin. For wellhead compression, t his can range from 8 percent of wells requiring wellhead compressors in the Louisiana Mis sissippi Salt Flats to 99 percent of wells

0 20,000 40,000 60,000 80,000 100,000 120,000 140,000 160,000 180,000NOx Emission (TPY) WELL COMPLETIONS

WELLHEAD

COMPRESSOR ENGINES

CASINGHEAD GAS

VENTING

LATERAL/GATHERING

LINE COMPRESSORS

CRUDE OIL TANKS

HYDRAULIC

FRACTURING

HEATERS

BLOWDOWNS

DRILL RIGS

DEHYDRATORS

CONDENSATE TANKS

ARTIFICIAL LIFT

ENGINES BasinDecember 2012



### 118

requiring wellhead compression in some counties in Texas. Usage of lateral compressors is less common with usage fractions ranging from two percen t in the Salt Flats to 8 percent in Anadarko. Heaters also appear to be a major source of NOx emissions in the region, especially in the oil producing basins where this equipment is more commonly used. Vented gas sources in Figure 7-1 can have associated NOx emissions whe n flaring or other combustion-device controls are applied. In the current inventories, f laring emissions are embedded in many venting source categories such as well completions, condensate tanks, crude oil tanks, blowdowns and dehydrators.

VOCs emissions from venting and fugitives are commo nly emitted in upstream oil and gas operations. Other sources of VOCs include incomplet e fuel combustion in equipment such as engines and flares, but emissions from these are ve ry minimal compared to direct sources. The distribution of VOCs emissions by source category w ithin each basin is shown in Figure 7-2.

Figure 7-2. VOCs emissions by source category (in tons per year).

Major sources of VOC emissions vary greatly by basi n. Results suggest that the distribution of VOC emissions amongst area sources is highly depend ent on regional factors of the oil and gas producing regions that describe their production an d operations, that is, the concentration of VOCs in the produced gas, the amount of condensate production, the level of crude oil production, regional controls for venting sources, etc. One source that appears to be

0 50,000 100,000 150,000 200,000 250,000 300,000 350,000 400,000 450,000VOCs emissions (TPY) WELLHEAD COMPRESSOR

ENGINES
WELL COMPLETIONS

PRODUCED WATER

HEATERS

MUD DEGASSING

LOADING EMISSIONS

CASINGHEAD GAS VENTING

LATERAL/GATHERING LINE

COMPRESSORS
HYDRAULIC FRACTURING

DRILL RIGS

DEHYDRATORS

GAS-ACTUATED PUMPS

FUGITIVES

BLOWDOWNS

PNEUMATIC DEVICES

CONDENSATE TANKS

CRUDE OIL TANKS BasinDecember 2012



### 119

consistently significant for VOCs among all basins is pneumatic devices. The use of nobleed/low-bleed devices in each basin plays an impo rtant role in the level of VOC emissions from this source. This source is also driven by the well counts of each basin and the amount of VOCs in the gas. For example, the Anadarko, Western Gulf, Permian and Bend Arch-Fort Worth Basins have the largest numbers of active wells wit hin the CenSARA domain, and thus show a large portion of basin-wide VOC emissions coming fr om pneumatic devices. Another important

source of VOCs is related to tank losses for the st orage of condensate and crude oil. This is particularly relevant in basins with significant co ndensate and crude oil production such as Permian, Anadarko and Western Gulf. Basin-wide vent ing emissions from sources such as these, along with well completions, blowdowns and d ehydrators can be significantly reduced by regional practices on the use of controls involving capture and flaring. Some basins were found through the surveys to commonly control tank emissi ons by flare, such as Anadarko and Arkoma. Similarly, high concentrations of non-metha ne hydrocarbons in the produced gas from a basin can generally have a large impact on the ov erall VOC emissions of that region; thus, basins like Arkoma and Louisiana Mississippi Salt F lats which produce large amounts of dry gas (shale gas from the Fayetteville Shale and Haynesvi lle Shale) have a limited amount of VOCs emissions due to the low concentration of these pol lutants in the gas.

Methane is a gas species commonly emitted by area s ources in natural gas production facilities since it makes up the bulk of the mass of the produ ced gas. Similar to VOCs, the majority of methane emissions are originated by direct sources such as vented gas from blowdowns, well completions, pneumatic devices, gas actuated pumps, and fugitives. Unless capturing or flaring methods are used, these direct sources can release a significant amount of methane. Figure 7-3

shows all sources of methane for each of the CenSAR A basins. Results suggest that pneumatic devices are commonly the largest source of methane emissions across all basins. This is comparable to VOC emissions, as pneumatic devices b leed the produced gas which contains both methane and VOC pollutants. Another major sour ce of methane appears to be blowdowns and fugitives which are also direct sources. Blowdo wn emissions are driven by gas well counts and basin specific vent rates, hence basins that ha ve a substantial number of active gas wells such as Anadarko, Arkoma and Western Gulf, among ot hers, show large methane emissions for

this source.December 2012



### 120

Figure 7-3. Methane emissions by source category ( in tons per year).

7.2.2 Data Gap Findings

A series of data gaps have been identified during t he development of this regional inventory which affect the quality of emissions estimates. Th ere is an ongoing need for additional information at the basin level on equipment and act ivities related to oil and gas area emissions sources to address data gaps. Data gaps include inf ormation on equipment usage and size, local gas compositions, usage of control methods, venting rates for particular sources, etc.

Given the scope and resources of this Project, not all basins in the CenSARA region were part of the industry survey outreach and thus, those basins for which local data could not be gathered through industry surveys or any other means like pe rmit data, were based on national default literature values or regional averages of other bas ins (as delineated in Section 5.3.2). Similarly, a defined set of source categories were included in the surveys, those considered significant sources of air pollutants or “high-tier”, thus avai lability of local data for the remaining “lowtier” source categories was limited. Table 7-3 prov ides an assessment on the quality of the input data used to estimate emissions for key sourc es identified in this inventory. This evaluation is qualitative and based on the level of representativeness that each data input is 0 100,000 200,000 300,000 400,000 500,000 600,000 700,000 800,000Methane emissions (TPY) WELLHEAD COMPRESSOR

ENGINES

PRODUCED WATER

HEATERS

LOADING EMISSIONS

LATERAL/GATHERING LINE

COMPRESSORS

HYDRAULIC FRACTURING

CONDENSATE TANKS

DRILL RIGS

CRUDE OIL TANKS

ARTIFICIAL LIFT ENGINES

MUD DEGASSING

WELL COMPLETIONS

DEHYDRATORS

GAS-ACTUATED PUMPS

CASINGHEAD GAS

VENTING

PNEUMATIC DEVICES

BLOWDOWNS

FUGITIVESDecember 2012



### 121

believed to have for the basin it was applied to. T he following classifications have been made to evaluate input data:

x High: Data based on a significant number of useful survey entries for a particular source category and data field; or data obtained from the compilation of local data through state air agencies’ determinations.

x Medium: Data based on a limited number of survey en tries for a particular source category and data field; or data obtained through the compil ation and averaging of data from minor source permit applications. Permit applications wer e available for minor sources located at specific basins, and thus data from this informatio n source was regionally representative, although it may present the caveats of permit data (conservative assumptions, year of permit, etc.).

x Low: Data based on averages of all industry survey data available for a particular source category and data field regardless of the geographi cal specificity; or data based on default values derived from other regional or national emis sions inventory studies.

The analysis in Table 7-3 includes each of the surv eyed basins, as well as the non-surveyed basins which are divided in two distinctive groups: “other basins in Texas (except Permian and Marathon Thrust Belt)”, and “non-surveyed basins ou tside of Texas”. As explained in Section 5.3.2, input data was managed differently for basin s in each of these two groups; for instance, basin-specific averaging rules (Table 5-5) were app lied to data fields for non-surveyed basins outside of Texas. Nevertheless, input values for ba sins in this group were derived from regional averages and thus fall under the “low” quality inpu t data classification. The Marathon Thrust Belt is a small basin bordering south of the Permia n and it is assumed to have very similar operational characteristics to it, thus, MTB data i s assumed to be equivalent to that of the Permian basin, which may qualify from high to low d epending on the source of data for Permian. For “other basins in Texas”, data sources varied on a case by case basis. Many source categories inventoried in this study have not yet b een included in previous Texas inventories and thus averages of survey data were applied in th ese cases, while when regional data from other studies were available, these were used. Base d on this, Texas’ basins input data may be classified under the various designations shown abo ve.December 2012122Table 7-3. Quality assessment of input data used to estimate emissions for each area source categoryand basin in CenSARA.Source CategoryData field/InputsAnadarkoBasinArkomaBasinCambridgeArchCentralKansasUpliftPermianBasin (andMarathonThrustBelt)LouisianaMississippiSalt BasinsSedgwickBasinOtherbasins inTexas(exceptPermianand MTB)Nonsurveyed basinsoutsideofTexasARTIFICIAL LIFT ENGINESFraction of oil wells with artificiallift engines high low high low medium medium low lowARTIFICIAL LIFT ENGINESRated Horsepower high low high low medium high highlowARTIFICIAL LIFT ENGINESAnnual Activity (hours/yr) high medium high low medium high high lowARTIFICIAL LIFT ENGINESLoad FactorhighlowhighlowmediumhighhighlowARTIFICIAL LIFT ENGINES % of artificial lift engines that areelectrified medium low high low medium medium highlowARTIFICIAL LIFT ENGINESEmissions Factors (g/hp-hr) low low low low low lowhigh lowWELLHEAD COMPRESSORSFraction of wells with wellheadcompressors high medium low medium medium low low lowWELLHEAD COMPRESSORS Annual Activity (hr) high medium low low medium medium high lowWELLHEAD COMPRESSORSFraction Rich Burn (RB) versusLean Burn (LB) medium medium low medium low low high lowWELLHEAD COMPRESSORS - LEANLB Rated HorsepowerhighmediumlowlowlowlowhighlowWELLHEAD COMPRESSORS - LEAN LB Load Factor low medium low low low low high lowWELLHEAD COMPRESSORS - LEAN % LB Engines Controlledmedium medium low low low low high lowWELLHEAD COMPRESSORS - LEANCO Control Factor Cat. OxidizerlowlowlowlowlowlowhighlowWELLHEAD COMPRESSORS - LEAN LB Emissions Factors (g/hp-hr) low low low low low low high lowWELLHEAD COMPRESSORS - RICH RB Rated Horsepower highmedium low low medium low high lowWELLHEAD COMPRESSORS - RICH RB Load Factor medium medium low low medium low high lowWELLHEAD COMPRESSORS - RICH % RB Engines Controlledmedium medium low low low low high lowWELLHEAD COMPRESSORS - RICHNOx, CO Control Factor NSCRmediummediumlowlowlowlowhighlowWELLHEAD COMPRESSORS - RICH VOC Control Factor NSCRmedium medium low low low low high lowWELLHEAD COMPRESSORS - RICH RB Emissions Factors (g/hp-hr) low low low low low low high lowDecember 2012123Source CategoryData field/InputsAnadarkoBasinArkomaBasinCambridgeArchCentralKansasUpliftPermianBasin (andMarathonThrustBelt)LouisianaMississippiSalt BasinsSedgwickBasinOtherbasins inTexas(exceptPermianand MTB)Nonsurveyed basinsoutsideofTexasLATERAL/GATHERING COMPRESSORSNo. wells served by a single lateralcompressor medium medium medium low medium low lowlowLATERAL/GATHERING COMPRESSORSAnnual Activity (hr)mediummediummediumlowmediumlowlowlowLATERAL/GATHERING COMPRESSORSFraction Rich Burn (RB) versus LeanBurn (LB) medium medium low low medium low low lowLATERAL/GATHERING COMPRESSORS -LEAN BURNLB Rated HorsepowermediumlowmediumlowlowlowlowlowLATERAL/GATHERING COMPRESSORS -LEAN BURN LB Load Factor medium medium medium low medium low low lowLATERAL/GATHERING COMPRESSORS -LEAN BURN% LB Engines ControlledmediummediumlowlowmediumlowlowlowLATERAL/GATHERING COMPRESSORS -LEAN BURN CO Control Factor Cat. Oxidizer low low low low low low low lowLATERAL/GATHERING COMPRESSORS -LEAN BURNLB Emissions Factors (g/hp-hr)lowlowlowlowlowlowlowlowLATERAL/GATHERING COMPRESSORS -RICH BURN RB Rated Horsepower low medium medium lowmedium low low lowLATERAL/GATHERING COMPRESSORS -RICH BURNRB Load FactorlowlowmediumlowlowlowlowlowLATERAL/GATHERING COMPRESSORS -RICH BURN % RB Engines Controlled medium medium lowlow medium low low lowLATERAL/GATHERING COMPRESSORS -RICH BURNNOx, CO Control Factor NSCRmediummediumlowlowmediumlowlowlowLATERAL/GATHERING COMPRESSORS -RICH BURN VOC Control Factor NSCR medium medium lowlow medium low low lowLATERAL/GATHERING COMPRESSORS -RICH BURNRB Emissions Factors (g/hp-hr)lowlowlowlowlowlowlowlowDecember 2012124Source CategoryData field/InputsAnadarkoBasinArkomaBasinCambridgeArchCentralKansasUpliftPermianBasin (andMarathonThrustBelt)LouisianaMississippiSalt BasinsSedgwickBasinOtherbasins inTexas(exceptPermianand MTB)Nonsurveyed basinsoutsideofTexasDRILLING RIGSFraction of drill-rigs that are dieselelectric medium low low low low low low lowDRILLING RIGSIndividual data on engines forhorizontal and vertical drilling medium medium lowlow low low low lowDRILLING RIGS Number of engines per rig high high medium low medium low low lowDRILLING RIGS Depth per spud (ft) medium medium medium low medium low low lowDRILLING RIGSRated Horsepower (hp) for eachengine high high medium low medium low low lowDRILLING RIGS Load Factors medium medium medium lowmedium low low lowDRILLING RIGS Hours of use (hr/spud) per engine medium medium medium low medium low low lowDRILLING RIGS Emissions Factors (g/hp-hr) medium medium medium medium medium medium medium mediumCONDENSATE TANKSFraction of Production to TankslowlowlowlowlowlowlowlowCONDENSATE TANKS Fraction of Tanks Flared high medium low low medium low low lowCONDENSATE TANKS VOC Fraction of the flash gas medium medium medium low medium medium low lowCONDENSATE TANKSAverage losses per unit throughput(lb-VOC/bbl of condensate)highmediummediumhighmediummediumhighlowCONDENSATE TANKSCondensate tank flash gascomposition medium medium medium low medium mediumlow lowWELL COMPLETIONSVolume of Gas Vented PerCompletion (MCF/event)uncontrolledmediumhighhighlowmediumlowlowlowWELL COMPLETIONS Fraction of Completions with Flaring medium high high low medium low low lowWELL COMPLETIONSFraction of Completions with GreenCompletion medium high high low medium low low lowWELL COMPLETIONSFlaring Control Efficiency (%)lowhighhighlowlowlowlowlowWELL COMPLETIONS Flaring Capture Efficiency (%) lowhigh high low low low low lowDecember 2012125Source CategoryData field/InputsAnadarkoBasinArkomaBasinCambridgeArchCentralKansasUpliftPermianBasin (andMarathonThrustBelt)LouisianaMississippiSalt BasinsSedgwickBasinOtherbasins inTexas(exceptPermianand MTB)Nonsurveyed basinsoutsideofTexasWELL COMPLETIONSCriteria pollutant and GHGsspeciation of vented gas high high high medium highhigh low lowWELL COMPLETIONSHAPS speciation of vented gasmediumlowlowlowmediumlowlowlowWELL COMPLETIONS Local Heating Value (BTU/SCF) medium high high low medium low low lowWELL COMPLETIONS Molecular Weight of the Gas medium low low low medium low low lowHYDRAULIC FRACTURING Rated Horsepower low medium medium low low low low lowHYDRAULIC FRACTURING Load Factor low medium low lowlow low low lowHYDRAULIC FRACTURINGNo. Stages per Well (stages/well)lowmediummediumlowlowlowlowlowHYDRAULIC FRACTURING Duration per Stage (hr/stage)low medium medium low low low low lowHYDRAULIC FRACTURING No. Engines Used per Fracing Event low medium medium low low low low lowHYDRAULIC FRACTURING Total HP-HR per well medium medium medium low low low low lowBLOWDOWNSAverage Blowdown Frequency(events/well-year)mediummediumlowmediummediummediumlowlowBLOWDOWNSVolume of Gas Vented PerBlowdown (MCF/event)uncontrolled medium medium low medium medium mediumlow lowBLOWDOWNSFraction of Blowdowns that areControlledmediummediumlowmediumlowlowlowlowBLOWDOWNS Control Method Efficiency (%) low low lowlow low low low lowBLOWDOWNSCriteria pollutant and GHGsspeciation of vented gas high high high medium highhigh low lowBLOWDOWNS HAPS speciation of vented gas medium lowlow low medium low low lowCASING GASVenting Rate of Casing Gas per Unitof Oil Production (MCF/bbl) medium low medium low low medium low lowCASING GASFraction of Vents Controlled byFlaring (Fflare) low low medium low low medium lowlowDecember 2012126Source CategoryData field/InputsAnadarkoBasinArkomaBasinCambridgeArchCentralKansasUpliftPermianBasin (andMarathonThrustBelt)LouisianaMississippiSalt BasinsSedgwickBasinOtherbasins inTexas(exceptPermianand MTB)Nonsurveyed basinsoutsideofTexasCASING GAS Flaring Control Efficiency (%) low low low low low low low lowCASING GAS Flaring Capture Efficiency (%) low low low low low low low lowPNEUMATIC DEVICESNo. of Devices by Bleed RateClassificationmediummediumlowmediummediumlowlowlowPNEUMATIC DEVICES Bleed Rates (by device) low low low low low low low lowPNEUMATIC DEVICESCriteria pollutant and GHGsspeciation of vented gas high high high medium highhigh low lowPNEUMATIC DEVICES HAPS speciation of vented gas medium low low low medium low low lowDEHYDRATORSFraction of Dehydrators with FlareslowlowlowlowlowlowlowlowDEHYDRATORSStill Vent VOC Emissions (lbVOC/MMSCF) medium medium medium low medium medium low lowDEHYDRATORS Heater MMBTU Rating (MMBTU/hr) medium medium medium low low low low lowDEHYDRATORSLocal Heating Value (BTU/SCF)mediummediummediumlowmediummediumlowlowDEHYDRATORS Annual Heater Usage (hr) medium mediummedium low low low low lowDEHYDRATORS Dehydrator still vent gas speciation low low low low low low low lowDEHYDRATORSDehydrator reboiler emissionsfactors (lb/MMSCF)lowlowlowlowlowlowlowlowCRUDE TANKS Fraction of Production to Tanks low lowlow low low low low lowCRUDE TANKS Fraction of Tanks Flared medium mediummedium medium medium medium low lowCRUDE TANKSAverage Loss Emissions (lbVOC/bbl)mediummediummediumlowmediummediumlowlowCRUDE TANKS Local Heating Value (BTU/SCF) medium medium low low medium low low lowCRUDE TANKS VOC fraction of the gas medium medium low low medium low low lowCRUDE TANKS Molecular weight of the gas medium medium low low medium low low lowCRUDE TANKSOil tank losses gas analysis - CriteriaPollutants and GHGs medium medium low low medium low low lowDecember 2012127Source CategoryData field/InputsAnadarkoBasinArkomaBasinCambridgeArchCentralKansasUpliftPermianBasin (andMarathonThrustBelt)LouisianaMississippiSalt BasinsSedgwickBasinOtherbasins inTexas(exceptPermianand MTB)Nonsurveyed basinsoutsideofTexasCRUDE TANKSOil tank losses gas analysis - HAPsspeciation low medium low low medium low low lowGAS-ACTUATED PUMPSKimray pumps venting rate per unitthroughput (SCF-CH4/MMSCF gas) low low low low low low low lowGAS-ACTUATED PUMPSAnnual gas pumped per well(MMSCF/yr/well) low low low low low low low lowGAS-ACTUATED PUMPSChemical injection pump ventingrate per pump (SCF-CH4/pump/day) low low low low low low low lowGAS-ACTUATED PUMPSAverage number of pumps pergas/oil well low low low low low low low lowGAS-ACTUATED PUMPSCriteria pollutant and GHGsspeciation of vented gas high high high medium highhigh low lowGAS-ACTUATED PUMPS HAPS speciation of vented gas medium low low low medium low low lowFUGITIVESNo. of devices per typical well bydevice type and by service medium medium medium medium medium low low lowFUGITIVESPollutant to TOC fraction in leakedgas - criteria pollutants and GHGs high high high medium high high low lowFUGITIVESPollutant to TOC fraction in leakedgas - HAPs medium low low low medium low low lowFUGITIVESCompressor seals leaking rate perengine (SCF-CH4/hr/compressor) low low low low lowlow low lowFUGITIVESFraction of wells serviced bywellhead compressors high medium low medium mediumlow low lowFUGITIVESNo. wells served by single lateralcompressor [wells/compressor] medium medium mediumlow medium low low lowFUGITIVES Annual Activity (hr) low low low low lowlow low lowDecember 2012



### 128

Data fields with “low quality” designation would be nefit from further research and collection of operator data. These fields are generally in source categories that, individually, are not the most significant area sources of key pollutants (VO C, NOx) but combined provide a significant

emissions contribution to area source inventories. These data are also generally poorly characterized at the basin level in many oil and ga s inventories, thus making it difficult to find regionally-representative data in the literature.

The quality of survey data was greatly affected by the level of response from operators. This is not only manifested through the number of operators that returned survey forms for each basin, but also by the actual number of survey data requests that were completed and proved useful towards deriving basin-wide input values. So me source categories received a larger number of responses than others, and this in additi on varied by basin. Surveys for artificial lifts, drilling rigs, wellhead compressors, condensate tan ks, and well completions yielded a good level of responsiveness in terms of participating c ompanies and the amount of data provided. Other source categories did not have such a good re sponse rate, such as dehydrators, lateral compressors and hydraulic fracturing pumps. Moreove r, with some source categories surveys only partially completed, certain data fields withi n a source category yielded different levels of response and quality than other fields. This sugges ts the importance of survey outreach to be wide-ranging and supported by incentives for operat ors to fully collaborate in the provision of high quality and complete data.

Results suggest much of VOC and HAPs are generated by direct emissions from venting and fugitive sources, thus speciation of the local gas is essential to accurately characterize those emissions. This requires the compilation of local g as compositions at various points throughout natural gas and oil systems where these emissions o ccur; for example wellhead venting, piping and equipment emissions at the well-site, flashing and breathing emissions from oil/condensate tanks, and venting from gas dehydration. Gas analys es for vented gas from tanks and dehydrators are scarce and highly dependent on the basin where the gas is produced, thus it is imperative data is compiled by basin.

7.2.3 Future work opportunities

Many source categories would benefit from future wo rk that aims at collecting updated regional field level data for certain sources withi n the CenSARA domain. Improvements are

needed to better understand emissions from source c ategories associated with hydraulic fracturing such as well completions and frac pump e ngines as this region houses several key unconventional gas resources that require hydraulic fracturing. Available oil and gas emissions studies suggest that fugitive emissions are also no t well characterized and regional and detailed emissions factors are yet to be developed for this source. Fugitive leaking rates used in this inventory and commonly used in other available inve ntories are based on EPA and GRI studies from the 1990’s and may not be representative of co nditions at many unconventional gas wells. Additional research is needed to improve these fugi tive emissions factors. Produced water is perhaps one of the most poorly understood source ca tegories. This includes holding ponds or tanks, evaporation ponds, and wastewater disposal f acilities. Evolution of VOC emissions from produced water may be a significantly underestimate d source category in the CenSARA domain,December 2012



### 129

especially in those basins housing shale gas plays where water consumption and production is high. In addition, water production statistics are not recorded consistently throughout all CenSARA states, thus restricting the ability of cha racterizing produced water emissions at the basin-level. Mud degassing is another poorly-unders tood VOC emissions source. The recent EPA Subpart W reporting requirements for GHG emissi ons from oil and gas systems could yield significant quantities of detailed data on equipmen t, processes and gas compositions that could be used to extract regionally specific data on this source (and many others) within the CenSARA

domain.

A survey outreach is a recommended method to collec ting data; however the efficacy of data collection will always be tied to the level of resp onsiveness and collaboration from oil and gas operators. Thus it is imperative that state agencie s provide incentives and support to surveyed companies to encourage their participation. Certain key categories could benefit from additional information, particularly usage fraction s of wellhead and lateral compressors within certain basins, manufacturer emissions factors for stationary compressors, and engine configurations and usage data for drilling rigs. F or VOC emissions source categories, fugitive emissions represent one of the least studied emissi ons sources. It should be noted that significant quantity and detail of data on equipmen t, usage, configuration, and processes has now been gathered for the first time by EPA as part of Subpart W reporting of GHG emissions by oil and gas companies. To the extent that this data is made available to state agencies or the public for use in future emissions inventories, it may allow for checks on assumptions used in this inventory as well as revisions to lower qualit y input data.

Direct measurement of emissions rates and derivatio n of emissions factors from measured or monitored data is likely to produce accurate and re gionally specific data but it is often not feasible to conduct this type of data collection fr om a large group of sources operating in a broad geographic region. When possible, direct mea surement studies could be conducted to further characterize basin-wide average emission fa ctors.December 2012



### 130



## 8.0 CONCLUSIONS

Oil and gas area source emissions inventories were developed in this work for oil and gas producing states within the CenSARA region. These i nventories included a substantial level of detail in terms of geographical specificity (detail by basin, state and county), in the array of pollutants included (16 total) and the number of so urce categories analyzed (18 area sources, 34 SCCs). The development of detailed emissions inv entories by source category led to several key conclusions:

x NOx emissions are dominated by wellhead compressors , particularly for gas producing basins with a large number of active gas wells;

x Other significant sources of NOx include lateral co mpressors and heaters, followed by drilling rigs and artificial lift engines;

x Other NOx emissions sources (e.g. flaring of vented sources and hydraulic fracturing engines) do not appear to contribute significantly to NOx emissions across the CenSARA domain;

x Pneumatic devices are the most significant source o f VOC and methane emissions in most basins. In basins where the production of condensat e and crude oil is extraordinary (Permian and Western Gulf), VOC emissions are domin ated by condensate tank and crude oil tank losses;

x The VOC fraction of the gas and the use of flaring controls appear to be key variables in determining total VOC emissions with a basin (Arkom a, for example, has low VOC emissions relative to its substantial gas production, due to the low VOC content of the gas and flaring controls on condensate tanks).

x Other significant VOC and methane emissions source categories include blowdowns, fugitive emissions and wellhead compressor engine e xhaust gas, particularly from lean burn
compressor engines.

A series of data gaps were identified during the de velopment of this work that ultimately affect the quality of emissions estimates in the inventory . This is related to an ongoing need for additional information at the basin level for equip ment and activities specific to that basin’s oil and gas area emissions sources. Some of the surveye d basin response levels in this work were relatively thorough while others were incomplete or not surveyed at all. Many source categories would benefit from future work that aims at collecting additional regional or basinlevel data within the CenSARA domain. Work is also needed to better characterize emissions from source categories not surveyed in this study i ncluding fugitives, mud degassing and produced water . Future efforts should target gathe ring basin specific data so that higher quality calculation inputs may be developed and app lied in the Emissions Calculator Tool developed here, enabling an effective and more accu rate estimation of future year inventories

for the CenSARA domain.December 2012



### 131



## 9.0 REFERENCES

Bar-Ilan, A., R. Parikh, J. Grant, T. Shah, and A. Pollack. 2008. “Recommendations for Improvements to the CENRAP States’ Oil and Gas Emis sions Inventories.” ENVIRON.

Accessed online at: http://www.wrapair.org/forums/ogwg/documents/2008- 11_CENRAP_O&G_Report_11-13.pdf

Drillinginfo, Inc. 2012. “DI Desktop Database power ed by HPDI.” Internet address: http://www.didesktop.com/

Eastern Research Group, 2009. “Drilling Rig Emissio n Inventory for the State of Texas.” Final Report. Prepared for Texas Commission on Environmen tal Quality (TCEQ). Accessed

online at: http://www.tceq.state.tx.us/assets/public/implement ation/air/am/contracts/reports/ei /5820783985FY0901-20090715-ergi-Drilling_Rig_EI.pdf

Eastern Research Group, 2010. “Characterization of Oil and Gas Production Equipment and Develop a Methodology to Estimate Statewide Emissio ns.” Final Report for the Texas Commission on Environmental Quality, November 24, 2 010. Accessed online at: http://www.tceq.texas.gov/assets/public/implementat ion/air/am/contracts/reports/ei/ 5820784003FY1026-20101124-ergi-oilGasEmissionsInven tory.pdf.

Eastern Research Group. 2012. “Condensate Tank Oil and Gas Activities.” Final Report. Prepared for the Texas Commission on Environmental Quality. October 10, 2012. Available online

at: http://www.tceq.texas.gov/assets/public/implementat ion/air/am/contracts/reports/ei/ 5821199776FY1211-20121031-ergi-condensate_tank.pdf

Energy Information Administration (EIA). 2012. Acce ssed online at: http://www.eia.gov/

ENVIRON International Corporation. 2009. “Developme nt of Emissions Inventories for Natural Gas Exploration and Production Activity in the Hayn esville Shale.” Draft Report to the Northeast Texas Air Care. , August 31, 2009. Access ed online at: http://www.netac.org/UserFiles/File/NETAC/9_29_09/E nclosure_2b.pdf

ENVIRON International Corporation. 2012. “Emissions from Natural Gas Exploration and Production Activity in the Haynesville Shale.” Draf t Report (In Progress). Prepared for the East Texas Council of Governments. December 19, 2012.

The Climate Registry, 2010. “Oil and Gas Production Protocol, Annex II to the General Reporting Protocol, Version 1.0”. The Climate Registry, 2010. Internet address: http://www.theclimateregistry.org/downloads/2010/04 /Final-OGP-Protocol.pdf

U.S. Environmental Protection Agency, 1991. “AP 42, Fifth Edition, Volume I, Chapter 13: Miscellaneous Sources, Section 13.5 Industrial Flar es,” U.S. Environmental Protection Agency, Research Triangle Park, NC, 1991. Internet address: http://www.epa.gov/ttn/chief/ap42/ch13/final/c13s05 .pdfDecember 2012



### 132

U.S. Environmental Protection Agency, 1995. “Protoc ol for Equipment Leak Emission Estimates,” U.S. Environmental Protection Agency, R esearch Triangle Park, NC, 1995.

Internet address: http://www.epa.gov/ttn/chief/efdocs/equiplks.pdf

U.S. Environmental Protection Agency, 1998. “AP 42, Fifth Edition, Volume I, Chapter 1: External Combustion Sources,” U.S. Environmental Protection Agency, Research Triangle Park, NC, 1998. Internet address: http://www.epa.gov/ttn/chief/ap42/ch01/index.html

U.S. Environmental Protection Agency, 2000. “AP 42, Fifth Edition, Volume I, Chapter 3: Stationary Internal Combustion Sources,” U.S. Envir onmental Protection Agency, Research Triangle Park, NC, 2000. Internet address: http://www.epa.gov/ttn/chief/ap42/ch03/index.html

U.S. Environmental Protection Agency, 2005. “User’s Guide for the Final NONROAD2005 Model,” U.S. Environmental Protection Agency, Resea rch Triangle Park, NC, 2005. EPA

420-R-05-013.

U.S. Environmental Protection Agency, 2006a. “Insta lling Plunger Lift Systems in Gas Wells.”

Lessons Learned from Natural Gas STAR Partners. Oct ober. Accessed online at: http://epa.gov/gasstar/documents/ll_plungerlift.pdf

U.S. Environmental Protection Agency, 2006b. “Speci ate 4.0 Speciation Database Development Documentation,” U.S Environmental Protection Agency , Research Triangle Park, NC, November 2006. EPA/600/R-06/161

U.S. Environmental Protection Agency, 2008. “AP 42, Fifth Edition, Volume I, Chapter 5: Petroleum Industry, Section 5.2 Transportation and Marketing of Petroleum Liquids,” U.S. Environmental Protection Agency, Research Tria ngle Park, NC, 2008. Internet

address: http://www.epa.gov/ttn/chief/ap42/ch05/final/c05s02 .pdf

U.S. Environmental Protection Agency (EPA). 2011. “ Inventory of Greenhouse Gas Emissions and Sinks: 1990-2009”, Washington DC, April. Access ed online at: http://www.epa.gov/climatechange/emissions/download s11/US-GHG-Inventory-2011- Complete_Report.pdf

U.S. Environmental Protection Agency, 2012. “Invent ory of Greenhouse Gas Emissions and Sinks: 1990-2010,” Washington DC, April. Accessed o nline at: http://www.epa.gov/climatechange/emissions/usinvent oryreport.html

Western Regional Air Partnership (WRAP). 2012. “Pha se III Inventories for the Rocky Mountain Region.” Prepared by ENVIRON International Corporat ion. Basin-specific reports

available at: http://wrapair2.org/PhaseIII.aspxDecember 2012



## APPENDIX A

CenSARA States County ListDecember 2012



### A-1



## Appendix A: CenSARA States County List

This includes counties that have not yet been assig ned to a Basin.

Table A-1. List of counties in each CenSARA State including Basin designation.

FIPS Code State County Basin

05001 AR Arkansas Louisiana-Mississippi Salt Basins

05003 AR Ashley Louisiana-Mississippi Salt Basins

05005 AR Baxter Ozark Uplift

05007 AR Benton Ozark Uplift

05009 AR Boone Ozark Uplift

05011 AR Bradley Louisiana-Mississippi Salt Basins

05013 AR Calhoun Louisiana-Mississippi Salt Basins

05015 AR Carroll Ozark Uplift

05017 AR Chicot Louisiana-Mississippi Salt Basins

05019 AR Clark Louisiana-Mississippi Salt Basins

05021 AR Clay Illinois Basin

05023 AR Cleburne Arkoma Basin

05025 AR Cleveland Louisiana-Mississippi Salt Basins

05027 AR Columbia Louisiana-Mississippi Salt Basins

05029 AR Conway Arkoma Basin

05031 AR Craighead Illinois Basin

05033 AR Crawford Arkoma Basin

05035 AR Crittenden Illinois Basin

05037 AR Cross Illinois Basin

05039 AR Dallas Louisiana-Mississippi Salt Basins

05041 AR Desha Louisiana-Mississippi Salt Basins

05043 AR Drew Louisiana-Mississippi Salt Basins

05045 AR Faulkner Arkoma Basin

05047 AR Franklin Arkoma Basin

05049 AR Fulton Ozark Uplift

05051 AR Garland Arkoma Basin

05053 AR Grant Louisiana-Mississippi Salt Basins

05055 AR Greene Illinois Basin

05057 AR Hempstead Louisiana-Mississippi Salt Basins

05059 AR Hot Spring Louisiana-Mississippi Salt Basins

05061 AR Howard Louisiana-Mississippi Salt Basins

05063 AR Independence Arkoma Basin

05065 AR Izard Ozark Uplift

05067 AR Jackson Illinois Basin

05069 AR Jefferson Louisiana-Mississippi Salt BasinsDecember 2012



### A-2

FIPS Code State County Basin

05071 AR Johnson Arkoma Basin

05073 AR Lafayette Louisiana-Mississippi Salt Basins

05075 AR Lawrence Ozark Uplift

05077 AR Lee Illinois Basin

05079 AR Lincoln Louisiana-Mississippi Salt Basins

05081 AR Little River Louisiana-Mississippi Salt Basins

05083 AR Logan Arkoma Basin

05085 AR Lonoke Arkoma Basin

05087 AR Madison Arkoma Basin

05089 AR Marion Ozark Uplift

05091 AR Miller Louisiana-Mississippi Salt Basins

05093 AR Mississippi Illinois Basin

05095 AR Monroe Illinois Basin

05097 AR Montgomery Arkoma Basin

05099 AR Nevada Louisiana-Mississippi Salt Basins

05101 AR Newton Arkoma Basin

05103 AR Ouachita Louisiana-Mississippi Salt Basins

05105 AR Perry Arkoma Basin

05107 AR Phillips Illinois Basin

05109 AR Pike Louisiana-Mississippi Salt Basins

05111 AR Poinsett Illinois Basin

05113 AR Polk Arkoma Basin

05115 AR Pope Arkoma Basin

05117 AR Prairie Arkoma Basin

05119 AR Pulaski Arkoma Basin

05121 AR Randolph Ozark Uplift

05123 AR St. Francis Illinois Basin

05125 AR Saline Arkoma Basin

05127 AR Scott Arkoma Basin

05129 AR Searcy Arkoma Basin

05131 AR Sebastian Arkoma Basin

05133 AR Sevier Louisiana-Mississippi Salt Basins

05135 AR Sharp Ozark Uplift

05137 AR Stone Arkoma Basin

05139 AR Union Louisiana-Mississippi Salt Basins

05141 AR Van Buren Arkoma Basin

05143 AR Washington Arkoma Basin

05145 AR White Arkoma Basin

05147 AR Woodruff Illinois Basin

05149 AR Yell Arkoma BasinDecember 2012



### A-3

FIPS Code State County Basin

20001 KS Allen Cherokee Platform

20003 KS Anderson Forest City Basin

20005 KS Atchison Forest City Basin

20007 KS Barber Sedgwick Basin

20009 KS Barton Cambridge Arch-Central Kansas Uplift

20011 KS Bourbon Cherokee Platform

20013 KS Brown Forest City Basin

20015 KS Butler Nemaha Uplift

20017 KS Chase Nemaha Uplift

20019 KS Chautauqua Cherokee Platform

20021 KS Cherokee Cherokee Platform

20023 KS Cheyenne Cambridge Arch-Central Kansas Uplift

20025 KS Clark Anadarko Basin

20027 KS Clay Salina Basin

20029 KS Cloud Salina Basin

20031 KS Coffey Forest City Basin

20033 KS Comanche Anadarko Basin

20035 KS Cowley Nemaha Uplift

20037 KS Crawford Cherokee Platform

20039 KS Decatur Cambridge Arch-Central Kansas Uplift

20041 KS Dickinson Salina Basin

20043 KS Doniphan Forest City Basin

20045 KS Douglas Forest City Basin

20047 KS Edwards Anadarko Basin

20049 KS Elk Cherokee Platform

20051 KS Ellis Cambridge Arch-Central Kansas Uplift

20053 KS Ellsworth Cambridge Arch-Central Kansas Uplift

20055 KS Finney Anadarko Basin

20057 KS Ford Anadarko Basin

20059 KS Franklin Forest City Basin

20061 KS Geary Nemaha Uplift

20063 KS Gove Anadarko Basin

20065 KS Graham Cambridge Arch-Central Kansas Uplift

20067 KS Grant Anadarko Basin

20069 KS Gray Anadarko Basin

20071 KS Greeley Anadarko Basin

20073 KS Greenwood Cherokee Platform

20075 KS Hamilton Anadarko Basin

20077 KS Harper Sedgwick Basin

20079 KS Harvey Sedgwick BasinDecember 2012



### A-4

FIPS Code State County Basin

20081 KS Haskell Anadarko Basin

20083 KS Hodgeman Anadarko Basin

20085 KS Jackson Forest City Basin

20087 KS Jefferson Forest City Basin

20089 KS Jewell Salina Basin

20091 KS Johnson Forest City Basin

20093 KS Kearny Anadarko Basin

20095 KS Kingman Sedgwick Basin

20097 KS Kiowa Anadarko Basin

20099 KS Labette Cherokee Platform

20101 KS Lane Anadarko Basin

20103 KS Leavenworth Forest City Basin

20105 KS Lincoln Salina Basin

20107 KS Linn Forest City Basin

20109 KS Logan Anadarko Basin

20111 KS Lyon Forest City Basin

20113 KS McPherson Sedgwick Basin

20115 KS Marion Sedgwick Basin

20117 KS Marshall Nemaha Uplift

20119 KS Meade Anadarko Basin

20121 KS Miami Forest City Basin

20123 KS Mitchell Salina Basin

20125 KS Montgomery Cherokee Platform

20127 KS Morris Nemaha Uplift

20129 KS Morton Anadarko Basin

20131 KS Nemaha Nemaha Uplift

20133 KS Neosho Cherokee Platform

20135 KS Ness Anadarko Basin

20137 KS Norton Cambridge Arch-Central Kansas Uplift

20139 KS Osage Forest City Basin

20141 KS Osborne Salina Basin

20143 KS Ottawa Salina Basin

20145 KS Pawnee Cambridge Arch-Central Kansas Uplift

20147 KS Phillips Cambridge Arch-Central Kansas Uplift

20149 KS Pottawatomie Nemaha Uplift

20151 KS Pratt Cambridge Arch-Central Kansas Uplift

20153 KS Rawlins Cambridge Arch-Central Kansas Uplift

20155 KS Reno Sedgwick Basin

20157 KS Republic Salina Basin

20159 KS Rice Cambridge Arch-Central Kansas UpliftDecember 2012



### A-5

FIPS Code State County Basin

20161 KS Riley Nemaha Uplift

20163 KS Rooks Cambridge Arch-Central Kansas Uplift

20165 KS Rush Cambridge Arch-Central Kansas Uplift

20167 KS Russell Cambridge Arch-Central Kansas Uplift

20169 KS Saline Salina Basin

20171 KS Scott Anadarko Basin

20173 KS Sedgwick Sedgwick Basin

20175 KS Seward Anadarko Basin

20177 KS Shawnee Forest City Basin

20179 KS Sheridan Cambridge Arch-Central Kansas Uplift

20181 KS Sherman Cambridge Arch-Central Kansas Uplift

20183 KS Smith Salina Basin

20185 KS Stafford Cambridge Arch-Central Kansas Uplift

20187 KS Stanton Anadarko Basin

20189 KS Stevens Anadarko Basin

20191 KS Sumner Sedgwick Basin

20193 KS Thomas Cambridge Arch-Central Kansas Uplift

20195 KS Trego Cambridge Arch-Central Kansas Uplift

20197 KS Wabaunsee Nemaha Uplift

20199 KS Wallace Anadarko Basin

20201 KS Washington Salina Basin

20203 KS Wichita Anadarko Basin

20205 KS Wilson Cherokee Platform

20207 KS Woodson Cherokee Platform

20209 KS Wyandotte Forest City Basin

22001 LA Acadia Western Gulf

22003 LA Allen Western Gulf

22005 LA Ascension Western Gulf

22007 LA Assumption Western Gulf

22009 LA Avoyelles Western Gulf

22011 LA Beauregard Western Gulf

22013 LA Bienville Louisiana-Mississippi Salt Basins

22015 LA Bossier Louisiana-Mississippi Salt Basins

22017 LA Caddo Louisiana-Mississippi Salt Basins

22019 LA Calcasieu Western Gulf

22021 LA Caldwell Louisiana-Mississippi Salt Basins

22023 LA Cameron Western Gulf

22025 LA Catahoula Louisiana-Mississippi Salt Basins

22027 LA Claiborne Louisiana-Mississippi Salt Basins

22029 LA Concordia Louisiana-Mississippi Salt BasinsDecember 2012



### A-6

FIPS Code State County Basin

22031 LA De Soto Louisiana-Mississippi Salt Basins

22033 LA East Baton Rouge Western Gulf

22035 LA East Carroll Louisiana-Mississippi Salt Basins

22037 LA East Feliciana Western Gulf

22039 LA Evangeline Western Gulf

22041 LA Franklin Louisiana-Mississippi Salt Basins

22043 LA Grant Louisiana-Mississippi Salt Basins

22045 LA Iberia Western Gulf

22047 LA Iberville Western Gulf

22049 LA Jackson Louisiana-Mississippi Salt Basins

22051 LA Jefferson Western Gulf

22053 LA Jefferson Davis Western Gulf

22055 LA Lafayette Western Gulf

22057 LA Lafourche Western Gulf

22059 LA La Salle Louisiana-Mississippi Salt Basins

22061 LA Lincoln Louisiana-Mississippi Salt Basins

22063 LA Livingston Western Gulf

22065 LA Madison Louisiana-Mississippi Salt Basins

22067 LA Morehouse Louisiana-Mississippi Salt Basins

22069 LA Natchitoches Louisiana-Mississippi Salt Basins

22071 LA Orleans Western Gulf

22073 LA Ouachita Louisiana-Mississippi Salt Basins

22075 LA Plaquemines Western Gulf

22077 LA Pointe Coupee Western Gulf

22079 LA Rapides Western Gulf

22081 LA Red River Louisiana-Mississippi Salt Basins

22083 LA Richland Louisiana-Mississippi Salt Basins

22085 LA Sabine Louisiana-Mississippi Salt Basins

22087 LA St. Bernard Western Gulf

22089 LA St. Charles Western Gulf

22091 LA St. Helena Western Gulf

22093 LA St. James Western Gulf

22095 LA St. John the Baptist Western Gulf

22097 LA St. Landry Western Gulf

22099 LA St. Martin Western Gulf

22101 LA St. Mary Western Gulf

22103 LA St. Tammany Western Gulf

22105 LA Tangipahoa Western Gulf

22107 LA Tensas Louisiana-Mississippi Salt BasinsDecember 2012



### A-7

FIPS Code State County Basin

22109 LA Terrebonne Western Gulf

22111 LA Union Louisiana-Mississippi Salt Basins

22113 LA Vermilion Western Gulf

22115 LA Vernon Western Gulf

22117 LA Washington Western Gulf

22119 LA Webster Louisiana-Mississippi Salt Basins

22121 LA West Baton Rouge Western Gulf

22123 LA West Carroll Louisiana-Mississippi Salt Basins

22125 LA West Feliciana Western Gulf

22127 LA Winn Louisiana-Mississippi Salt Basins

29001 MO Adair Not Assigned

29003 MO Andrew Not Assigned

29005 MO Atchison Not Assigned

29007 MO Audrain Not Assigned

29009 MO Barry Not Assigned

29011 MO Barton Not Assigned

29013 MO Bates Not Assigned

29015 MO Benton Not Assigned

29017 MO Bollinger Not Assigned

29019 MO Boone Not Assigned

29021 MO Buchanan Not Assigned

29023 MO Butler Not Assigned

29025 MO Caldwell Not Assigned

29027 MO Callaway Not Assigned

29029 MO Camden Not Assigned

29031 MO Cape Girardeau Not Assigned

29033 MO Carroll Not Assigned

29035 MO Carter Not Assigned

29037 MO Cass Not Assigned

29039 MO Cedar Not Assigned

29041 MO Chariton Not Assigned

29043 MO Christian Not Assigned

29045 MO Clark Not Assigned

29047 MO Clay Not Assigned

29049 MO Clinton Not Assigned

29051 MO Cole Not Assigned

29053 MO Cooper Not Assigned

29055 MO Crawford Not Assigned

29057 MO Dade Not Assigned

29059 MO Dallas Not AssignedDecember 2012



### A-8

FIPS Code State County Basin

29061 MO Daviess Not Assigned

29063 MO DeKalb Not Assigned

29065 MO Dent Not Assigned

29067 MO Douglas Not Assigned

29069 MO Dunklin Illinois Basin

29071 MO Franklin Not Assigned

29073 MO Gasconade Not Assigned

29075 MO Gentry Not Assigned

29077 MO Greene Not Assigned

29079 MO Grundy Not Assigned

29081 MO Harrison Not Assigned

29083 MO Henry Not Assigned

29085 MO Hickory Not Assigned

29087 MO Holt Not Assigned

29089 MO Howard Not Assigned

29091 MO Howell Not Assigned

29093 MO Iron Not Assigned

29095 MO Jackson Not Assigned

29097 MO Jasper Not Assigned

29099 MO Jefferson Not Assigned

29101 MO Johnson Not Assigned

29103 MO Knox Not Assigned

29105 MO Laclede Not Assigned

29107 MO Lafayette Not Assigned

29109 MO Lawrence Not Assigned

29111 MO Lewis Not Assigned

29113 MO Lincoln Not Assigned

29115 MO Linn Not Assigned

29117 MO Livingston Not Assigned

29119 MO McDonald Not Assigned

29121 MO Macon Not Assigned

29123 MO Madison Not Assigned

29125 MO Maries Not Assigned

29127 MO Marion Not Assigned

29129 MO Mercer Not Assigned

29131 MO Miller Not Assigned

29133 MO Mississippi Not Assigned

29135 MO Moniteau Not Assigned

29137 MO Monroe Not Assigned

29139 MO Montgomery Not AssignedDecember 2012



### A-9

FIPS Code State County Basin

29141 MO Morgan Not Assigned

29143 MO New Madrid Not Assigned

29145 MO Newton Not Assigned

29147 MO Nodaway Not Assigned

29149 MO Oregon Not Assigned

29151 MO Osage Not Assigned

29153 MO Ozark Not Assigned

29155 MO Pemiscot Not Assigned

29157 MO Perry Not Assigned

29159 MO Pettis Not Assigned

29161 MO Phelps Not Assigned

29163 MO Pike Not Assigned

29165 MO Platte Not Assigned

29167 MO Polk Not Assigned

29169 MO Pulaski Not Assigned

29171 MO Putnam Not Assigned

29173 MO Ralls Not Assigned

29175 MO Randolph Not Assigned

29177 MO Ray Not Assigned

29179 MO Reynolds Not Assigned

29181 MO Ripley Not Assigned

29183 MO St. Charles Not Assigned

29185 MO St. Clair Not Assigned

29186 MO Ste. Genevieve Not Assigned

29187 MO St. Francois Not Assigned

29189 MO St. Louis Not Assigned

29193 MO Ste. Genevieve Not Assigned

29195 MO Saline Not Assigned

29197 MO Schuyler Not Assigned

29199 MO Scotland Not Assigned

29201 MO Scott Not Assigned

29203 MO Shannon Not Assigned

29205 MO Shelby Not Assigned

29207 MO Stoddard Not Assigned

29209 MO Stone Not Assigned

29211 MO Sullivan Not Assigned

29213 MO Taney Not Assigned

29215 MO Texas Not Assigned

29217 MO Vernon Not Assigned

29219 MO Warren Not AssignedDecember 2012



### A-10

FIPS Code State County Basin

29221 MO Washington Not Assigned

29223 MO Wayne Not Assigned

29225 MO Webster Not Assigned

29227 MO Worth Not Assigned

29229 MO Wright Not Assigned

29510 MO St. Louis city Not Assigned

31001 NE Adams Salina Basin

31003 NE Antelope Salina Basin

31005 NE Arthur Cambridge Arch-Central Kansas Uplift

31007 NE Banner Denver Basin

31009 NE Blaine Salina Basin

31011 NE Boone Salina Basin

31013 NE Box Butte Denver Basin

31015 NE Boyd Salina Basin

31017 NE Brown Salina Basin

31019 NE Buffalo Salina Basin

31021 NE Burt Salina Basin

31023 NE Butler Salina Basin

31025 NE Cass Nemaha Uplift

31027 NE Cedar Salina Basin

31029 NE Chase Cambridge Arch-Central Kansas Uplift

31031 NE Cherry Cambridge Arch-Central Kansas Uplift

31033 NE Cheyenne Denver Basin

31035 NE Clay Salina Basin

31037 NE Colfax Salina Basin

31039 NE Cuming Salina Basin

31041 NE Custer Salina Basin

31043 NE Dakota Salina Basin

31045 NE Dawes Denver Basin

31047 NE Dawson Cambridge Arch-Central Kansas Uplift

31049 NE Deuel Denver Basin

31051 NE Dixon Salina Basin

31053 NE Dodge Salina Basin

31055 NE Douglas Nemaha Uplift

31057 NE Dundy Cambridge Arch-Central Kansas Uplift

31059 NE Fillmore Salina Basin

31061 NE Franklin Salina Basin

31063 NE Frontier Cambridge Arch-Central Kansas Uplift

31065 NE Furnas Cambridge Arch-Central Kansas Uplift

31067 NE Gage Nemaha UpliftDecember 2012



### A-11

FIPS Code State County Basin

31069 NE Garden Denver Basin

31071 NE Garfield Salina Basin

31073 NE Gosper Cambridge Arch-Central Kansas Uplift

31075 NE Grant Cambridge Arch-Central Kansas Uplift

31077 NE Greeley Salina Basin

31079 NE Hall Salina Basin

31081 NE Hamilton Salina Basin

31083 NE Harlan Salina Basin

31085 NE Hayes Cambridge Arch-Central Kansas Uplift

31087 NE Hitchcock Cambridge Arch-Central Kansas Uplift

31089 NE Holt Salina Basin

31091 NE Hooker Cambridge Arch-Central Kansas Uplift

31093 NE Howard Salina Basin

31095 NE Jefferson Salina Basin

31097 NE Johnson Nemaha Uplift

31099 NE Kearney Salina Basin

31101 NE Keith Cambridge Arch-Central Kansas Uplift

31103 NE Keya Paha Salina Basin

31105 NE Kimball Denver Basin

31107 NE Knox Salina Basin

31109 NE Lancaster Salina Basin

31111 NE Lincoln Cambridge Arch-Central Kansas Uplift

31113 NE Logan Cambridge Arch-Central Kansas Uplift

31115 NE Loup Salina Basin

31117 NE McPherson Cambridge Arch-Central Kansas Uplift

31119 NE Madison Salina Basin

31121 NE Merrick Salina Basin

31123 NE Morrill Denver Basin

31125 NE Nance Salina Basin

31127 NE Nemaha Forest City Basin

31129 NE Nuckolls Salina Basin

31131 NE Otoe Nemaha Uplift

31133 NE Pawnee Nemaha Uplift

31135 NE Perkins Cambridge Arch-Central Kansas Uplift

31137 NE Phelps Salina Basin

31139 NE Pierce Salina Basin

31141 NE Platte Salina Basin

31143 NE Polk Salina Basin

31145 NE Red Willow Cambridge Arch-Central Kansas Uplift

31147 NE Richardson Forest City BasinDecember 2012



### A-12

FIPS Code State County Basin

31149 NE Rock Salina Basin

31151 NE Saline Salina Basin

31153 NE Sarpy Nemaha Uplift

31155 NE Saunders Salina Basin

31157 NE Scotts Bluff Denver Basin

31159 NE Seward Salina Basin

31161 NE Sheridan Denver Basin

31163 NE Sherman Salina Basin

31165 NE Sioux Denver Basin

31167 NE Stanton Salina Basin

31169 NE Thayer Salina Basin

31171 NE Thomas Cambridge Arch-Central Kansas Uplift

31173 NE Thurston Salina Basin

31175 NE Valley Salina Basin

31177 NE Washington Salina Basin

31179 NE Wayne Salina Basin

31181 NE Webster Salina Basin

31183 NE Wheeler Salina Basin

31185 NE York Salina Basin

40001 OK Adair Cherokee Platform

40003 OK Alfalfa Anadarko Basin

40005 OK Atoka Arkoma Basin

40007 OK Beaver Anadarko Basin

40009 OK Beckham Anadarko Basin

40011 OK Blaine Anadarko Basin

40013 OK Bryan Arkoma Basin

40015 OK Caddo Anadarko Basin

40017 OK Canadian Anadarko Basin

40019 OK Carter Southern Oklahoma

40021 OK Cherokee Cherokee Platform

40023 OK Choctaw Arkoma Basin

40025 OK Cimarron Palo Duro Basin

40027 OK Cleveland Nemaha Uplift

40029 OK Coal Arkoma Basin

40031 OK Comanche Southern Oklahoma

40033 OK Cotton Southern Oklahoma

40035 OK Craig Cherokee Platform

40037 OK Creek Cherokee Platform

40039 OK Custer Anadarko Basin

40041 OK Delaware Cherokee PlatformDecember 2012



### A-13

FIPS Code State County Basin

40043 OK Dewey Anadarko Basin

40045 OK Ellis Anadarko Basin

40047 OK Garfield Anadarko Basin

40049 OK Garvin Southern Oklahoma

40051 OK Grady Anadarko Basin

40053 OK Grant Anadarko Basin

40055 OK Greer Anadarko Basin

40057 OK Harmon Bend Arch-Fort Worth Basin

40059 OK Harper Anadarko Basin

40061 OK Haskell Arkoma Basin

40063 OK Hughes Arkoma Basin

40065 OK Jackson Bend Arch-Fort Worth Basin

40067 OK Jefferson Southern Oklahoma

40069 OK Johnston Southern Oklahoma

40071 OK Kay Nemaha Uplift

40073 OK Kingfisher Anadarko Basin

40075 OK Kiowa Anadarko Basin

40077 OK Latimer Arkoma Basin

40079 OK Le Flore Arkoma Basin

40081 OK Lincoln Cherokee Platform

40083 OK Logan Nemaha Uplift

40085 OK Love Southern Oklahoma

40087 OK McClain Nemaha Uplift

40089 OK McCurtain Arkoma Basin

40091 OK McIntosh Arkoma Basin

40093 OK Major Anadarko Basin

40095 OK Marshall Southern Oklahoma

40097 OK Mayes Cherokee Platform

40099 OK Murray Southern Oklahoma

40101 OK Muskogee Cherokee Platform

40103 OK Noble Nemaha Uplift

40105 OK Nowata Cherokee Platform

40107 OK Okfuskee Cherokee Platform

40109 OK Oklahoma Nemaha Uplift

40111 OK Okmulgee Cherokee Platform

40113 OK Osage Cherokee Platform

40115 OK Ottawa Cherokee Platform

40117 OK Pawnee Cherokee Platform

40119 OK Payne Cherokee Platform

40121 OK Pittsburg Arkoma BasinDecember 2012



### A-14

FIPS Code State County Basin

40123 OK Pontotoc Arkoma Basin

40125 OK Pottawatomie Cherokee Platform

40127 OK Pushmataha Arkoma Basin

40129 OK Roger Mills Anadarko Basin

40131 OK Rogers Cherokee Platform

40133 OK Seminole Cherokee Platform

40135 OK Sequoyah Arkoma Basin

40137 OK Stephens Southern Oklahoma

40139 OK Texas Anadarko Basin

40141 OK Tillman Bend Arch-Fort Worth Basin

40143 OK Tulsa Cherokee Platform

40145 OK Wagoner Cherokee Platform

40147 OK Washington Cherokee Platform

40149 OK Washita Anadarko Basin

40151 OK Woods Anadarko Basin

40153 OK Woodward Anadarko Basin

48001 TX Anderson East Texas Basin

48003 TX Andrews Permian Basin

48005 TX Angelina East Texas Basin

48007 TX Aransas Western Gulf

48009 TX Archer Bend Arch-Fort Worth Basin

48011 TX Armstrong Palo Duro Basin

48013 TX Atascosa Western Gulf

48015 TX Austin Western Gulf

48017 TX Bailey Palo Duro Basin

48019 TX Bandera Bend Arch-Fort Worth Basin

48021 TX Bastrop Western Gulf

48023 TX Baylor Bend Arch-Fort Worth Basin

48025 TX Bee Western Gulf

48027 TX Bell Western Gulf

48029 TX Bexar Western Gulf

48031 TX Blanco Bend Arch-Fort Worth Basin

48033 TX Borden Permian Basin

48035 TX Bosque Bend Arch-Fort Worth Basin

48037 TX Bowie East Texas Basin

48039 TX Brazoria Western Gulf

48041 TX Brazos Western Gulf

48043 TX Brewster Marathon Thrust Belt

48045 TX Briscoe Palo Duro Basin

48047 TX Brooks Western GulfDecember 2012



### A-15

FIPS Code State County Basin

48049 TX Brown Bend Arch-Fort Worth Basin

48051 TX Burleson Western Gulf

48053 TX Burnet Bend Arch-Fort Worth Basin

48055 TX Caldwell Western Gulf

48057 TX Calhoun Western Gulf

48059 TX Callahan Bend Arch-Fort Worth Basin

48061 TX Cameron Western Gulf

48063 TX Camp East Texas Basin

48065 TX Carson Anadarko Basin

48067 TX Cass East Texas Basin

48069 TX Castro Palo Duro Basin

48071 TX Chambers Western Gulf

48073 TX Cherokee East Texas Basin

48075 TX Childress Palo Duro Basin

48077 TX Clay Bend Arch-Fort Worth Basin

48079 TX Cochran Permian Basin

48081 TX Coke Permian Basin

48083 TX Coleman Bend Arch-Fort Worth Basin

48085 TX Collin Bend Arch-Fort Worth Basin

48087 TX Collingsworth Palo Duro Basin

48089 TX Colorado Western Gulf

48091 TX Comal Western Gulf

48093 TX Comanche Bend Arch-Fort Worth Basin

48095 TX Concho Bend Arch-Fort Worth Basin

48097 TX Cooke Bend Arch-Fort Worth Basin

48099 TX Coryell Bend Arch-Fort Worth Basin

48101 TX Cottle Palo Duro Basin

48103 TX Crane Permian Basin

48105 TX Crockett Permian Basin

48107 TX Crosby Permian Basin

48109 TX Culberson Permian Basin

48111 TX Dallam Palo Duro Basin

48113 TX Dallas Bend Arch-Fort Worth Basin

48115 TX Dawson Permian Basin

48117 TX Deaf Smith Palo Duro Basin

48119 TX Delta East Texas Basin

48121 TX Denton Bend Arch-Fort Worth Basin

48123 TX DeWitt Western Gulf

48125 TX Dickens Permian Basin

48127 TX Dimmit Western GulfDecember 2012



### A-16

FIPS Code State County Basin

48129 TX Donley Palo Duro Basin

48131 TX Duval Western Gulf

48133 TX Eastland Bend Arch-Fort Worth Basin

48135 TX Ector Permian Basin

48137 TX Edwards Permian Basin

48139 TX Ellis Bend Arch-Fort Worth Basin

48141 TX El Paso Permian Basin

48143 TX Erath Bend Arch-Fort Worth Basin

48145 TX Falls East Texas Basin

48147 TX Fannin East Texas Basin

48149 TX Fayette Western Gulf

48151 TX Fisher Permian Basin

48153 TX Floyd Palo Duro Basin

48155 TX Foard Bend Arch-Fort Worth Basin

48157 TX Fort Bend Western Gulf

48159 TX Franklin East Texas Basin

48161 TX Freestone East Texas Basin

48163 TX Frio Western Gulf

48165 TX Gaines Permian Basin

48167 TX Galveston Western Gulf

48169 TX Garza Permian Basin

48171 TX Gillespie Bend Arch-Fort Worth Basin

48173 TX Glasscock Permian Basin

48175 TX Goliad Western Gulf

48177 TX Gonzales Western Gulf

48179 TX Gray Anadarko Basin

48181 TX Grayson Bend Arch-Fort Worth Basin

48183 TX Gregg East Texas Basin

48185 TX Grimes Western Gulf

48187 TX Guadalupe Western Gulf

48189 TX Hale Palo Duro Basin

48191 TX Hall Palo Duro Basin

48193 TX Hamilton Bend Arch-Fort Worth Basin

48195 TX Hansford Anadarko Basin

48197 TX Hardeman Bend Arch-Fort Worth Basin

48199 TX Hardin Western Gulf

48201 TX Harris Western Gulf

48203 TX Harrison East Texas Basin

48205 TX Hartley Palo Duro Basin

48207 TX Haskell Bend Arch-Fort Worth BasinDecember 2012



### A-17

FIPS Code State County Basin

48209 TX Hays Western Gulf

48211 TX Hemphill Anadarko Basin

48213 TX Henderson East Texas Basin

48215 TX Hidalgo Western Gulf

48217 TX Hill Bend Arch-Fort Worth Basin

48219 TX Hockley Permian Basin

48221 TX Hood Bend Arch-Fort Worth Basin

48223 TX Hopkins East Texas Basin

48225 TX Houston East Texas Basin

48227 TX Howard Permian Basin

48229 TX Hudspeth Permian Basin

48231 TX Hunt East Texas Basin

48233 TX Hutchinson Anadarko Basin

48235 TX Irion Permian Basin

48237 TX Jack Bend Arch-Fort Worth Basin

48239 TX Jackson Western Gulf

48241 TX Jasper Western Gulf

48243 TX Jeff Davis Permian Basin

48245 TX Jefferson Western Gulf

48247 TX Jim Hogg Western Gulf

48249 TX Jim Wells Western Gulf

48251 TX Johnson Bend Arch-Fort Worth Basin

48253 TX Jones Bend Arch-Fort Worth Basin

48255 TX Karnes Western Gulf

48257 TX Kaufman East Texas Basin

48259 TX Kendall Bend Arch-Fort Worth Basin

48261 TX Kenedy Western Gulf

48263 TX Kent Permian Basin

48265 TX Kerr Bend Arch-Fort Worth Basin

48267 TX Kimble Bend Arch-Fort Worth Basin

48269 TX King Permian Basin

48271 TX Kinney Western Gulf

48273 TX Kleberg Western Gulf

48275 TX Knox Bend Arch-Fort Worth Basin

48277 TX Lamar East Texas Basin

48279 TX Lamb Palo Duro Basin

48281 TX Lampasas Bend Arch-Fort Worth Basin

48283 TX La Salle Western Gulf

48285 TX Lavaca Western Gulf

48287 TX Lee Western GulfDecember 2012



### A-18

FIPS Code State County Basin

48289 TX Leon East Texas Basin

48291 TX Liberty Western Gulf

48293 TX Limestone East Texas Basin

48295 TX Lipscomb Anadarko Basin

48297 TX Live Oak Western Gulf

48299 TX Llano Bend Arch-Fort Worth Basin

48301 TX Loving Permian Basin

48303 TX Lubbock Permian Basin

48305 TX Lynn Permian Basin

48307 TX McCulloch Bend Arch-Fort Worth Basin

48309 TX McLennan Bend Arch-Fort Worth Basin

48311 TX McMullen Western Gulf

48313 TX Madison Western Gulf

48315 TX Marion East Texas Basin

48317 TX Martin Permian Basin

48319 TX Mason Bend Arch-Fort Worth Basin

48321 TX Matagorda Western Gulf

48323 TX Maverick Western Gulf

48325 TX Medina Western Gulf

48327 TX Menard Bend Arch-Fort Worth Basin

48329 TX Midland Permian Basin

48331 TX Milam Western Gulf

48333 TX Mills Bend Arch-Fort Worth Basin

48335 TX Mitchell Permian Basin

48337 TX Montague Bend Arch-Fort Worth Basin

48339 TX Montgomery Western Gulf

48341 TX Moore Anadarko Basin

48343 TX Morris East Texas Basin

48345 TX Motley Palo Duro Basin

48347 TX Nacogdoches East Texas Basin

48349 TX Navarro East Texas Basin

48351 TX Newton Western Gulf

48353 TX Nolan Permian Basin

48355 TX Nueces Western Gulf

48357 TX Ochiltree Anadarko Basin

48359 TX Oldham Palo Duro Basin

48361 TX Orange Western Gulf

48363 TX Palo Pinto Bend Arch-Fort Worth Basin

48365 TX Panola East Texas Basin

48367 TX Parker Bend Arch-Fort Worth BasinDecember 2012



### A-19

FIPS Code State County Basin

48369 TX Parmer Palo Duro Basin

48371 TX Pecos Permian Basin

48373 TX Polk Western Gulf

48375 TX Potter Palo Duro Basin

48377 TX Presidio Permian Basin

48379 TX Rains East Texas Basin

48381 TX Randall Palo Duro Basin

48383 TX Reagan Permian Basin

48385 TX Real Bend Arch-Fort Worth Basin

48387 TX Red River East Texas Basin

48389 TX Reeves Permian Basin

48391 TX Refugio Western Gulf

48393 TX Roberts Anadarko Basin

48395 TX Robertson East Texas Basin

48397 TX Rockwall East Texas Basin

48399 TX Runnels Bend Arch-Fort Worth Basin

48401 TX Rusk East Texas Basin

48403 TX Sabine East Texas Basin

48405 TX San Augustine East Texas Basin

48407 TX San Jacinto Western Gulf

48409 TX San Patricio Western Gulf

48411 TX San Saba Bend Arch-Fort Worth Basin

48413 TX Schleicher Permian Basin

48415 TX Scurry Permian Basin

48417 TX Shackelford Bend Arch-Fort Worth Basin

48419 TX Shelby East Texas Basin

48421 TX Sherman Anadarko Basin

48423 TX Smith East Texas Basin

48425 TX Somervell Bend Arch-Fort Worth Basin

48427 TX Starr Western Gulf

48429 TX Stephens Bend Arch-Fort Worth Basin

48431 TX Sterling Permian Basin

48433 TX Stonewall Permian Basin

48435 TX Sutton Permian Basin

48437 TX Swisher Palo Duro Basin

48439 TX Tarrant Bend Arch-Fort Worth Basin

48441 TX Taylor Bend Arch-Fort Worth Basin

48443 TX Terrell Marathon Thrust Belt

48445 TX Terry Permian Basin

48447 TX Throckmorton Bend Arch-Fort Worth BasinDecember 2012



### A-20

FIPS Code State County Basin

48449 TX Titus East Texas Basin

48451 TX Tom Green Permian Basin

48453 TX Travis Western Gulf

48455 TX Trinity Western Gulf

48457 TX Tyler Western Gulf

48459 TX Upshur East Texas Basin

48461 TX Upton Permian Basin

48463 TX Uvalde Western Gulf

48465 TX Val Verde Permian Basin

48467 TX Van Zandt East Texas Basin

48469 TX Victoria Western Gulf

48471 TX Walker Western Gulf

48473 TX Waller Western Gulf

48475 TX Ward Permian Basin

48477 TX Washington Western Gulf

48479 TX Webb Western Gulf

48481 TX Wharton Western Gulf

48483 TX Wheeler Anadarko Basin

48485 TX Wichita Bend Arch-Fort Worth Basin

48487 TX Wilbarger Bend Arch-Fort Worth Basin

48489 TX Willacy Western Gulf

48491 TX Williamson Western Gulf

48493 TX Wilson Western Gulf

48495 TX Winkler Permian Basin

48497 TX Wise Bend Arch-Fort Worth Basin

48499 TX Wood East Texas Basin

48501 TX Yoakum Permian Basin

48503 TX Young Bend Arch-Fort Worth Basin

48505 TX Zapata Western Gulf

48507 TX Zavala Western GulfDecember 2012



## APPENDIX B

Field Names for Production Data from HPDIDecember 2012



### B-1



## Appendix B: Field Names for Production Data from HP DI

Area source categories in the current inventory wer e assigned source classification code(s) (SCC) that best described the emissions source anal yzed. The SCCs designation aids in the

submission of emissions for the NEI. Some source ca tegories are characterized by more than one SCC and thus emissions were estimated separatel y to fit an SCC description. Often source categories will be independently estimated by well type (gas versus oil), thus resulting in two SCCs for similar equipment/source. Other examples i nclude wellhead and lateral compressors, as well as fugitives, which are assigned different SCCs depending on equipment characteristics.

Table B-1. Field Names and Descriptions in the Pro duction Well Table in the EPA Enforcement Universe Database (created from HPDI).

Field Name Description

ENTITY_ID HPDI assigned unique property ID. Note: for instanc es where duplicate API numbers were combined, the minimum value was se lected.

API_NO API assigned number of a well on the property.

PROPERTY_TYPE Property type (e.g., lease, unit, well, completion, other, unknown). Note: for instances where duplicate API numbers wer e combined, the

minimum value was selected.

PRODUCTION_TYPE Production type (e.g., oil, gas, coalbed methane, i njection). Note: for instances where duplicate API numbers were combined , the production type fields are comma separated.

WELL_NAME Operator assigned well/lease name of the property. Note: for instances where duplicate API numbers were combined, the mini mum value was

selected.

LEASE_NO State number assigned to the property or lease or u nit the property is part of. Note: for instances where duplicate API nu mbers were combined, the minimum value was selected.

WELL_NO Operator assigned well number of the property. Note : for instances where duplicate API numbers were combined, the mini mum value was

selected.

CURR_OPER_NAME Current operator name. Note: for instances where du plicate API numbers were combined, the minimum value was select ed.

LIQ_GATH_NAME_1 Current primary liquid gatherer for a property. Not e: for instances where duplicate API numbers were combined, the prod uction type fields are comma separated.

GAS_GATH_NAME_1 Current primary gas gatherer for a property. Note: for instances where duplicate API numbers were combined, the production type fields are comma separated.

COMMON_OPER_NAME Corporate entity that is determined by HPDI to own the current operator. Note: for instances where duplicate API n umbers were combined, the minimum value was selected.December 2012



### B-2 Field Name Description

LATITUDE Surface latitude the property is located in; for mu lti-well properties HPDI picked a well to designate the location of the property. Note: for instances where duplicate API numbers were combined , the minimum

value was selected.

LONGITUDE Surface longitude the property is located in; for m ulti-well properties HPDI picked a well to designate the location of the property. Note: for instances where duplicate API numbers were combined , the minimum

value was selected.

LATITUDE_BOTM Bottom hole latitude of the property; for multi-wel l properties HPDI picked a well to designate the location of the prop erty. Note: for instances where duplicate API numbers were combined , the minimum

value was selected.

LONGITUDE_BOTM Bottom hole longitude of the property; for multi-we ll properties HPDI picked a well to designate the location of the prop erty. Note: for instances where duplicate API numbers were combined , the minimum

value was selected.

LOCATION Township range of property. Note: for instances whe re duplicate API numbers were combined, the minimum value was select ed.

COUNTY County the property is located in. Note: for instan ces where duplicate API numbers were combined, the minimum value was se lected.

DISTRICT District within a given state the property is assig ned. Note: for instances where duplicate API numbers were combined, the mini mum value was

selected.

STATE State the property is located in. Note: for instanc es where duplicate API numbers were combined, the minimum value was select ed.

SECTION Section property is located in. Note: for instances where duplicate API numbers were combined, the minimum value was select ed.

QTR_QTR Quarter-quarter the property is located in (note: T exas only). Note: for instances where duplicate API numbers were combined , the minimum

value was selected.

MERID Meridian legal description is referenced from. Note : for instances where duplicate API numbers were combined, the mini mum value was

selected.

OFFSHORE Offshore waters indicator. Note: for instances wher e duplicate API numbers were combined, the minimum value was select ed.

FIELD Field name the property is reporting from. Note: fo r instances where duplicate API numbers were combined, the minimum va lue was

selected.

RESERVOIR Reservoir, formation, zone, or pool that the propert y is reported as producing from. Note: for instances where duplicate API numbers were combined, the minimum value was selected.December 2012



### B-3 Field Name Description

FORMATION Formation that the property is reported as producin g from. Note: for instances where duplicate API numbers were combined , the minimum

value was selected.

BASIN Basin the property is located in. Note: for instanc es where duplicate API numbers were combined, the minimum value was select ed.

STATUS Current status of the well (e.g., active, inactive, shut in). See Error!

Reference source not found. for the status codes and descriptions. Note: for instances where duplicate API numbers wer e combined, the

minimum value was selected.

SPUD_DATE Latest date drilling commenced on property. Note: f or instances where duplicate API numbers were combined, the minimum va lue was

selected.

DRILL_TYPE Drill type (e.g., horizontal, vertical, directional ). See Error! Reference

source not found. for the drill type codes and descriptions. Note: f or instances where duplicate API numbers were combined , the minimum

value was selected.

COMPLETION_DATE Latest completion date of the property. Note: for i nstances where duplicate API numbers were combined, the minimum va lue was

selected.

TOTAL_DEPTH Total depth the property was drilled to. Note: for instances where duplicate API numbers were combined, the minimum va lue was

selected.

LAST_PROD_DATE Last date HPDI has reported production for the prop erty. Note: Even though the date may be represented as mm/dd/yyyy, i t is for the month listed, not just the individual day. For exam ple, production through December 2009 is listed as 12/1/2009.

LATEST_FLOW_

PRESSURE Latest flow pressure reported. Note: for instances where duplicate API numbers were combined, the minimum value was select ed.

LATEST_WHSIP Latest well head shut-in pressure reported. Note: f or instances where duplicate API numbers were combined, the minimum va lue was

selected.

SumOfLIQ_DAILY Average daily liquid production in last 12 months, summed over duplicate API numbers.

SumOfGAS_DAILY Average daily gas production in last 12 months, sum med over duplicate

API numbers.

SumOfLIQ_CUM Cumulative liquid production of property, reported in bbl, summed over duplicate API numbers.

SumOfGAS_CUM Cumulative gas production of property, reported in MCF, summed over duplicate API numbers.

SumOfWRT_CUM Cumulative water production of property, summed ove r duplicate API

numbers.December 2012



### B-4 Field Name Description

SumOfLIQ_YEAR Liquid production, reported in bbls, for the 12 mon ths ending with LAST_PROD_DATE, summed over duplicate API numbers.

SumOfGAS_YEAR Gas production, reported in MCF, for the 12 months ending with LAST_PROD_DATE, summed over duplicate API numbers.

SumOfWTR_YEAR Water production, reported in bbls, for the 12 mont hs ending with LAST_PROD_DATE, summed over duplicate API numbers.

SumOfLIQ07 Liquid production, reported in bbls, for 2007, summ ed over duplicate

API numbers.

SumOfGAS07 Gas production, reported in MCF, for 2007, summed o ver duplicate API

numbers.

SumOfWTR07 Water production, reported in bbls, for 2007, summe d over duplicate

API numbers.

SumOfLIQ08 Liquid production, reported in bbls, for 2008, summ ed over duplicate

API numbers.

SumOfGAS08 Gas production, reported in MCF, for 2008, summed o ver duplicate API

numbers.

SumOfWTR08 Water production, reported in bbls, for 2008, summe d over duplicate

API numbers.

SumOfLIQ09 Liquid production, reported in bbls, for 2009, summ ed over duplicate

API numbers.

SumOfGAS09 Gas production, reported in MCF, for 2009, summed o ver duplicate API

numbers.

SumOfWTR09 Water production, reported in bbls, for 2009, summe d over duplicate

API numbers.

SumOfLIQ10 Liquid production, reported in bbls, for 2010, summ ed over duplicate

API numbers.

SumOfGAS10 Gas production, reported in MCF, for 2010, summed o ver duplicate API

numbers.

SumOfWTR10 Water production, reported in bbls, for 2010, summe d over duplicate

API numbers.

SumOfLIQ11 Liquid production, reported in bbls, for 2011, summ ed over duplicate

API numbers.

SumOfGAS11 Gas production, reported in MCF, for 2011, summed o ver duplicate API

numbers.

SumOfWTR11 Water production, reported in bbls, for 2011, summe d over duplicate

API numbers.

SumOfLIQ12 Liquid production, reported in bbls, for 2012, summ ed over duplicate

API numbers.

SumOfGAS12 Gas production, reported in MCF, for 2012, summed o ver duplicate API

numbers.December 2012



### B-5 Field Name Description

SumOfWTR12 Water production, reported in bbls, for 2012, summe d over duplicate

API numbers.

PROD09_FLAG Yes/No flag indicating if liquid and/or gas product ion was greater than

zero in 2009.

PROD10_FLAG Yes/No flag indicating if liquid and/or gas product ion was greater than

zero in 2010.

PROD11_FLAG Yes/No flag indicating if liquid and/or gas product ion was greater than

zero in 2011.

PROD12_FLAG Yes/No flag indicating if liquid and/or gas product ion was greater than

zero in 2012.

ACTIVE_FLAG Yes/No flag indicating active status based on lates t production date.

ACTIVE_PROD_FLAG Yes/No flag indicating whether entity produced liqu id and/or gas in 2009-2012, using the production flags.

SHALE_FLAG Yes/No flag for Pennsylvania only indicating if the type of production is shale gas.

INITIAL_OIL Initial oil production. Note: Only for Indiana and Illinois.

INITIAL_GAS Initial gas production. Note: Only for Indiana and Illinois.

INITIAL_WATER Initial water production. Note: Only for Indiana an d Illinois.

TEST_DATE Date of the most recent well test.

TEST_TIMES_TESTED Total number of times the well was tested.

TEST_GAS_CUM Cumulative reported gas at the time of the most rec ent well test.

TEST_GOR Gas to oil ratio at the time of the most recent wel l test.

TEST_FLOW_PRES Well head flowing pressure at the time of the most recent well test.

TEST_FLOWOZ Flowing pressure divided by Z-Factor at the time of the most recent well

test.

TEST_WHSIP Well head shut-in pressure at the time of the most recent well test.

TEST_SIPOZ Bottom hole pressure divided by the Z-Factor, if we ll head shut-in pressure is provided at the time of the most recent well test.

TEST_GAS_GRAVITY Gas gravity at the time of the most recent well tes t.

TEST_LIQ_GRAVITY Liquid gravity at the time of the most recent well test.

TEST_GAS_VOLUME Daily gas production at the time of the most recent well test.

TEST_LIQ_VOLUME Daily water production at the time of the most rece nt well test.

TEST_WAT_VOLUME Daily liquid production at the time of the most rec ent well test.

TEST_TYPE Type of test conducted for the most recent well tes t.

TEST_CHOKE_SIZE Choke used during the most recent well test.

TEST_TBG_PRES Pressure present in the tubing at the time of the m ost recent well test.

HUC12_CODE EPA populated field.

Indian_Lands EPA populated field.December 2012



### B-6 Field Name Description

Federal_Lands EPA populated field.

Percent_Minority EPA populated field.

Sole_Source_Aquifer EPA populated field.

Water_Protection_Area EPA populated field.

NA_Pollution_Code EPA populated field.December 2012



## APPENDIX C

Electronic Appendix: Industry survey forms (Excel W orkbooks)December 2012



## APPENDIX D

Electronic Appendix: CenSARA Emissions Calculator T ools (Excel Workbooks)