# Oil and Natural Gas Sector

Hydraulically Fractured Oil Well Completions and Associated Gas during

Ongoing Production

R ep o r t f o r O il and N atural G as Sector Oil Well Completions and Associated Gas during Ongoing Production R e v i ew P a n e l April 2014

P r e p a r e d by

U

. S. E PA O f

f i c e o f A i r Q u a l i t y P l a nn i ng a n d S t a n d a r ds ( O A Q PS)

T h i s i n f or m a ti on i s d

i s t r i b u t e d so l e l y f or t h e p u rpose of pr e - d

i ss e m i n a ti on p ee r r

ev i e w u n d

e r a p p li c ab l e i n f or m a ti on q u a lit

y g u i d e li ne s. I t h as n ot b ee n f

or m a ll y d i ss e m i n a t e d by t he E P A . It do e s n ot r e

pr e s en t

a n d s h o u l

d n ot be c o n s t

r u e d t o r e pr e s en t a n y A g enc y d e t e r m i n a ti on or po li cy
.iiiii



## Table of Contents

PREFACE

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

1 .0 INTRODUCTION

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

2.0 DEFINITION OF THE SOURCE

................................ ................................ ................................ .... 3

2.1 Oil Well Completions

................................ ................................ ................................ ................... 3

2.2 Associated Gas

................................ ................................ ................................ .............................. 5

3.0 EMISSIONS DATA AND EMISSIONS ESTIMATES

– HYDRAULICALLY FRACTURED OIL WELL COMPLETIONS

................................ ................................ ................................ ....................... 5

3.1 Summary of M ajor Studies and Sources of Emissions Data

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

3.2 Fort Berthold Federal Implementation Plan (FIP)

– Analysis by EC/R (U.S. EPA) 2012a)

........ 8

3.3 ERG Inc. and EC/R Analyses of HPDI Data

................................ ................................ .............. 12

3.4 Environmental Defense Fund and Stratus Consulting Analysis of Oil Well Completions (EDF, 2014) 15

3.5 Measurements of Methane Emissions at Natural Gas Production Sites in the United States (UT Study) (Allen et al., 2013)

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

3.6 Methane Leaks from North American Natural Gas Sy stems (Brandt et. al, 2014a and 2014b)

. 18

4.0 EMISSIONS DATA AND EMISSIONS ESTIMATES

– ASSOCIATED GAS FROM HYDRAULICALLY FRACTURED OIL WELLS

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

4.1 Greenhouse Gas Reporting Program (U.S. EPA, 2013)

................................ ............................. 21

4.2 FLARING UP: North Dakota Natural Gas Flaring More Than Doubles in Two Years (Flaring Up) (CERES, 2013)

................................ ................................ ................................ ................................ 22

5.0 AVAILABLE EMISSION MITIGATION TECHNIQUES

................................ ........................... 23

5.1 Reduced Emission Completions (REC)

................................ ................................ ...................... 23

5 .1.1 Description

................................ ................................ ................................ .............................. 23

5.1.2 Effectiveness

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

5.2 Completion Combustion Devices

................................ ................................ ............................... 27

5.2.1 Description

................................ ................................ ................................ .............................. 27

5.2.2 Effectiveness

................................ ................................ ................................ ........................... 27

5.3 Emerging Control Technologies for Control of Associated Gas

................................ ................ 30

5.3.1 Natural Gas Liquids (NGL) Recovery

................................ ................................ .................... 30

5.3.2 Natural Gas Reinjection

................................ ................................ ................................ .......... 35

6.0 SUMMARY

................................ ................................ ................................ ................................ .... 43iv

7.0 CHARGE QUESTIONS FOR REVIEWERS

................................ ................................ ................ 45

8.0 REFERENCES

................................ ................................ ................................ ............................... 48
Appendix A

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



## PREFACE

On March 28, 2014 the Obama Administration released a key element called for in the President’s Climate Action Plan: a Strategy to Reduce Methane Emissions. The strategy

summarizes the sources of methane emission s, commits to new steps to cut emissions of this potent greenhouse gas, and outlines the Administration’s efforts to improve the measurement of these emissions. The strategy builds on progress to date and takes steps to further cut methane

emissions from s everal sectors, including the oil and natural gas sector.

This technical white paper is one of those steps. The paper, along with four others, focuses on potentially significant sources of methane and volatile organic compounds (VOCs) in the oil and gas sector, covering emissions and mitigation techniques for both pollutants. The

A gency is seeking input from independent experts, along with data and technical information from the public. The EPA will use these technical documents to solidify our understand ing of these potentially significant sources, which will allow us to fully evaluate the range of options

for cost

- effectively cutting VOC and methane waste and emissions.

The white papers are available at: www.epa.gov/airquality/oilandgas/whitepapers.html2



## 1.0 INTRODUCTION

The oil and natural gas exploration and production industry in the U.S. is highly dynamic and growing rapidly. Consequently, the number of wells in service and the potential for greater

air emissions from oil and natural gas sources is also growing. There were an estimated 504,000 producing gas wells in the U.S. in 2011 ( U

. S

. EIA, 2012a), and an estimated 536,000 producing oil wells in the U.S. in 2011 ( U

. S

. EIA, 20 12b). I t is anticipated that the number of gas and oil

wells will continue to increa se substantially in the future because of the continued and expanding use of horizontal drilling combined with hydraulic fracturing (referred to here as simply hydraulic fr acturing) which allows for drilling in formerly inaccessible formations

.

Due to the growth of this sector and the potential for increased air emissions, it is important that the U.S. Environmental Protection Agency (EPA) obtain a clear and accurate

under standing of emerging data on air emissions and available mitigation options

. This paper presents the Agency’s understanding of air emissions and available control technologies from a potentially significant source of emissions in the oil and natural gas se ctor.

Oil and gas production from unconventional formations such as shale deposits or plays has grown rapidly over the last decade. Oil and natural gas production is projected to steadily increase over the next two decades. Specifically
, natural gas devel opment is expected to increase by 44 % from 2011 through 2040 (U

. S

. EIA, 2013 b ) and crude oil and natural gas liquids (NGL) are projected to increase by approximately 25 % through 2019 (U

. S

. EIA, 2013 b )

. The projected growth of natural gas production is prim arily led by the increased development of shale gas, tight gas, and coalbed methane resources utilizing new production technology and techniques such as horizontal drilling and hydraulic fracturing. According to the U.S. Energy Information

Administration ( EIA), o ver half of new oil wells drilled co

- produce natural gas (U

. S

. EIA,

2013 a )

. Based on this increased oil and gas development, and the fact that half of new oil wells

co

- produce natural gas, the potential exists for increased air emissions from these operations.

One of the activities identified as a potential source of emissions to the atmosphere during oil development is hydraulically fractured oil well completions. Completion operations3



### are conducted to either bring a new oil well into the produc tion phase, or to maintain or increase
the well’s production capability

. Although the term “recompletion” is sometimes used to refer to completions associated with refracturing of existing wells , this paper will use the term “completion” for both newly fra ctured wells and refractured wells. In addition, hydraulically

fracture d coproducing oil wells can generate emission s of associated gas during the production phase

. These processes and emissions are described in detail in Section 2.

Th e purpose of this pa per is to summarize the EPA’s understanding of VOC and methane emissions from hydraulically fractured oil well completion s and associated gas during ongoing production . It also presents the EPA’s understanding of mitigation techniques (practices and equipm ent) available to reduce these emissions, including the efficacy and cost of the technologies and the prevalence of use in the industry.



## 2.0 DEFINITION OF THE SOURCE

2.1 Oil Well Completions

For the purposes of this paper, a well completion is defined to mean :

T he process that allows for the flowback of petroleum or natural gas from newly drilled wells to expel drilling and reservoir fluids and tests the reservoir flow characteristics, which may vent produced hydrocarbons to the atmosphere via an open pi t or tank.

C ompletion operations with hydraulic fracturing are conducted to either bring a new oil well into the production phase or to maintain or increase the well’s production capability ( sometimes referred to as a recompletion). Well completions with hydraulic fracturing include multiple steps after the well bore hole has reached the target depth. These steps include inserting and cementing

- in well casing, perforating the casing at one or more producing horizons, and often hydraulically fracturing one or more zones in the reservoir to stimulate production. Surface components, including wellheads, pumps, dehydrators, separators, tanks, and are installed as necessary for production to begin.4



### F or the purposes of this paper, hydraulic fracturing is define d to mean :

T he process of directing pressurized fluids containing any combination of water, proppant, and any added chemicals to penetrate tight formations, such as shale or coal formations, that subsequently require high rate, extended flowback to expel fracture fluids and solids during completions.

Hydraulic fracturing is one technique for improving oil and gas production where the reservoir rock is fractured with very high pressure fluid, typically a water emulsion with a
proppant (generally sand) tha t “ props open ” the fractures after fluid pressure is reduced.

Oil w ell completion s with hydraulic fracturing can result in VOC and methane emissions,

which occur when gas is vented to the atmosphere during flowback

. The e missions are a result of

the bac kflow 1 

### of the fracture fluids and reservoir gas at high volume and velocity necessary to

lift excess proppant and fluids to the surface. This comingled fluid stream (containing produced oil, natural gas and water) flows from each drilled well to a respecti ve vertical separator and

heater/ treater processing unit. Fluid may be heated to aid in separation of the oil and natural gas and produced w ater. Phase separation is the process of removing impurities from the hydrocarbon liquids and gas to meet sales deli very specifications for the oil and natural gas. Oil may go directly to a pipeline or be stored onsite for future transfer to a refinery. If infrastructure

is present, produced gas can be metered to a sales pipeline. If infrastructure is not available, the produced gas is frequently sent to combustion devices for destruction ( e.g., flar es ) or is vented to the atmosphere.

Recompletions are conducted to minimize the decline in production, to maintain production, or in some cases to increase production. When oil well recompletions using hydraulic fractur ing are performed, the practice and sources of emissions are essentially the same

as for new well completions involving hydraulic fractur ing , except that surface gas collection

1 Backflow is the phenomena created by pressure differences between zones in the borehole. If the wellbore pressure rises above the average pressure in any zone, backflow will occur (i.e., fluids will move back towards the borehole). In contrast , “flowback” is the term used in the industry to refer to the process of allowing fluids to flow from the well following a treatment, either in preparation for a subsequent phase of treatment or in preparation for cleanup and returning the well to producti on

. ( http://www.glossary.oilfield.slb.com/ )5



### equipment may already be present at the wellhead after the initial fracture. However, t he backflow velocity during refracturing will typically be too high for the normal wellhead equipment (separator, dehydrator, lease meter), while the production separator is not typically designed for separating sand.

2.2 Associated Gas

Associated gas is the term typically used for natural gas produced as a by

- product of the production of crude oil

. I ndustry publications typically refer to associated gas as g as that is co

produced with crude oil while the well is in the production phase and is vented directly to the atmosphere or is flared

. One published definition for associated gas is “g aseous hydrocarbons occurring as a free

- gas phase under original oil

- reservoir conditions of temperature and pressu re (a lso known as gas

- cap gas )

. ” 2 

### Therefore, associated gas can include gas that is produced during

flowback associated with completion activities and gas that is emitted from equipment as part of normal operations
, such as natural gas driven pneumatic con trollers and storage vessels

. However, i n this paper
, the term “associated gas emissions ” refers to :

Associated gas emissions from the production phase (i.e., exclud ing completion events and emissions from normal equipment operations ) that could be captur ed and sold rather than being flared or vented to the atmosphere if the necessary pipeline and other infrastructure were available to take the gas to market

.



## 3.0 EMISSIONS DATA AND EMISSIONS ESTIMATES

– HYDRAULICALLY FRACTURED OIL WELL COMPLETIONS

For c onsistency in the review of the various data sources and studies and t o better understand the data discussions presented below, this section presents an overview of the types of the emissions estimation process es and the data that have been used in a numbe r of studies to
estimate VOC and methane emissions from hydraulically fractured oil well completions and recompletions.

2 McGraw

- Hill Dictionary of Scientific & Technical Terms, 6E, Copyright © 2003 by the McGraw

- Hill Companies, Inc.6



### 1) For estimating source emiss i ons:

 G as produced during completions of oil wells

. E stimated

. This type of data would provide natural gas or methane production volumes for a completion. The data may be estimated using well characteristics ( e.g. , flow rate, casing diameter, and casing pressure)

and established emission factors.

 G as produced by the oil well annual ly / daily/monthly

. Direct measu re or estimated

. This type of data would be similar to the gas produced during completions but would be related to ongoing production of associated gas from the well.

 Gas composition . This data is typically composition results from laboratory analysis of

t he raw gas stream to determine methane and other hydrocarbon volume or weight percent for use in converting natural gas or methane emissions estimates to VOC

.

 Duration of completion cycle . Length of the completion process in days.

 Use of control technolog y

. F lares, reduced emissions completions ( RECs )
, other control technology or none . This information indicate s whether a control device or practice is

used and
, if possible, the amount of produced gas capture d and controlled

. 2) For estimating nationwide emiss ions :

 Number of oil well completions conducted annually . This information require s identification of the number of oil wells conducting completions/recompletions annually.

 Number of oil wells co

- producing natural gas . This involves identifying the populat ion of oil wells using a definition of oil well based on some production criteria.

 Number of oil wells completions with emissions controls such as RECs or flaring.

T here are several available data sources for the data elements described above. Because

mos t of the available data were not collected specifically for the purpose of estimating emissions
, each source has to be qualified to en sure that the data are being used appropriately. In

c h aracterizing the nationwide emissions
, we analyzed several sources o f data and qualify each source with respect to the different aspects of the emission estimat ion process. Therefore, in addition to describing the data source and any relevant results of analysis, this paper discusses the implications of the data and/or res ults of analysis of the data with respect to the quantity of data, quantity of emissions, scope of emissions estimates
, geographic dispersion
, and variability

in data.7



### Lastly, methodolog ies used in the emission estimation process are described , such as a discussion of the methodology for deriving emission factors or for identifying national populations.

T here is variation in the industry as to how oil wells and gas wells are defined. Some publications do not differentiate at all between them
, while other s use the amount of oil produced

or a gas

- to

- oil ratio (GOR) threshold as a dividing line between a gas well and an oil well

. This paper does not attempt to choose a specific definition of “oil well,” but instead describes the

definition s used in each stud y or data source. The intent of this section of the paper is to present
the EPA’s understanding of the available data and its usefulness in estimating VOC and methane

emission s from this source.

3.1 Summary of Major Studies and Sources of Emissions Data

Given the potential for emissions from hydraulically fractured oil well completions , there

have been several information collection efforts and studies conducted to estimate emissions and available emission control options. Studies have focused on completi on emission estimates.

Some of these studies are listed in Table 3

- 1 , along with an indication of the type of information contained in the study (i.e., activity level, emissions data, and control options).

Table 3

- 1. Summary of Major Sources of Informati on and Data on

Oil Well Completion s

Name Affiliation Year of Report Activity

Factor Uncontrolle

d/Controlled Emissions Data Control

Options Identified

Fort Berthold Federal Implementation Plan ( U.S. EPA
, 2012a ) U.S. Environmental Protection Agency 2012 Regional Uncontrolled X

ERG/ECR Contractor Analysis of HPDI® Data U.S. Environmental Protection Agency 201 3 Nationwide Uncontrolled X

Environmental Defense Fund Analysis of HPDI® Data (EDF, 2014) Environmental Defense Fund 201 4 Nationwide Uncontrolled

-8 Name Affiliation Year of Report Activity

Factor Uncontrolle

d/Controlled Emissions Data Control

Options Identified

Measurements of Methane Emissions at Natural Gas Production Sites in the United States (Allen et al

. ,

2013) Multiple Affiliations,

Academic and Private 2013 26 Completion Events Both

-

Methane Leaks from North American Natural Gas Systems ( Brandt et. al
, 2014a and 2014b ) Multiple Affiliations 2013 Regional Uncontrolled

-



### D ata for Petroleum and Natural Gas Systems collected under the EPA’s Greenhouse Gas Reporting Program (GHGRP) or the EPA’s Inventory of U.S. Greenhouse Emissions and Sinks
( GHG Invento ry), are not discussed in detail in this section . The GHGRP does not require reporting of vented emissions from hydraulically fractured oil well completions. The GHG Inventory estimates emissions from oil well completions, but does not distinguish between completions /recompletions of conventional wells and completions /recompletions of hydraulically fractured wells.

A more

- detailed description of the data sources listed in Table 3

- 1 is presented in the following sections, including how the data may be used to estimate national VOC and methane

emissions from oil well completion events.

3

. 2 Fort Berthold Federal Implementation Plan (FIP)

– Analysis by EC/R ( U.S. EPA)

2012a )

On March 22, 2013 , the EPA published (78 FR 17836) the FIP for existing, new and

modi fied oil and natural gas production facilities on the Fort Berthold Indian Reservation (FBIR). In support of that effort, t he EPA conducted an analysis of 154 applications for synthetic minor New Source Review (NSR) permits that indicated VOC emissions wer e the most prevalent of the pollutants emitted from the oil and natural gas production sources operating on
the FBIR, which contain equipment that handles natural gas produced during well completions, phase separation during production, and temporary stora ge of crude oil (U

. S

. EPA, 2012)

.9



### The EPA FIP establish ed federally enforceable requirements to control VOC emissions

f rom oil and natur al gas production activities that were previously unregulated or regulated less strictly. The FIP requires a 90%

- 98% r eduction of VOC emissions from gas not sent to a sales

line using pit flares, utility flares and enclosed combustors , all technologies which were found to be standard industry practice on the FBIR. The analysis included a large dataset of combustion

contro l equipment cost information based on three well/control configuration scenarios

.

The FBIR dataset includes :

 533 production wells from five major operators

 Average controlled and uncontrolled VOC emissions from oil well s for wellhead gas , heater/treate r s , and storage tank s

 Oil production data

 Number of sources; storage tanks, combustors, flares, and if a pipeline is present

 C urrent capital and annualized cost estimates for combustion and REC control options

 Gas composition data (for each permit applicat ion )

 Projected 2,000 new wells or 1,000 well pads per year between 2010 and 2029

.

The data provided for the FBIR, although useful, has certain qualifying limitations. For
instance, t he FBIR data is primarily for wells producing from the Bakken and Three F orks

formations
, which limits it to a regional dataset. Also, t he FBIR data showed high variability in oil well production rates and in product composition. This variability may not be representat ive

of other formations. Also, a ccording to the North Dakota Department of Health, the Bakken

formation typically contains a high amount of lighter end VOC components which have the potential to produce increased volumes of flash emissions compared to typi cal oil production

wells (U

. S

. EPA, 2012 a )

. This may be somewhat unique to the Bakken formation and not be representative nationally.

Table 3

- 2 summarizes an analysis performed by EC/R of the FBIR data with respect to oil well completion emissions. The an a lysis estimated completion emissions by multiplying the average gas volume per day for each well by a 7 day flowback period. The analysis indicated that10



### the average uncontrolled emissions from a well completion event are 37 tons of VOC per completion even t.11 

### Table 3

- 2

. Summary of FBIR FIP Oil Well Completion Uncontrolled 3 

### Casing Gas and VOC Emissions

Data from FBIR FIP

Data Element Enerplus EOG QEP c WPX b WPX

- 2 b WPX

- 3 b XTO d Marathon Petro Hunt Average Min Max
VOC Molecular weight 27.0 27.7 NA 28.1 29.6 31.7 24.5 28.5 25.8 27.8 24.5 31.7

Natural Gas Molecular weight 37.8 40.5 NA 43.7 45.9 51.0 32.9 41.4 34.3 41.0 32.9 51.0

Gas Constant (ft 3 /lbmol) a 379 379 NA 379 379 379 379 379 379 379 379.0 379

Average Oil Production (bpd)

- per well 1,181 255 NA 34 7 420 303 305 2,094 214 639.7 214 2,094

Average Gas Volume (Mcf/day)

- per well 885 182 NA 250 292 210 305 491 197 351.5 182 885

Average Gas Volume (Mcf/completion) 6,197 1,272 NA 1,748 2,042 1,473 2,133 3,439 1,378 2,460 1,272 6,197

Average Uncontrolle d VOC Emissions (ton/completion) 83 19 NA 28 37 31 23 53 16 37 16 83

NA = Not Reported, FBIR FIP = Fort Berthold Indian Reservation Federal Implementation Plan , EOG = EOG Resources , QEP = QE P Energy Co. , WPX = WPX Energy, XTO

= XTO Energy Inc.

a

- Value use d by N orth D akota f acilities represents 60 ° F and 1 atm. For s ubpart O OOO , this value is based on 68 ° F and 1 atm. b

- NOTE for WPX: i . They used three different molecular weights and percent. Therefore, each of these are represented in this table

. ii . They on ly reported 10% of the VOC emissions because they flare 90% of their casinghead gas emissions. This table represents 100 %

. c

- The QEP molecular weight and VOC content data for casinghead gas were claimed as copyrighted and were not in the online docke t

. d

- XTO reported oil production and associated gas production as the same value. Therefore, did not include this gas to oil produ ction ratio in the average.

3 Uncontrolled emissions are the emissions that would occur if no emissions mitigation practices o r technologies were used ( e.g. , completion combustion devices or RECs).12



### 3

. 3 ERG Inc. and EC / R A nalyses of HPDI D ata

ERG Inc. and EC / R (ERG/E CR) conducted an analysis of C alendar Y ear (CY) 2011

HPDI 4 

### data to estimate uncontrolled emissions from hydraulically fractured oil well completions

for the EPA

. For this analysis the following methodology was used:

ERG extracted HDPI oil well data for h ydraulically fractured, unconventional oil wells completed in CY 2011 . Because the HPDI database does not differentiate between gas and oil wells, the following criteria were used to identify th e population of hydraulically fractured oil

well completions :

 Identified wells completed in 2011 using HPDI data covering U.S. oil and natural gas wells. Summary of the data and the logic for dates used is included in the memo “ Hydraulically Fractured Oil Well Completions ” (ERG, 2013)

 Identified wells completed in 2 011 that were hydraulically fractured using the D epartment of Energy EIA formation type crosswalk supplemented with s tate data for horizontal wells (ERG, 2013)

 Determined which wells were oil wells based on their average gas

- to

- liquids ratio (less than
12, 500 scf/barrel were considered to be oil wells )

 Estimated the average daily gas flow from the cumulative natural gas production for each well during its first 12 months of production

 The resulting data set provided 192 data points representing county level average daily natural gas production at a total of 5,754 oil well completions for CY 2011

.

E missions in the ERG/ECR analysis were calculated using both a 3

- day and a 7

- day

flowback period

. The volume of natural gas emissions (in Mcf) per completion event was
calculated using the average daily flow multiplied by both a 7

- day flowback period and a 3

- day flowback period . The gas volume was converted to mass of VOC using the same VOC

4 HPDI, LLC is a private organization specializing in oil and gas data and statistical analysis. The HPDI database is focused on historical oil and gas production data and drilling per mit data. For certain states and regions, this data was supplemented by state drilling information. The 2011 data was the most current data available when the analysis was performed.13



### composition and conversion methodology used for gas wells in the s ubpart OOOO well completion evaluation. The composition values used were 46.732 % by volume of methane in natural gas and 0.8374 pound VOC per pound of methane for oil wells ( EC/R, 2011 a )

.

T he analysis of the 2011 HPDI data for oil well completions provide d an averag e gas production of 262 Mcf per well per day . Based on this gas production, the average uncontrolled

VOC emission s were 20 tons p er completion event based on a 7

- day flowback period and 6.4

tons of VOC per completion event based on a 3

- day flowback period

. The average uncontrolled

methane emission s were 24 tons p er completion event based on a 7

- day flowback period and 7.7

tons of methane per completion event based on a 3

- day flowback period. It was assumed that the emissions for an oil well recompletion eve nt are the same as an oil well completion event.

To estimate nationwide uncontrolled emissions for hydraulically fractured oil well completions, the average methane and VOC emission s per event were multiplied by the total number of estimated oil well comp letions. For 2011, which was the most recent data available in
HPDI, the estimated nationwide uncontrolled hydraulically fractured oil well completion VOC

emissions are 1 1 6,230 tons per year ( i

. e ., VOC emissions/completion of 20.2 tons/event times

the tota l oil well completion events per year of 5,274) based on a 7

- day flowback period and
36,825 tons per year (i.e., VOC emissions/completion of 6.4 tons/event times the total oil well completion events per year of 5,274) based on a 3

- day flowback period

. The estimated nationwide uncontrolled hydraulically fractured oil well completion methane emissions are 138,096 tons per year (i.e., methane emissions/completion of 24 tons/event times the total oil well completion events per year of 5,274) based on a 7

- day fl owback period and 44,306 tons per year (i.e., VOC emissions/completion of 7.7 tons/event times the total oil well completion events per year of 5,274) based on a 3

- day flowback period. Table 3

- 3 presents the results of the

emission estimate analysis for bo th the 7

- day and 3

- day completion duration periods

.14



### Table 3

- 3 . Summary of Oil Well Completion Uncontrolled Emissions from 2011 HPDI Data

7

- day event 3

- day

event

Total number of hydraulically fractured oil well completions in 2011 5,754 5,754

Number of county well production averages (data points) 195 195
Natural Gas production per well, per day, weighted average (Mcf) 262 262
Methane emissions per completion/recompletion event, weighted average (tons) 24 7.7
VOC emissions per completion/recompleti on event, weighted average (tons) 20.2 6.4
Uncontrolled Nationwide methane emissions, oil well completions (tpy) 138,096 44,306
Uncontrolled Nationwide VOC emissions, oil well completions (tpy) 116,230 36,825
Note: This estimate does not include recompl etion emissions. 

### As stated earlier, these estimates are for uncontrolled emissions, thus estimates assume no control technology applied. National

- level data on the prevalence of the use of RECs or

combustors for reduction of emissions from oil well comple tion or recompletion operations were unavailable for this analysis

.

State level information for Colorado, Texas and Wyoming on oil well recompletion

counts was used to determine a percentage of producing wells for which recompletions were reported. The s tate level data were obtained for Colorado, Texas and Wyoming for recent years ( COGCC, 2012
, Booz, 2008 and RRCTX, 2013) . Based on the state level data, it was determined that the average percentage of producing well undergoing recompletion was 0.5 % . This includes both conventional and hydraulically fractured oil wells (the data did not allow the different types of wells to be distinguished from each other). Table 3

. 4 presents a summary of this analysis.15



### Table 3

- 4 . Analysis of Texas, Wyoming and Colorad o Recompletions Counts

State Data Source Year Total Number of Producing Wells Total Number

of Recompletions Percent

Recompletions to Total Producing Wells

Railroad Commission of Texas 2012 168
, 864 685 0.4
Wyoming Heritage Foundation 2007 37
, 350 304 0.8

State of Colorado Oil & Gas Conservation Commission 2012 50
, 500 152 0.3

Average Percent 0.5



### While the state level recompletion data are recent, the percentage of producing oil wells that undergo recompletion in future years may increase due to more pre valent use of hydraulic fracturing on oil wells. However, no data have been obtained to quantify any potential increase in the oil well recompletion rate. This percentage was not used to estimate the number of recompletions of hydraulically fractured oil w ells, because the data did not distinguish between conventional wells and hydraulically fractured wells.

3. 4 Environmental Defense Fund and Stratus Consulting Analysis of Oil Well Completions 5 

### (EDF, 2014)

The Environmental Defense Fund (EDF) and Stratus C onsulting (EDF/Stratus) conducted an analysis of HPDI data for oil wells to determine the cost effectiveness of the use of REC s and

flares for control of oil well completion emissions within three major unconventional oil play formations, Bakken, Eagle For d and Wattenberg. The oil well completion population was

extracted using the DI Desktop for all oil wells with initial production in 2011 and 2012. Different filters were applied in each formation in order to identify the hydraulically fractured oil

wells:

5 This analysis is described in the EDF white paper “Co

- Producing Wells a s a Major Source of Methane Emissions: A Review of Recent Analyses” ( http://blogs.edf.org/energyexchange/files/2014/03/EDF

- Co

- producing

- Wells

Whitepaper.pd f

). It is referred to in that paper as the “EDF/Stratus Analysis.” The supplemental materials, including the data that was used in the analysis are available at https://www.dropbox.com/s/osrom4w6ewow4ua/EDF

- Initial

Production

- Cost

- Effectiveness

- Analysis.xlsx

.16



###  Eagle Ford

o Well Production Type: Oil

 Bakken

o Well Production Type: Oil and Oil & Gas

 Wattenberg

o Well Production Type: Oil

The resulting dataset included 3,694 oil wells for the Bakken formation , 1 ,797 oil wells

for the Eagle Ford formation
, and 3
, 967 oi l wells for the Wattenberg formation

. The a ssumptions

EDF /Stratus made while conducting this analysis were :

 Well completions lasted an average of 7 to 10 day s and the total gas production over that period was equal to 3 days of “Initial Gas Production” a s reported in DI Desktop (i.e., 3 days of “Initial Gas Production” was equal to the uncontrolled natural gas emissions from the oil well completion )

.

 The natural gas content was 78.8 % methane

. Table 3

- 5 summarizes the results of this analysis.

Table 3

- 5

. EDF Estimated Unco n trolled Methane Emissions from Oil Well Completions B ased on Analysis of HPDI ® Oil Well Production Data

Formation Wells (#) Uncontrolled Completion Emissions ( gas Mcf/event ) Uncontrolled

Completion Emissions ( MT CH 4 /event ) Uncontrol led

Completion Emissions ( tons CH 4 /event ) Wattenberg a 3,967 624 9.5 10.5
Bakken b 3,694 1,183 18.0 19.8 Eagle Ford c 1,797 1,628 24.7 27.2 All results represent mean values.

a

- Production data was downloaded for all oil wells in the Colorado Wattenberg formation with a first production date between 1/1/2010 and 3/1/2013. b

- Production data was downloaded for wells in the North Dakota Bakken formation with a completion date from 1/1/2010

- 12/31/2012. North Dakota does not distinguish between oil and gas wells. All wells with the type O&G were assumed to be oil wells.

c

- Production data was downloaded for all oil wells in the Texas Eagle Ford formation with a completion date between 1/1/2010 and 2/23/2013.17



### The EDF/Stratus Analysis also provided an estim ate of uncontrolled methane emissions from oil well completions of 247,000 MT (272,000 tons), however, the materials describing the analysis do not explain how this estimate was calculated.

3

. 5 Measurements of Methane Emissions at Natural Gas Production Si tes in the United

States (UT Study) ( Allen et al. , 2013)

The UT Study was p rimarily authored by University of Texas at Austin and was sponsored by the EDF and several companies in the oil and gas production industry. The study was conducted to gather m ethane emissions data at onshore natural gas well sites in the U

. S

. and

compare the data to the EPA ’s Inventory of U.S. Greenhouse Gas Emissions and Sinks (GHG Inventory ) . The sources and operations that were tested included well completion flowbacks,

well liquids unloading, pneumatic pumps and controllers and equipment leaks. The full study

a nalysis included 190 onshore natural gas sites
, which included 150 production sites, 26 well completion events , 9 well unloading and 4 well recompletions or workovers.

S ix of the completion events in the UT Study were at co

- producing wells (at least some oil was produced)

. The study reported the total oil produced, the total associated gas produced, the potential and actual methane emission, the completion duration, t he type of emission control used, and the percent reduction fro m the control that was observed (Note: f or two of the completion events, data was not gathered for the initial flow to the open tank )

. The data for these

wells are summarized in Table 3

- 6

.18 

### Table 3

- 6

. Summary of Completion Emission s from Co

- Producing Wells

Site ID Oil Produced (bbl) Gas

Produced (Mcf) GOR

(scf/bbl) Potential

Methane Emissions a (Mcf) Actual

Methane Emissions b (Mcf) %

Reductio

n Data Analyzed Duration

(hrs) REC

or Flare

GC

- 1 1 ,594 6,449

. 9 4,046.36 5,005 106 97.9 Yes 75 Flare

GC

- 2 1,323 5,645 4,266.82 4,205 91 97.8 Yes 76 Flare

GC

- 3 2,395 26,363 11,007.52 21,500 264 98.8 Yes 28 REC

GC

- 4 1,682 24,353 14,478.60 13,000 180 98.6 Yes 28 REC

GC

- 6 448 13,755 30,703.13 12,150 247 98 No d 164 Flare

GC

- 7 1,543 5,413 3,508.10 4,320 90 97.9 No d 108 Flare

a

– Measured emissions before flare or REC. b

- Measured emissions after flare or REC.

c

- Calculated from measured before and after control. d

- Data not used in developing average emis sions factor in the UT Study because, in these flowbacks, the study team was unable to collect complet ion emissions data for the initial flow to the open tank.



### Using the threshold of a GOR of 12,500 scf/barrel to distinguish oil wells from g as wells,

well s GC

- 1, GC

- 2, GC

- 3 , and GC

- 7 would be considered oil wells. The average uncontrolled

methane emissions from those wells were 213 tons ( 10,237 Mcf ) and the average controlled (actual) emissions were 3.2 tons ( 154 Mcf )

. 6 

### The average duration of the completio n for these wells was 72 hours (3 days). It is also worth noting that well GC

- 3 was controlled using a REC and 98.8% of the potential methane emissions were mitigated, demonstrating that RECs can be used effectively to control emissions from hydraulically fractured oil wells.

3.6 Methane Leaks from North American Natural Gas Systems ( Brandt et. al, 2014 a
and 2014b )

Novim, a non

- profit group at the University of California, sponsored a meta

- analysis of the existing studies on emissions from the production a nd distribution of natural gas. As part of this analysis
, Novim estimated emissions from hydraulically fractured oil well completions based

on data from HPDI®. Novim included wells that were drilled in 2010 or 2011 in the Eagle Ford,

6 These averages do not include well GC

- 7, because, as noted above, data from this well was not used in the UT Study due to the inability to collect all the emissions data.19



### Bakken, and Permian fo rmations ( Brandt et. al., 2014a) . Different filters were applied in each formation in order to identify the hydraulically fractured oil wells:

 Eagle Ford

o Well Production Type: Oil

o Drill Type: Horizontal

 Bakken

o Well Production Type: Oil and Oil & Gas

o Drill Type: Horizontal

 Permian

o Well Production Type: Oil

o Drill Type: All

Using this method of qualifying the well population, Novim concluded 2,969 hydraulically fractured oil wells were completed in 2011 in the three formations ( Brandt et. al.
, 2014a) . In ord er to estimate completion emissions
, Novim used the O’Sullivan method 7 

### in which peak gas production (normally the production during the first month) is converted to a daily rate of production. The O’Sullivan method assumes that during flowback emissions in crease linearly over the first nine days until th e peak rate is reached. Table 3

- 7 summarizes the estimated uncontrolled methane emissions per completion calculated by the Novim study

.

Table 3

- 7 . Summary of Uncontrolled Completion Emissions from Co

- Produc ing Wells

Formation Uncontrolled Methane Emissions (tonnes/event) a Uncontrolled

Methane Emissions (ton/event) b
Eagle Ford 90.9 93

Bakken 31.1 31.9

Permian 31.2 31.9

a

– 1 Mg = 1 metric ton ne of methane b

– Converted to U

. S

. short tons. 1 tonne = 1.023 11 tons (short/U

. S

. ) of methane

7 O’Sullivan, Francis and Sergey Paltsev, “Shale gas production: potential versus actual greenhouse gas emissions”, Environmental Research Letters, United Kingdom. November 26, 2012.20



### The Novim Study assumes methane emissions from these formations are representative of total national methane emissions from hydraulically fractured oil well completions and estimates those emissions to be 0.12 Tg (120,000 to nnes or 122,773 tons ) per year for 2011.

It should be noted that the methodology in this study, like the ERG/ECR Analysis and the

EDF /Stratus Analysis, uses gas production from HPDI® to estimate completion emissions. However, Novim uses the O’Sullivan met hod in which the emissions increase linearly through the flowback period until a peak is reached , while the ERG/ECR Analysis and the EDF/Stratus Analysis assume emissions are constant through the flowback period

.



## 4.0 EMISSIONS DATA AND EMISSIONS ESTIMATES

– ASSOCIATED

GAS FROM HYDRAULICALLY FRACTURED OIL WELLS

Given the potential for emissions of associated gas from oil production
, available

information sources have been reviewed as to their potential use for characterizing the VOC and

methane emission fr om associated gas production at oil well sites. As was stated previously, the term “associated gas emissions” in this paper refers to emissions from gas that is vented during the production phase that could otherwise be captured and sold if the necessary p ipeline infrastructure was available to take the gas to market.

One methodology for estimating emissions would be to use the GOR of the well, which is a common piece of well data in the industry. An emission factor based on average GOR could be develope d , and the n the emission factor could be used to estimate uncontrolled associated gas emissions by applying it to known oil production (assuming all gas produced at an oil well is included in uncontrolled associated gas emissions) . However, research indica tes that associated gas production from oil wells declines over the life of the well, similar to oil production , but the decline is typically at a different rate than the oil production (EERC, 2013)

. This phenomen on
introduces another variable into the ana lysis

.

A second approach would be to use gas production reported for the well for economic and regulatory reasons

. Conceivably
, gas production could be used to estimate uncontrolled21



### associated gas emissions. However, the EPA is not aware of a methodolog y that would allow the Agency to calculate the percentage of produced gas that could be captured if pipeline

infrastructure were available

. S ome gas is emitted from equipment as part of normal operations, such as bleeding from pneumatic controllers. These emissions would not qualify as associated gas emissions as they have been defined in this paper.

The GHGRP does require reporting of “associated gas venting and flaring emissions

. ” Additionally, the C eres report contains data potentially useful for basic evaluation of VOC and

methane associated gas emissions , but does not provide national estimates or per well estimates

of emissions (C eres , 2013)

. Both these sources are discussed in detail in the sections below.

The GHG Inventory does not include a categ ory that specifically covers all associated gas emissions. Instead, these emissions are estimated in several categories in Petroleum Systems, and in Natural Gas Systems (emissions downstream of the gas

- oil separator, and flaring).

4.1 Greenhouse Gas Repo rting Program (U.S. EPA, 2013)

In October 2013, the EPA released 2012 greenhouse gas (GHG) data for Petroleum and Natural Gas Systems 8 

### collected under the G HGRP . The GHGRP, which was required by Congress in the FY2008 Consolidated Appropriations Act, requi res facilities to report data from large emission sources across a range of industry sectors, as well as suppliers of certain GHG s and products that would emit GHGs if released or combusted.

When reviewing this data and comparing it to other datasets or published literature, it is important to understand the GHGRP reporting requirements and the impacts of these requirements on the reported data. The GHGRP covers a subset of national emissions from

Petr oleum and Natural Gas Systems; a facility 9 

### in the Petr oleum and Natural Gas Systems source

8 The implementing regulations of the Petroleum and Natural Gas Systems source category of the GHGRP are located at 40 CFR Part 98 Subpart W.
9 In general, a “facility” for purposes of the GHGRP means all co

- located emission sources that are commonly owned or operated. However, the GHGRP has d eveloped a specialized facility definition for onshore production. For onshore production, the “facility” includes all emissions associated with wells owned or operated by a single company in a specific hydrocarbon producing basin (as defined by the geolog ic provinces published by the American Association of Petroleum Geologists).22



### category is required to submit annual reports if total emissions are 25,000 metric tons carbon dioxide equivalent (CO 2 

### e) or more. Facilities use uniform methods prescribed by the EPA to
calculate GHG emissions, such as direct measurement, engineering calculations, or emission

factors derived from direct measuremen t. In some cases, facilities have a choice of calculation

methods for an emission source

. Under the GHGRP, f

acilities report associated gas vent ed and flared em issions

. Vented

emissions are calculated based on GOR and the volume of oil produced and flared emissions using a continuous flow measurement device or engineering calculation. For 2012, 171 facilities reported associated gas vented and flared emissions to the GHGRP

. Total reported methane

emissions were 89,535 MT.

4

. 2 FLARING UP: North Dakota Natural Gas Flaring More Than Doubles in Two Years (Flaring Up) (CERES, 2013)

The Flaring Up report discusses the increase in North Dakota’s oil and gas production

fr om the Bakken formation between 2007 and mid

- 2013
, the increased flaring of associated gas
, and the potential value of NGL lost as a result of flaring

. The report presents some associated gas production and flaring data that the authors derive from the gas production and flaring data reported by the North Dakota Industrial Commission (NDIC) , Department of Mineral Resources

. The Commission defines associated gas to be all natural gas and all other fluid hydrocarbons not

defined as oil. Oil is defined by the Commission to be all crude petroleum oil and other hydrocarbons
, regardless of gravity which are produced at the wellhead in liquid form and the liquid hydrocarbons known as distillate or condensate recovered or extracted from gas, other than gas produced in association with oil and commonly known as casinghead gas 10



### .

This Flaring Up report indicates that of the wells that are flaring the asso ciated gas, approximately 55 % are wells are not connected to a gas gathering system , while 45 % are wells

that are a lready connected . In addition, t he report states that in May of 2013, 266,000 Mcf per day was flared
, which represents nearly 30 % of the gas produced (CERES, 2013). Percent flaring is currently reported by the NDIC while the connection data is tracked by t he North Dakota

10 North Dakota Century Code, Section I, Chapter 38

- 08 Control of Gas & Oil Resources, Section 38

- 08

- 02.23



### Pipeline Authority. The report concludes that t he reason for the flaring of the associated gas is

lac k of pipeline infrastructure, lack of capacity and lack of compression infrastructure

.

The data and information in this report is useful for discussion on the relative percentages of gas emission s being flared. The data
, however
, are specific to the Bakken , a formation that

po sse sses unique characteristics both with regard to re s ervoir and formation characteristics , gas composition and the lack of infrastructure due to rapid development of the industry in the area.



## 5.0 AVAILABLE EMISSION MITIGATION TECHNIQUES

Two mitigation techniques were considered that have been proven in practice and in

studies to reduce emissions from well completions and recompletions: REC and completion combustion. One of these techniques, REC
, is an approach that not only reduces emissions but delivers natural gas product to the sales meter that would otherwise be vented. The second technique, completion combustion, destroys the organic compounds. Both of these techniques are discussed in the following sections, along with estimates of the efficacy at reducing

emissions and costs for their application for a representative well

. Combustion control for control

of assoc iated gas emissions (e.g.
, flaring) has been demonstrated as effective in the industry. However, flaring results in the destruction of a valuable resource and
, as such, alternate uses for uncaptured/sold associated gas ha ve been the subject of several stud ies with respect to new emerging technologies.

5 .1 Reduced Emission Completion s (REC)

5 .1 .1 Description

Reduced emissions completion s are defined for the purposes of this paper as:

A well completion following fracturing or refracturing where gas flowback that is otherwise vented is captured, cleaned, and routed to the flow line or collection system, re

injected into the well or another well, used as an onsite fuel source, or used for other24



### useful purpose that a purchased fuel or raw material would serve, with no direct release to the atmosphere

.

Reduced emission completions, also referred to as “green” completions, use specially designed equipment at the well site to capture and treat gas so it can be directed to the sales line. This process prevents some natural gas from venting and results in additional economic benefit from the sale of captured gas and, if present, gas condensate

. I t is the EPA’s understanding that

the a dditional equipm ent required to conduct a REC may include additional tankage, specia l gas

liquid

- sand separator traps and a gas dehydrator. In many cases, portable equipment used for RECs operate s in tandem with the permanent equipment that will remain after well drilling is completed (EC/R, 2010 b )

. In other instances, permanent equipment is designed (e.g.
, oversized) to specifically accommodate initial flowback. Some limitations exist for performing RECs

because technical barriers vary from well to well. Three main limitations include the following:

 Proximity of pipelines . For certain we lls, no nearby sales line may exist. The lack of a nearby sales line incurs higher capital outlay risk for exploration and production companies and/or pipeline companies constructing lines in exploratory fields.

 Pressure of produced gas

. Based on experie nce using RECs at gas wells, the EPA

understands that d uring each stage of the completion process, the pressure of flowback fluids may not be sufficient to overcome the sales line backpressure. In this case, combustion of flowback gas is one option, eithe r for the duration of the flowback or until a point during flowback when the pressure increases to flow to the sales line.

 Inert gas concentration

. Based on experience using RECs at gas wells, i f the concentration of inert gas, such as nitrogen or carbon dioxide, in the flowback gas exceeds sales line concentration limits, venting or combustion of the flowback may be necessary for the duration of flowback or until the gas energy content increases to allow flow to the sales line. Further, since the energy content of the flowback gas may not be high enough to sustain a flame due to the presence of the inert gases, combustion of the flowback stream would require a continuous ignition source with its own separate fuel supply.25



### 5

. 1.2 Effectiveness

Based on dat a available on RECs use at gas wells, t he emission reductions from RECs

can vary according to reservoir characteristics and other parameters including length of completion, number of fractured zones, pressure, gas composition, and fracturing technology/tec hnique. Based on the results reported by four different Natural Gas STAR Partners who performed RECs primarily at natural gas wells , a representative control efficiency of 90 %

for RECs was estimated . The companies provided both recovered and total produced gas, allowing for the calculation of the percentage of the total gas which was recovered. This estimate was based on data for more than 12,000 well completions (ICF, 2011)

. Any amount of gas that cannot be recovered can be directed to a completion combust ion device in order to achieve a

minimum 95 % reduction in emissions. Additionally, both wells that co

- produced oil and gas and

were controlled with a REC in the UT Austin study achieved greater than 98 % reduction in

methane emissions.

5 .1.3 Cost

The discus sion of cost in this section is based on the EPA ’s experience with RECs at gas

wells. It is the EPA ’s understanding that the same equipment is used for RECs at gas wells and

co

- producing oil wells. All completions incur some costs to a company. Performing a REC will add to these costs. Equipment costs associated with RECs vary from well to well. High production rates may require larger equipment to perform the REC and will increase costs. If permanent equipment, such as a glycol dehydrator, is already insta lled or is planned to be in place at the well site as normal operations, costs may be reduced as this equipment can be used or resized rather than installing a portable dehydrator for temporary use during the completion. Some operators normally install equ ipment used in RECs, such as sand traps and three

- phase separators, further reducing incremental REC costs.

The average cost of RECs was obtained from data shown in the Natural Gas STAR Lessons Learned document titled “Reduced Emissions Completions for H ydraulically Fractured
Natural Gas Wells” (U

. S

. EPA, 2011 a )

. The impacts calculations use the cost per day for gas26



### capture and the duration of gas capture along with a setup/takedown/transport cost and a flare cost to represent the total cost. The cost is then annualized across the time horizon under study.

Costs of performing a REC are projected to be between $700 and $6,500 per day (U

. S

. EPA, 2011 a )

. This cost range is the incremental cost of performing a REC over a completion

without a REC , where typic ally the gas is vented or combusted because there is an absence of REC equipment. T hese cost estimates are based on the state of the industry in 2006 (adjusted to
2008 U

. S

. dollars). 11 

### Cost data used in this analysis are qualified below:

 $700 per day (equ ivalent to $806 per day in 2008 dollars) represents completion and recompletion costs where key pieces of equipment, such as a dehydrator or three

- phase separator, are already found onsite and are of suitable design and capacity for use during

flowback.

 $ 6,500 per day (equivalent to $7,486 in 2008 dollars) represents situations where key pieces of equipment, such as a dehydrator or three

- phase separator, are temporarily brought onsite and then relocated after the completion.

T he average of the above data results in an average incremental cost for a REC of $4,146 per day (2008 dollars). 12 

### The total cost of the REC depends on the length of the flowback period, and thus the length of the completion process. For example, if the completion takes 7 days then

the total cost would be $29,022

, and if the completion takes 3 days then the total cost would be $12,438 versus an uncontrolled completion. These costs would be mitigated by the value of the captured gas. The extent of this cost mitigation would depend on the price of the gas and the quantity that was captured during the REC.

11 The Chemical Engineering Cost Index was used to convert dollar years. F or REC, the 2008 value equals 575.4 and the 2006 value equals 499.6.
12 The average incremental cost for a REC was calculated by averaging $806 per day and $7,486 per day (2008 dollars). While the average estimated cost per day is presented here
, it is like ly that the cost that is paid by a well operator will be the low incremental cost if key pieces of equipment are already present onsite or the high incremental cost if this equipment is not present onsite, and not the average of these two estimates.27



### 5 .1.4 Prevalence of Use at Oil Wells

The UT Austin study found that some co

- producing oil wells are conducting RECs. It is

the EPA’s understanding that in some cases RECs are currently u sed on co

- producing oil well s if pipeline infrastructure is available.

5

. 2 Completion Combustion Devices

5. 2.1 Description

Completion combustion is a high

- temperature oxidation process used to burn combustible components, mostly hydrocarbons, found in gas streams (U

. S

. EPA, 1991)

. Completion

combustion devices are used to control VOC in many industrial settings, since the completion

combustion device s can normally handle fluctuations in concentration, flow rate, heating value, and inert species content (U

. S

. EPA, Flares)

. These devices can be as simple as a pipe with a basic ignition mechanism and discharge over a pit near the wellhead. However, the flow directed to a completion combustion device may or may not be combustible depending on the inert gas

comp osition of flowback gas, which would require a continuous ignition source. Completion

combustion devices provide a means of minimizing vented gas during a well completion and are generally preferable to venting , due to reduced air emissions

.

5

. 2.2 Effecti veness

C ompletion combustion devices can be expected to achieve 95 % emission reduction efficiency , on average, over the duration of the completion or recompletion. If the energy content of natural gas is low, then the combustion mechanism can be extinguish ed by the flowback gas.
Therefore, it may be more reliable to install an igniter fueled by a consistent and continuous ignition source. This scenario would be especially true for energized fractures where the initial

flowback concentration will be extremel y high in inert gases. If a completion combustion device

has a continuous ignition source with an independent external fuel supply
, then it is assumed to achieve an average of 95 % control over the entire flowback period (U.S. EPA, 2012b )

.28



### 5

. 2.3 Cost

A n analysis of costs provided by industry for enclosed combustors was conducted by the

EPA for the FBIR FIP. In addition, the State of Colorado recen tly completed an analysis of industry provided combustor cost data and updated their cost estimates for enclosed combustors ( CDPE, 2013 )

. Table 5

- 1 summarizes the data provided from each of the sources with the average cost for an enclosed combustor across these sources being $18,09 2

. It is assumed that the cost of a continuous ignition source is included in the combustion completion device cost

estimations. Also noted in the table is the most recent combustor cost used for reconsideration of control option s for storage vessels under s ubpart OOOO

. As with REC s , because completion combustion devices are purchased for these one

- time events, annual costs were assumed to be equal to the capital costs. However, multiple completions can be controlled with the sam e completion combustion device, not only for the lifetime of the combustion device but within the same yearly time period. C osts were estimated as the total cost of the completion combustion device itself, which corresponds to the assumption that only one device will control one completion per year. This approach may overestimate the

true cost of combustion devices per well completion or recompletion.

5.2. 4 Prevalence of Use at Oil Wells

The UT Austin study found that some co

- producing oil wells are using completion

combustion devices to reduce emissions. It is the EPA’s understanding that the most common approach to reducing emissions from hydraulically fractured oil well completions is the use of a completion combustion device.29 

### Table 5

- 1

. Analysis of I ndustry Provided Enclosed Combustor Cost

Cost Parameter Industry Provided Data EPA Estimate in Subpart OOOO

FBIR CDPHE CDHPE

EOG XTO Enerplus QEP Average of quotes Original Data Used Adjusted Data Used a

Annualized Capital Cost $5,268 $6,727 $6,11 6 $6,763 $3,569 $6,281 $3,546 $4,746

Other Annual Costs

Pilot Fuel NR NR NR NR $636 $2,078 $2,144
Operating Labor (includes management) NR NR NR NR $10,670 $10,670 $11,012

Maintenance NR NR NR NR $2,206 $2,190 $2,260

Data Management NR NR NR NR $1 ,000 $1,095 $1,130

Total Other Annual Costs (combustor) c $1,500 $23,250 $6,289 $8,500 $14,512 $10,810 $16,033 $16,546

Other Annual Costs (continuous pilot) c $1,000 NR NR NR included in combustor
costs b $1,000 included in combustor costs b included in

com bustor costs c

Total Annual Costs $7,768 $29,977 $12,405 $15,263 $18,081 $18,092 $19,580 $21,292

NR = Not reported , FBIR = Fort Berthold Indian Reservation, CDPHE = Colorado Department of Public Health and Environment , EOG = EOG Resources , XTO = XTO Energ y Inc. , QEP = QEP Energy Co Cost data in 2012 dollars

a

- Cost d a ta for 40 CFR part 60, s ubpart OOOO updated to reflect more current cost year and equipment life (industry comments indicated a 10

- year equipment life as opposed to 15 years) b

- Data used f

or s ubpart OOOO included a cost for an auto ignition system , surveillance system, VRU system, and freight and installation

c

- Quotes received for FBIR FIP did not specify what was included in other annual costs.30



### 5.3 Emerging Control Technologies for Con trol of Associated Gas

Several types of alternative use technologies are being investigated both by industry and regulators for use of associated gas

.

The most prominent alternative technologies being investigated to address associated gas

are liquefac tion of natural gas, NGL recovery, gas reinjection, and electricity generation.

According to the Schlumberger Oilfield G lossary
, “liquefied natural gas refers to natural gas, mainly methane and ethane, which has been liquefied at cryogenic temperatures. This process occurs at an extremely low temperature and a pressure near the atmospheric pressure. When a gas pipeline is not available to transport gas to a marketplace, such as in a jungle or certain remote regions offshore, the gas may be chilled and converted to liquefied natural gas (a liquid) to transport and sell it. The term is commonly abbreviated as LNG .” R esearch is being conducted on the economic and technical feasibility of liquefaction of natural gas as a means to realize the full potential of the U

. S

. natural gas resources , particularly with respect to the potential of U

. S

. exports of LNG. Howev er, available information indicates that t his technology is typically implemented on a macro scale, requiring installation of large facilities and transportation infrastructure

. Because the EPA is unaware of existing studies or further information on lique faction of gas at the wellhead
, liquefaction of natural gas is not discussed

further in this paper

.

C ost information is summarized to the extent that this information is readily available. In many cases, available literature does not provide cost informa tion as the economic s of the technology are still being researched.

5.3.1 Natural Gas Liquids (NGL ) Recovery

Natural gas liquids are defined as “c omponents of natural gas that are liquid at surface in field facilities or in gas

- processing plants. Natural gas liquids can be classified according to their vapor pressures as low (condensate), intermediate (natural gasoline) and high (liquefied petroleum gas) vapor pressure . Natural gas liquids include propane, butane, pentane, hexane and31



### heptane, but not methane and ethane, since these hydrocarbons need refrigeration to be liquefied. The term is commonly abbreviated as NGL

. ” 13



### Asso ci ated gas from the Bakken formation has been termed “rich” gas

, which is defi ned

as natural ly containing heavier hydrocarbons than a “ lean ” gas. Its liquid content adds important economic value to developments containing this type of fluid. Th erefore, th e value of the NGLs in the associated gas from the Bakken formation has been th e subject of several studies, particularly with the concerns raised based by the rapid development of Bakken and increased flaring of associated gas. As would be expected, most of the recent studies related to NGL recovery are based on the Bakken formation

.

One of these studies is the “End

- Use Technology Study

– An Assessment of Alternative
Uses for Associated Gas” conducted by the Energy & Envi ronm ental Research Center (EERC) of the University of North Dakota (EERC, 2013 )

. The study was conducted based o n associated gas production in December 2011 and was published in 2012. This study provides an evaluation

of alternative technolog ies and their associated costs and benefits. In particular, the study looks

at NGL recovery, as a standalone operation for bot h recovery of salable NGLs and as a pretreatment of the associated gas for use in other local operations such as power genera tion.

To understand NGL recovery, the typical natural gas processing that occurs at or near the

wellhead will be reviewed . Liquid s and condensates (water and oil) are separated from the “wet” gas. The condensates are transported via truck or pipeline for further processing at a refinery or gas processing plant. The minimally processed wellhead natural gas is then transported to a ga s

processing plant via pipeline. There, the gas is processed to remove more water, separate out

NGL , and remove sulfur and carbon dioxide in preparation for release to the sales distribution
system. Figure 5

- 1 summari z es generalized natural gas processing.

13 From Schlumberger Oilfield Glossary available at http://www.glossary.oilfield.slb.com/en/Terms.aspx?LookIn=term%20name&filter=natural+gas++liquids32 

### Figure 5

- 1

. Generalized N atural G as P rocessing S chematic

Source: U.S. EIA, 2006.



### Because of the relatively high value of NGL products produced, recovery technolog ies have been developed both for large and small scale gas

- processing applications . The re are generally three approaches used in these technologies:

• Control of temperature and pressure to achieve condensation of NGLs

• Separation of heavier NGLs from lighter gas with pressurized membrane separation
systems

• Physical/chemical adsorption/abso rption

The typical NGL recovery technologies used are turboexpander with demethanizer,

Joule

- Thomson ( JT ) low pressure separation membranes, absorption (Refrigerated Lean Oil Separation, RLOS), adsorption using active carbon or molecular sieve, and Twist er Supersonic Gas Low Temperature Separation Dew Pointing Process. For the purposes of this paper, the33



### specifics of these technologies are not discussed; rather, the focus will be on the overall outcome and potential costs for small scale implementation at the well head for addressing associated gas.

The EERC study included a case study for a small scale NGL Recovery process at a well head. The case study evaluate d the potential for deploying small scale NGL recovery systems as an interim practice to fla ring associated gas whil e gathering lines and infrastructure were being installed or upgraded. These systems would allow the most valuable hydrocarbon portion of the gas to be capture d and marketed. The leaner gas resulting could be used onsite for power

g eneration or transported as a compressed gas. Alternatively, the leaner gas could continue to be

flared. Figure 5

- 2 depicts the NGL Removal system flow diagram.

Figure 5

- 2

. Natural Gas Liquids (NGL) Removal System Flow Diagram

Source: Figure 22 , EERC, 2013



### According to the EERC study, 10 to 12 gallons of NGL/Mcf of associated gas is present in many producing Bakken wells. At an estimated NGL removal rate of 4 gallons/Mcf (from 1000 Mcf/day of rich gas), the daily production of NGLs would be approximately 4
, 000 gallons of NGLs per day ( EERC, 2013 )

. The study also states that at least at the current natural gas price,

the NGLs make up a majority of the economic value of the rich gas . An evaluation of a simplified model on smal l

- scale NGL recovery was developed based on a JT

- based technology. The NGL removal system evaluation assumes the parameters shown in Table 5

- 2

.34 

### Table 5

- 2

. Assumptions for NGL Recovery Case (Table 9, EERC, 2013 )

Parameter Assumed Value

Rich Gas Flo w Rate from the Wellhead, average 300 Mcf/day
Rich Gas Flow Rate Processed, economic cutoff 600 Mcf/day
Rich Gas Flow Rate, design flow 1000 Mcf/day

Rich Gas Heat Content 1400 Btu/ft 3



### Rich Gas Price (cost) at the Wellhead $0.00/Mcf

Volume of NGLs Existing in Rich Gas 10

– 12 gallons/Mcf
NGL Price, value $1.00/gallon
Lean Gas Flow Rate from NGL Removal System 85% of rich gas flow rate

Lean Gas Heat Content 1210

– 1250 Btu/ft 3



### Lean Gas Price, value $2.00/Mcf

The EERC study estimated c apital and annual costs f or the NGL removal system

. Operating and m aintenance (O&M) costs were assumed to be 10% of the total capital cost.
Revenue calculations were based on NGL sales only at $1/gallon and a recovery rate of 4 gal lons / M cf. In this scena rio, it has been assumed that residue gas is flared ( EERC, 2013 ). Table

5

- 3
, derived from Table 10 of the study
, summaries the cost for the small sale NGL recovery
system

.

Table 5

- 3

. Summary of NGL Removal System Costs (Table 10, EERC)

Description Capi tal Cost Annual O&M Cost
NGL Removal System, 300 Mcf d rich gas $2,500,000 $250,000

NGL Removal System, 600 Mcfd rich gas $2,500,000 $250,000

NGL Removal System, 1000 Mcfd rich gas $2,500,000 $250,000

Mcfd = One thousand standard cubic feet per da y


### .35



### The EERC study concluded that the technical aspects of NGL recovery are fairly straight

forward ; however, the business aspects are much more complicated, particularly with respect to NGL product supply chain and contractual considerations . Further, the study concluded that NGL recovery wo uld be most economical at wells flaring l arger quantities of gas immediately after production begins

. Other attributes that would be important for the economic feasibi li ty of the NGL recovery system would be that the sy stems are mobile and easily mobilized , and that infrastructure with respect to truing of NGL production is available.

5.3. 2 Natural Gas Reinjection

Schlumberger’s Oilfield Glossary defines gas injection as “ a reservoir maintenance or secondary recovery method that uses injected gas to supplement the pressure in an oil reservoir

or field . In most cases, a field will incorporate a planned distribution of gas

- injection wells to

maintain reservoir pressure and effect an efficient sweep of recoverable liquids.” 14



### The industry has employed production methods to increase production, which are termed enhanced oil recovery (EOR) or imp roved oil recovery (IOR) ( Rigzone , 201 4 )

. These methods are generally considered to be tertiary methods employed after waterflooding or pressure

maintenance. The practice involves injecting gas into the gas cap of the formation and boosting the depleted pr essure in the formation with systematically placed injection wells throughout the field. The pressure maintenance methods maybe employed at the start of production or introduced after the production has started to lessen. The reinjection of natural gas is the use of associated gas at the same oilfield to accomplish the goals of gas injection as defined above. The increase in the pressure within the reservoir helps to induce the flow of crude oil. After the crude has been pumped out, the natural gas is once again recovered.

Natural g as injection is also referred to as cycling. Cycling is used to prevent condensate from separating from the dry gas in the reservoir due to a drop in reservoir pressure

. The condensate liquids block the pores within the reservoi r, making extraction practically impossible.

The NGL are stripped from the gas on the surface after it has been produced, and the dry gas is

14 Schlumberger Oilfield Glossary, available at http://www.glossary.oilfield.slb.com/en/Terms.aspx?LookIn=term%20n ame&filter=gas+injection36



### then re

- injected into the reservoirs through injection wells. Again, this helps to maintain pressure

in the reservo ir while also preventing the separation within the hydrocarbon ( Rigzone , 201 4 )

. Figure 5

- 3 illustrates the relationship between the gas injection well and the production well.

Figure 5

- 3. Gas Injection and Production Well

Source: Rigzone , 201 4



### In the s cenarios that were found in available literature , the dry gas is also used as fuel onsite for the generators that power the reinjection pumps. Therefore, the costs associated with the process are mainly initial capital costs. No published information was o btained on the capital and annual costs for these operations.

Figure 5

- 4 presents a fully implemented gas injection project scheme. In this scheme, associated gas from an oil well (or natural gas from a gas well) is processed through a gas cycling facili ty (GCF) where recoverable NGLs are separated from methane and the resulting methane is either used for onsite power generation or re

- injected in to the formation.37 

### Figure 5

- 4. Gas Cycling Facility Project Flow

The literature that was reviewed evaluated gas reinjection projects only from the perspective of an enhanced oil recovery opportunity and did not specifically discuss the quantity or percentage of associated gas emissions that were eliminated through the process. The EPA is

not aware of literature that discusses the efficacy of mitigating associated gas emissions using the natural gas reinjection process. The efficacy would be highly dependent on many factors, which include the composition value of the gas and the availability of transmission infra structure. Further, because the use of this process to reduce associated gas emissions in conjunction with oil recovery is an emerging technology, the prevalence of use in the industry and estimated cost to implement the process is unknown to the EPA.38



### 5.5. 3 Electricity Generation for Use Onsite

As discussed above, associated gas can be used for generation of electrical power to be

used onsite

. The EERC study stated that power generation technologies would need to be designed to match the variable wellhead gas flow rates and gas quality, and would need to be constructed for mobility. The EERC study discussed previously also looked at options for use of associated gas for power generation. The EERC s tudy included an evaluation of several technologies fired by natural gas both for grid support (i.e., power generation for direct delivery onto the electric grid) and local power (i.e., po w er generation for local use with excess generation
, if any
, sent to the electrical grid )

. This study provides one of the most c omprehensive and recent evaluations of the economics of use of associated gas for electric generation. Therefore, the case study results of this study are used to discuss the cost of this technology for this paper.

Although grid support is potentially a v iable use for this gas, it is not considered to be an emissions reduction technology for the purposes of this paper. Grid support requires an infrastructure similar in scope as that needed to bring gas to market. The focus of this section of the paper is o n the venting or flaring of associated gas due to the lack of infrastructure to bring it to market. It is unlikely that a well site that is lacking pipeline infrastructure would have access to the necessary infrastructure to provide grid support. Therefore , the focus here is on the use of the gas at the local level, either directly at the wellpad or in an immediate oilfield region to support local activities. The benefits of using associated gas to provide electricity for these activities are both reducing the quantity of gas vented and reducing the quantity of other types of fuel used (e.g., diesel).

The EE R C study considered a local power project to be wellhead gas (with limited cleanup) being piped to an electrical generator that produces electricity whi ch is first used to power local consumption (e.g., well pad, group of wells, or an oilfield) with any excess electricity put on the electrical grid for distribution by the local utility to its customers. These projects can range widely in scale, depending on the goal of the project (i.e., satisfy only local load, satisfy local load with minimal excess generation, or satisfy local load with significant39



### excess generation). The study evaluated t wo power generation scenarios : r eciprocating engine

and a microtur

bine.

The first step in using associated gas for electric generation is removal of NGLs from the rich gas . Removal of the NGLs significantly increases the performance of the genset and reduces the loss of resource (when flaring is necessary). According t o the EERC study
, removal of NGLs such as butane and some propane could be accomplished using a low temperature separation process. The study found that small, modular configurations of these types of systems are not widely available. The estimated capital cost for the NGL removal and storage system is $2,500,000. This capital cost includes the necessary compression to take the rich gas from the heater/treater at 35 psi up to 200

- 1000 psi delivered to the NGL removal system as well as the

cost for four 40 0

- bbl NGL storage tanks (EERC , 2013 ). The study authors considered NGL recovery a valuable first step ; however, they also stated that it was not necessary in all

circumstances

.

The study made certain assumptions about the flow of associated gas from the w ellhead

and fuel consumption of the respective electrical generator for the case study. Table 5

- 4 summarizes the assumed wellhead gas flow for the case study. Figure 5

- 5 shows a block flow diagram of an example NGL removal system.

Table 5

- 4 . Summary of W ellhead Gas Flow and Product Volume Assumptions

Scenario Rich Gas

Flow, Mcf/day NGLs Produced, gallons/day Lean Gas

Produced, Mcf/day Reciprocating Engine 

### 600 2,400 510

Microturbine 600 2,400 510
Source Table 33, EERC 201340 

### Figure 5

- 5. NGL R emoval S ys tem B lock F low D iagram

Source Figure 32, EERC 2013



### F or the case study, the authors targete d a power production scenario of 1 MW for the reciprocating engine and 200 kW for the microturbine. Both scenarios used the same NGL

rem oval system prior to introduction of the rich g as to the generator. Figure 5

- 6 depicts the process flow diagram for the local power gen e ration scenario.

Figure 5

- 6. Process F low D iagram, L ocal P ower G eneration S cenario

Source: Figure 33, EERC, 2013



### F or the reciprocating engine scenario, vendor provided costs for a 250

- kW natural gas fired reciprocating engine genset was $200,000 . The study estimated the annual O&M cost was assumed to be 10% of the capital cost. The costs for this scenario are summariz ed in Table 5

- 5

.41 

### Table 5

- 5

. Total Cost Summary

- Reciprocating Engine Scenario

Capital Cost Annual Cost NGL Removal and Storage System $2,500,000 $250,000
Electrical Generator System $200,000 $20,000

All Other Infrastruc t ure $500,000

Total Ca pital Cost $3,200,000 $270,000

Source Table 38 , EERC 2013



### For the microturbine s cenario
, the authors chose to analyze a four, 65 kW microturbine package rated to provide approximately 195 kW of power . This scenario also involved the removal of NGLs prior to delivery of gas to the microturbine and the use of generated electricity to satisfy local electrical demand, with the excess electricity delivered to the grid. The authors noted that the volume of gas generated from the wellhead(s) will determine the si ze of the system needed and that a range of generation scales should be considered for optimum performance. The process flow for this scenario is the same as shown above in Figure 5

- 6

.

T he NGL removal system is likely to be much larger in processing capa city than the electrical generation system. Generally, the NGL removal system will be most economical only at the higher

- gas

- producing wells . The microturbine package evaluated consumed less than 100 Mcf/day
, which meant that excess gas would either need t o be flared or the project must be designed to store the excess gas for sale to the pipeline. In the scenarios described here, the

authors assumed that the excess lean gas is sold.

For the microturbine system analyzed, the vendors offered a factory prote ction plan (FPP) that covers all scheduled and unscheduled maintenance of the system as well as parts, including an overhaul or turbine replacement at 40,000 hours of operation. The FPP “locks in” the annual O&M cost of the system and
, in both scenarios pr esented below, it is assumed that the FPP is purchased (EERC , 2013 )

. Table 5

- 6 summarizes the capital and annual O&M costs for the microturbine system, as well as the NGL recovery system discussed above.42 

### Table 5

- 6

. Total Cost Summary

- Microturbine Scen ario (Four 65

- kW )

Capital Cost Annual Cost NGL Removal and Storage System $2,500,000 $250,000
Electrical Generator System $ 383,200 $ 33,640

All Other Infrastruc t ure $500,000

Total Capital Cost $3, 382,200 $ 283,640

S ource: Table 41 , EERC, 2013

.


### Th e study authors also evaluated revenue potential for electricity sent to the grid as an offset to the costs summarized above. Their analysis indicated that b ased on cost (discussed above) and their revenue assumptions , both scenarios provided a simple payb ack of 3 years or

less. However, given the substantial upfront capital costs of these options, these options may not be preferable to building the necessary pipeline infrastructure to take the gas to market.

In addition to the electric generation potentia l for associated gas, the study also discussed

the use of wellhead gas as a fuel for drilling operations . The authors indicated that the EERC is working with Continental Resources, ECO

- AFS, Altronics, and Butler Caterpillar to conduct a detailed study and field demonstration of the GTI Bi

- Fuel System. Within that task, the EERC conducted a series of tests at the EERC using a simulated Bakken gas designed to test the operational limits of fuel quality and diesel fuel replacement while monitoring engine perfo rmance and emissions. The authors indicated that the Bi

- Fuel System is an aftermarket addition to the system allowing natural gas to the air intake
, and the engine performance is unaltered from the diesel operation. This system
, as the name implies
, could be used on either

fuel without requiring any alterations.

According to the study report
, t otal installed capital cost for the Bi

- Fuel System ranges from $200,000 to $300,000 ( EERC, 2013)

. Other costs that would be incurred would be those for piping wellhe ad gas to the engine building. The study did not include those costs because they can be highly variable depending on the distance to the nearest gas source and gas lease terms.43



### The study reports that ECO

- AFS ha d recently installed several Bi

- Fuel Syste ms on rigs in

the Williston Basin and that e arly data suggest that diesel fuel savings of approximately $1 to $1.5 million can be achieved annually. Under typical conditions, operators can expect to achieve diesel replacement of 40%

- 60% at optimal engine loads of 40%

- 50% (EERC
, 2013)

.

The EERC study noted that there are a number of other potential natural gas uses related to oil production and operations that could take advantage of rich gas on a well site. Those would

include:

 Heating of d r illing fl uids during winter months (replacing the diesel or propane fuel used currently)

 P rovid ing power for hydraulic fracturing operations decreasing reliance on diesel fuel ( i .e. , by using Bi

- fuel system s )

 Providing fuel for workover rigs (if the rig is equi pped with a separate generator)



## 6.0 SUMMARY

As discussed in the previous sections, the EPA used the body of knowledge presented in this paper to summarize its understanding of emissions characterization and potential emissions mitigation techniques for oil well completions and associated gas. From that body of knowledge
, the following statements summarize the EPA’s understanding of the state of the industry with
respect to these sources of emissions :

 Available estimates of uncontrolled emissions from hyd raulically fractured oil well completions are presented below:44 Study Average Uncontrolled VOC Emissions ( Tons/Completion ) Average Uncontrolled Methane Emissions ( Tons/Completion )
Fort Berthold Federal Implementation Plan 37 N/A
ERG/ECR Analysis of HP DI® Data (7 day flowback period) 20.2 24
ERG/ECR Analysis of HPDI® Data (3 day flowback period) 6.4 7.7

EDF/Stratus Analysis of HPDI® Data (Eagle Ford) N/A 27.2

EDF/Stratus Analysis of HPDI® Data (Wattenberg) N/A 10.5

EDF/Stratus Analysis of HPDI® Data (Bakken) N/A 19.8

Measurements of Methane Emissions at Natural Gas Production Sites in the United States N/A 213

Methane Leaks from North American Natural Gas Systems (Eagle Ford) N/A 90.9

Methane Leaks from North American Natural Gas Systems (Bakken) N/A 31.1

Methane Leaks from North American Natural Gas Systems (Permian) N/A 31.2



###  L imited information is available on uncontrolled emissions from hydraulically fractured

oil well recompletions, and controlled emission factors for hydraulically fractured oil well completions and recompletions.

 N ational level estimates of uncontrolled methane emissions from hydraulically fractured oil well completions range from 44,306 tons per year ( ERG/ ECR) to 247,000 tons per year (EDF/Stratus analysis).

 One study ( ERG / ECR) estimated nationwide uncontrolled VOC emissions from hydraulically fractured oil well completion to be 116,230 tons per year assuming a 7

- day flowback period and 36,825 tons per year assuming a 3

- day flowback period

.

 There is some data that shows (Al len et. al.) that RECs, in certain situations, can be an effective emissions control technique for oil well completions when gas is co

- produce d

.45



### However, there may be a combination of well pressure and gas content below which RECs are not technically feasi ble at co

- producing oil wells.

 Some oil well completions are controlled using RECs ; however, national data on the number of completions that are controlled using a REC are not available. It is the EPA’s understanding that most oil well completion emission s are controlled with combustion ; however, data on an average percentage are not available. Likewise, data are not
available on the percentage of oil wells nation

- wide that vent completion emissions to the atmosphere.

 Other gas conserving technologies are being investigated for use in completions and for control of associated gas emissions. These include gas reinjection, NGL recovery and use of the gas for power generation for local use. Some studies have evaluated the economics

of some of the se technologie s and determined
, in some cases
, they can result in net savings to the operator depending on the value of the recovered gas or liquids or the value of the power generated . However, some barriers exist with respect to technology availability and application of the technology to varying scales of oil well gas production.
In addition, cost s vary for implementing some of these technologies.



## 7.0 CHARGE QUESTIONS FOR REVIEWERS

1. Please comment on the national estimates and per well estimates of methane and VOC

emi ssions from hydraulically fractured oil well completions presented in this paper. Are there factors that influence emissions from hydraulically fractured oil well completions that were not discussed in this paper ?

2. Most available information on national and per well estimates of emissions is on

uncontrolled emissions. What information is available for emissions, or what methods can be used to estimate net emissions from uncontrolled emissions data, at a national and/or at a per

well level?

3. Are further sour ces of information available on VOC or methane emissions from hydraulically fractured oil well completions beyond those described in this paper?46



### 4. Please comment on the various approaches to estimating completion emissions from hydraulically fractured oil we lls in this paper.

 Is it appropriate to estimate average uncontrolled oil well completion emissions by using

the annual average daily gas production during the first year and multiplying that value by the duration of the average flowback period?

 Is it ap propriate to estimate average uncontrolled oil well completion emissions using
“Initial Gas Production ,” as reported in DI Desktop, and multiplying by the flowback period ?

 Is it appropriate to estimate average uncontrolled oil well completion emissions by increasing emissions linearly over the first nine days until the peak rate is reached (normally estimated using the produ ction during the first month converte d to a daily rate of production) ?

 Is the use of a 3

- day or 7

- day flowback period for hydraulically fractured oil wells appropriate?

5. Please discuss other methodologies or data sources that you believe would be appropriate for estimating hydraulically fractured oil well completion emissions

.

6. Please comment on the methodologies and data sources that you believe would be appropriate to estimate the rate of recompletions of hydraulically fractured oil wells. Can data on recompletions be used that does not differentiate between conventional oil wells and hydraulically fractured oil wells be reasonably used t o est imate this rate? For example, in the GHG Inventory, a workover rate of 6.5% is applied to all oil wells to estimate the number of workovers in a given year, and in the ERG/ ECR analysis above a rate of 0.5% is developed

based on both wells with and wit hout hydraulic fracturing. Would these rates apply to hydraulically fractured oil wells? For hydraulically fractured gas wells, the GHG Inventory uses a refracture rate of 1%. Would this rate be appropriate for hydraulically fractured oil

wells?

7. Please comment on the feasibility of the use of RECs or completion combustion devices during hydraulically fractured oil well completion operations. Please be specific to the types of wells where these technologies or processes are feasible . Some characteristics that should be considered in your comments are well pressure, gas content of flowback, gas to oil ratio47



### (GOR) of the well, and access to infrastructure. If there are additional factors, please discuss

those. For example, t he Colorado Oil and Gas Conservati on Commission requires RECs only

on “ oil and gas wells where reservoir pressure, formation productivity and wellbore conditions are likely to enable the well to be capable of naturally flowing hydrocarbon gas in flammable or greater concentrations at a sta bilized rate in excess of five hundred (500) MCFD to the surface against an induced surface backpressure of five hundred (500) psig or sales line pressure, whichever is greater. ” 15



### 8. Please comment on the costs for the use of RECs or completion combustion dev ices to control emissions from hydraulically fractured oil well completions.

9. Please comment on the emission reductions that RECs and com pletion combustion devices

achieve when used to control emissions from hydraulically fractured oil well completions.

10. Ple ase comment on the prevalence of the use of RECs or completion combustion devices during hydraulically fractured oil well completion and recompletion operations. Are you aware of any data sources that would enable estimating the prevalence of these technol ogies nationally?

11. Did the EPA correctly identify all the available technologies for reducing gas emissions from hydraulically fractured oil well completions or are there others?

12. Please comment on estimates of associated gas emissions in this paper, and on other available information that would enable estimation of associated gas emissions from hydraulically fractured oil wells at the national

- and the well

- level.

13. Please comment on availability of pipeline infrastructure in hydraulically fractured oil

forma tions. Do all tight oil plays (e.g., the Permian Basin and the Denver

- Julesberg Basin) have a similar lack of infrastructure that results in the flaring or venting of associated gas ?

14. Did the EPA correctly identify all the available technologies for reduc ing associated gas emissions from hydraulically fractured oil well s or are there others? Please comment on the

15 Colorado Department of Natural Resources: Oil and Gas Conservation Commission Rule 805.b(3)A. ( http://cogcc.state.co.us/ )48



### cost s of these technologies when used for controlling associated gas emissions from hydraulically fractured oil well s. Please comment on the emis sions reductions achieved when these technologies are used for controlling associated gas emissions from hydraulically

fractured oil well s.

15. Are there ongoing or planned studies that will substantially improve the current understanding of VOC and methane em issions from hydraulically fractured oil well completions and associated gas and available options for increased product recovery and

emission reductions?



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. Annual Energy Outlook 2013. Available at http://www.eia.gov/forecasts/aeo/pdf/0383%282013%29.pdf.
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. Air Pollution Control Technology Fact Sheet: FLARES . Clean Air Technology Center.

U.S. Environmental Prote ction Agency ( U.S. EPA)

. 1991. AP 42, Fifth Edition, Volume I, Chapter 13.5 Industrial Flares

. EPA/ Office of Air Quality Planning & Standards. 1991.
U.S. Environmental Protection Agency ( U.S. EPA)

. 1996. Methane Emissions f rom t he Natural Gas I ndustry Volu me 2: Technical Report, Final Report . Gas Research Institute and U.S. Environmental Protection Agency. Washington, DC. June, 1996.
U.S. Environmental Protection Agency ( U.S. EPA)

. 1999. U. S. Methane Emissions 1990

- 2020: Inventories, Projections, and Oppo rtunities for Reductions . Washington, DC, 1999.
U.S. Environmental Protection Agency ( U.S. EPA). 2004. Fact Sheet No. 703: Green Completions. Office of Air and Radiation: Natural Gas Star Program. Washington, DC. September 2004.

U.S. Environmental Protecti on Agency ( U.S. EPA)

. 2011 a

. Lessons Learned: Reduced Emissions Completions for Hydraulically Fractured Gas Wells. Office of Air and Radiation: Natural Gas Star Program . Washington, DC. 2011. Available at http://epa.gov/gasstar/documents/reduced_emissions_ completions.pdf.51



### U.S. Environmental Protection Agency ( U.S. EPA)

. 2011 b

. Oil and Natural Gas Sector: Standards of Performance for Crude Oil and Natural Gas Production, Transmission, and Distribution. Background Technical Support Document for Proposed Stan dards

. July 2011. EPA

- 453/R

- 11002.

U

. S

. Environmental Protection Agency ( U.S. EPA) . 2012 a

. Technical Support Document, Federal Implementation Plan for Oil and Natural Gas Well Production Facilities; Fort Berthold Indian Reservation (Mandan, Hidatsa, and Ar ikara Nations), North Dakota

. Docket Number: EPA

- R08

- OAR

- 2012

- 0479.
U.S. Environmental Protection Agency ( U.S. EPA)

. 2012 b

. Oil and Natural Gas Sector: Standards of Performance for Crude Oil and Natural Gas Production, Transmission, and Distribution. Backg round Supplemental Technical Support Document for Proposed Standards

. April 2012.
U.S. Environmental Protection Agency. (U.S. EPA) 2013. Petroleum and Natural Gas Systems: 2012 Data Summary. Greenhouse Gas Reporting Program . October 2013. ( http://www.epa.g ov/ghgreporting/documents/pdf/2013/documents/SubpartW

- 2012

- Data

Summary.pdf

).
U.S. Environmental Protection Agency (U.S. EPA). 2014 . Inventory of Greenhouse Gas Emissions and Sinks: 1990

- 2012 . Washington, DC. April 2014. (http://www.epa.gov/climatechange/D ownloads/ghgemissions/US

- GHG

- Inventory

- 2014

- Chapter

- 3

- Energy.pdf).A

- 1 

## Appendix A

(ERG, 2013)

Memorandum (Draft) :

E nvironmental Research Group, Inc.

Hydraulically Fractured Oil Well Completions.

October 24, 2013A

- 2

TO : David Hendricks, EC/R Incorporated

FROM : Mike Pring, Eastern Research Group, Inc. (ERG)

Regi Oommen, ERG

DATE : October 24, 2013

SUBJECT : Hydraulically Fractured Oil Well Completions

Eastern Research Group, Inc. (ERG) is currently under cont ract with EC/R Incorporated to provide technical support under EC/R Work Assignment #1

- 11 with U.S. EPA. This memorandum describes ERG’s findings relative to Task 2 of the support effort. Specifically, under this task ERG:



### • Identified wells which were hydraulically fractured in 2011;



### • Determined which of the hydraulically fractured wells completed in 2011 were oil wells;



### • Estimated daily associated gas production from the hydraulically fractured oil wells; and



### • Provided a summary of this informat ion at the national and county level (in Excel spreadsheet format). Wells Hydraulically Fractured in 2011

Starting with the most recent analysis and files delivered by ERG to the U.S. EPA Office of Compliance, ERG queried DI Desktop, a production data base maintained by DrillingInfo, Inc.

covering U.S. oil and natural gas wells, to identify hydraulically fractured oil and gas well completions performed in 2011. This was accomplished using a two

- step process:



### • Identification of wells completed in 201 1;



### • Identification of wells completed using hydraulic fracturing.

Wells completed in 2011 were identified as those wells meeting one of the following criteria: DRAFT MEMORANDUMA

- 3



### • The DI Desktop data for the well indicated it was completed in 2011; or



### • The DI Desktop d ata for the well indicated the well 1 st produced in 2011.

While the DI Desktop database is fairly comprehensive in its geographic and temporal coverage of production data, completion date information can lag behind by a year or more afterwards and is no t universally available for all areas of the country. Therefore, the list of wells with explicit well completion dates of 2011 was supplemented with those wells having a date (month) of 1 st production of either gas or oil in 2011. This methodology is con sistent with the methodology used to estimate well completions in the “Inventory of U.S. Greenhouse Gas Emissions and Sinks: 1990

– 2011 (April 12, 2013)”.

Using this approach, 39,262 conventional and unconventional well completions were identified for 2011.

Once the population of wells completed in 2011 was identified, hydraulically fractured wells were identified as those wells meeting either of the following:



### • Wells completed in a coalbed methane, tight, or shale formation as determined using the DOE EIA formation type crosswalk; or



### • Wells identified in the DI Desktop database as horizontal wells.

The DOE EIA formation type crosswalk used in this analysis may be found in Attachment A. This methodology is consistent with the methodology used to identify the number of hydraulically fractured well completions in the “Inventory of U.S. Greenhouse Gas Emissions and Sinks: 1990

– 2011 (April 12, 2013)”.

Using this approach, 15,979 hydraulically fractured (or unconventional) well completions were i dentified for 2011.

Oil Wells Hydraulically Fractured in 2011

Once the population of hydraulically fractured wells completed in 2011 was identified, each well was then classified as either an oil well or a gas well. Gas wells were defined as those we lls with an average gas to liquids ratio greater than or equal to 12,500 standard cubic feet per barrel over the lifetime of the well, and oil wells were defined as those wells with an average gas to liquids ratio less than 12,500 standard cubic feet per b arrel over the lifetime of the well. Note that the “liquids” quantity used in this analysis does not include produced water. This methodology is consistent with the gas

‐ oil ratio methodology used in the 2012 Oil and Natural Gas Sector NSPS development.

Using this approach, 6,169 hydraulically fractured (or unconventional) oil well completions were identified for 2011.A

- 4

Daily Gas Production of Oil Wells Hydraulically Fractured in 2011

Once the population of hydraulically fractured oil wells complete d in 2011 was identified, the average daily gas production for each well was calculated based on the cumulative gas production from each well during its first year of production. This information was then averaged at the county

- level, as well as at the na tional level. Nationally, the average daily gas production at an oil well that was hydraulically fractured in 2011 was 152 MCF.

Summary Information

Table 1 below presents a state

- level summary of the derived information on hydraulically fractured oil wells completed in 2011. Attachment B contains the same information at the county and national level.

Table 1. Summary of Gas Production at Hydraulically Fractured (or unconventional) Oil Wells

State Number of

Counties Number of

Unconventional Oi l Well Completions Average Associated Gas

Production over the 1 st year (MCF/Day) a
AR 2 19 110.03
CO 12 1057 95.46
FL 1 1 5.81
KS 3 5 0.80
LA 17 24 111.87
MI 4 7 5.58
MS 1 1 0
MT 13 95 31.21
ND 14 1299 138.1 4
NM 6 337 114.89
NY 1 19 0
OH 32 214 4.43
OK 14 89 143.62
PA 5 7 78.38
SD 1 2 42.79
TX 88 2855 284.09
WV 5 11 173.15
WY 14 127 48.62

a Determined by taking the total production from the first 12 months of pro duction and dividing by 365 days. Observations

The analysis conducted under this task was performed in accordance with the procedures described above. With respect to qualitative observations made while implementing these procedures, ERG notes the fo llowing:A

- 5



### • In some instances, the date (month) of 1 st production only included oil production, with no corresponding gas production recorded for that month;



### • In some instances, there were months within the 1 st year of production where there was no produc tion (of oil, gas, or both) recorded for the well;



### • For 415 oil wells hydraulically fractured and completed in 2011, there was no gas production reported for the well during the 1 st year of production.

The net effect of these situations is that the aver age daily gas production values may be skewed low, for example, due to a well being shut in for some period of time after initially being brought into production.

In the case of the 415 wells where there was no gas production reported for the well durin g the 1 st year of production, summary data is presented in Attachment B excluding these records. This data is reflected in the summary sheets indicating “WITHOUT ZERO”. The effect of this differentiation is easily seen in the “UNCONV_OIL_NATIONWIDE” shee t, which shows an average daily gas production of 152 (MCF/day) for all records, and an average daily gas production of 189 (MCF/day) when including only those records with some gas production.A

- 6 Attachment A: DOE EIA Formation Type Crosswalk

(Form ation Crosswalk

- Memo Counts 2012 08 28_From ECR.xlsx)A

- 7

Attachment B: National and County

- level Summary of Average Daily Gas Production from

Hydraulically Fractured Oil Well Completions in 2011

(Task 2 Summary.xlsx)

UNCONVENTIONAL OIL COUNTY WITH ZERO FIPS_ CODE STATE_

ABBR COUNTY_NA

ME NUMBER_UNCONVENTIONAL_OIL_

WELL_COMPLETIONS AVG_ASSOCIATED_GAS _MCF_PER_DAY

05027 AR Columbia 17 220.06

05139 AR Union 2

-

08001 CO Adam s 8 75.81

08005 CO Arapahoe 1 100.28

08013 CO Boulder 4 173.39

08014 CO Broomfield 12 194.15

08043 CO Frem ont 4 15.34

08057 CO Jackson 1 281.19

08069 CO Larimer 14 24.35

08077 CO Mesa 1 0.43

08081 CO Moffa t 2 73.42

08087 CO Morgan 1 14.65

08103 CO Rio Blanco 3 62.57

08123 CO Weld 1006 129.94

12087 FL Monro e 1 5.81

20073 KS Greenwood 1

-

20097 KS Kiowa 1

-

20125 KS Montgomery 3 2.40

22009 LA Avoyelles 2 1.12A

- 8

FIPS_ CODE STATE_

ABBR COUNTY_NA

ME NUMBER_UNCONVENTIONAL_OIL_

WELL_COMPLETIONS AVG_ASSOCIATED_GAS _MCF_PER_DAY

22011 LA Beauregard 1 141.90

22015 LA B ossier 1

-

22017 LA Caddo 2 5.65

22019 LA Calcasieu 1

-

22023 LA Cameron 1 77.58

22027 LA Claiborne 3 1.56

22037 LA East

Feliciana 1 23.45

22047 LA Iberville 1 68.21

22075 LA Plaquemines 1 44.28

22079 LA Rapides 1 6.08

22091 LA St. Helena 1 77.15

22097 LA St. Landry 3 44.34

22101 LA St. Mary 1 10.77

22111 LA Union 1 5.58

22119 LA Webster 1 1,382.30

22127 LA Winn 2 11.78

26075 MI Jackson 3 22.32

26091 MI Lenawee 2

-

26141 MI Presque Isle 1

-

26147 MI St. Clair 1

-

28063 MS Jefferson 1

-

30005 MT Blaine 4

-A

- 9

FIPS_ CODE STATE_

ABBR COUNTY_NA

ME NUMBER_UNCONVENTIONAL_OIL_

WELL_COMPLETIONS AVG_ASSOCIATED_GAS _MCF_PER_DAY

30009 MT Carbon 2 9.60

30021 MT Dawson 1 29.33

30025 MT Fallon 1 138.62

30035 MT Glacier 9 29.37

30065 MT Musselshell 1

-

30069 MT Petroleum 4

-

30073 MT Pondera 1

-

30083 MT Richland 32 94.43

30085 MT Roosevelt 27 102.11

30087 MT Rosebud 2

-

30091 MT Sheridan 10 2.30

30099 MT Teton 1

-

35005 NM Chaves 6 90.22

35015 NM Eddy 206 317.14

35025 NM Lea 121 160.97

35039 NM Rio Arriba 2 57. 02

35043 NM Sandoval 1

-

35045 NM San Juan 1 64.03

36009 NY Cattaraugus 19

-

38007 ND Billings 22 157.36

38009 ND Bottineau 10 2.69

38011 ND Bowman 4 84.54A

- 10

FIPS_ CODE STATE_

ABBR COUNTY_NA

ME NUMBER_UNCONVENTIONAL_OIL_

WELL_COMPLETIONS AVG_ASSOCIATED_GAS _MCF_ PER_DAY

38013 ND Burke 42 83.17

38023 ND Divide 74 144.13

38025 ND Dunn 208 156.73

38033 ND Golden

Valley 3 131.73

38053 ND McKenzie 297 355.17

38055 ND McLean 11 102.95

38061 ND Mountrail 329 176.74

38075 ND Renville 2

-

38087 ND Slope 1 140.16

38089 ND Stark 28 184.08

38105 ND Williams 268 214.53

39005 OH Ashland 23

-

39007 OH Ashtabula 1 20.94

39009 OH Athens 3 2.47

39019 OH Carroll 6 4.31

39029 OH Columbiana 1 6.35

39031 OH Coshocton 8 0.75

39035 OH Cuyahoga 7 12.35

39055 OH Geauga 7 4.13

39067 OH Harrison 3 1.57

39073 OH Hocking 2

-

39075 OH Holmes 14 0.23A

- 11

FIPS_ CODE STATE_

ABBR COUNTY_NA

ME NUMBER_UNCONVENTIONAL_OIL_

WELL_COMPLETIONS A VG_ASSOCIATED_GAS _MCF_PER_DAY

39081 OH Jefferson 6

-

39083 OH Knox 13 1.67

39089 OH Licking 17

-

39093 OH Lorain 1

-

39099 OH Mahoning 3 4.72

39101 OH Marion 1

-

39103 OH Medina 12 0.72

39105 O H Meigs 1 2.08

39111 OH Monroe 13 1.05

39115 OH Morgan 6 0.16

39119 OH Muskingum 9 0.79

39121 OH Noble 1

-

39127 OH Perry 2 0.40

39133 OH Portage 10 10.29

39151 OH Stark 22 6. 70

39153 OH Summit 8 25.92

39155 OH Trumbull 4 19.92

39157 OH Tuscarawas 2 2.52

39167 OH Washington 6 0.35

39169 OH Wayne 1 0.47

39175 OH Wyandot 1 10.79

40011 OK Blaine 4 138.44A

- 12

FIPS_ CODE STATE_

ABBR COUNTY_NA

ME NUMBER_UNCONVENT IONAL_OIL_

WELL_COMPLETIONS AVG_ASSOCIATED_GAS _MCF_PER_DAY

40015 OK Caddo 2

-

40017 OK Canadian 24 59.77

40029 OK Coal 14

-

40039 OK Custer 4 73.81

40043 OK Dewey 5 25.28

40045 OK Ellis 13 82.28

40051 OK Grady 4

-

40069 OK Johnston 1 273.04

40095 OK Marshall 1 758.99

40125 OK Pottawatomi

e 1

-

40129 OK Roger Mills 4 60.26

40149 OK Washita 11 25.78

40151 OK Woods 1 513.08

42019 PA Butler 1 3.00

42083 PA McKean 1 2.85

42123 PA Warren 1 1.17

42125 PA Washington 2 322.21

42129 PA Westmorela

nd 2 62.65

46063 SD Harding 2 42.79

48003 TX Andrews 18 27.20

48009 TX Archer 4 7.96

48013 TX Atascosa 70 119.71A

- 13

FIPS_ CODE STATE_

ABBR COUNTY_NA

ME NU MBER_UNCONVENTIONAL_OIL_

WELL_COMPLETIONS AVG_ASSOCIATED_GAS _MCF_PER_DAY

48033 TX Borden 1

-

48041 TX Brazos 17 88.27

48051 TX Burleson 15 25.89

48055 TX Caldwell 29

-

48077 TX Clay 3 75.75

48079 TX Cochran 3 0.73

48097 TX Cooke 99 297.95

48103 TX Crane 19 110.50

48105 TX Crockett 20 151.12

48109 TX Culberson 1 2,500.75

48123 TX DeWitt 145 1,332.05

48127 TX Dimmit 322 379.76

48135 TX Ector 15 12.91

48149 TX Fayette 13 79.71

48151 TX Fisher 2 1.68

48163 TX Frio 72 105.01

48165 TX Gaines 1 3.92

48169 TX Garza 1

-

48173 TX Glasscock 19 272.15

48177 TX Gonzales 207 98.80

48181 TX Grayson 4 367.12

48183 TX Gregg 3 23.02A

- 14

FIPS_ CODE STATE_

ABBR COUNTY_NA

ME NUMBER_UNC ONVENTIONAL_OIL_

WELL_COMPLETIONS AVG_ASSOCIATED_GAS _MCF_PER_DAY

48185 TX Grimes 7 586.87

48187 TX Guadalupe 2

-

48195 TX Hansford 3 9 3.42

48197 TX Hardeman 2 74.00

48201 TX Harris 1 1.84

48203 TX Harrison 2 13.53

48211 TX Hemphill 15 390.47

48225 TX Houston 1 127.46

48235 TX Irion 87 112.45

48237 TX Jack 22 122.06

48241 TX Jasper 2 1,387.63

48255 TX Karnes 309 388.35

48263 TX Kent 1

-

48273 TX Kleberg 2 33.10

48283 TX La Salle 216 185. 29

48285 TX Lavaca 13 83.04

48287 TX Lee 5 25.93

48289 TX Leon 19 61.86

48295 TX Lipscomb 84 403.67

48297 TX Live Oak 89 731.54

48301 TX Loving 28 276.40

48311 TX McMullen 130 276.52A

- 15

FIPS_ CODE STATE_

ABBR COUNTY_NA

ME NUMBER_UNCONVENTIONAL_OIL_

W ELL_COMPLETIONS AVG_ASSOCIATED_GAS _MCF_PER_DAY

48313 TX Madison 21 173.35

48317 TX Martin 1 50.01

48323 TX Maverick 23 110.15

48329 TX Midland 1 12.33

48331 TX Milam 3 34.19

48337 TX Montague 119 362.22

48351 TX Newton 2 2,539.85

48353 TX Nolan 24 20.97

48355 TX Nueces 3 1,746.66

48357 TX Ochiltree 82 261.41

48363 TX Palo Pinto 3 244.63

48365 TX Panola 2 220.47

48367 TX Parker 1 20.61

48371 TX Pecos 8 42.56

48373 TX Polk 4 1,394.01

48383 TX Reagan 15 66.05

48389 TX Reeves 39 184.15

48393 TX Roberts 21 445.09

48395 TX Robertson 15 22.76

48401 TX Rusk 3 5.40

48405 TX San

Augustine 1 1,052.92

48413 TX Schleicher 1 171.38A

- 16

FIPS_ CODE STATE_

ABBR COUNTY_NA

ME NUMBER_UNCONVENTIONAL_OIL_

WELL_COMPLETIONS AVG_ASSOCIAT ED_GAS _MCF_PER_DAY

48415 TX Scurry 5 84.33

48417 TX Shackelford 1

-

48425 TX Somervell 2 1.29

48429 TX Stephens 2 27.98

48433 TX Stonewall 18 0.61

48439 TX Tarrant 1 60.16

48449 TX Titus 1

-

48457 TX Tyler 2 1,099.59

48459 TX Upshur 1 49.13

48461 TX Upton 12 3.26

48475 TX Ward 73 375.79

48477 TX Washington 1 276.18

48479 TX Webb 44 874.17

48483 TX Wheeler 60 965.66

48493 TX Wilson 33 36.46

48495 TX Winkler 7 137.90

48497 TX Wise 3 342.57

48503 TX Young 2

-

48507 TX Zavala 52 26.70

54001 WV Barbour 1 1.05

54051 WV Marshall 1 782.02

54053 WV Mason 1 1.40A

- 17

FIPS_ CODE STATE_

ABBR COUNTY_NA

ME NUMBER_UNCONVENTIONAL_OIL_

WELL_COMPLETIONS AVG_ASSOCIATED_GAS _MCF_PER_DAY

54085 WV Ritchie 1

-

54103 WV Wetzel 7 81.30

56003 WY Big Horn 1 10.12

56005 WY Campbell 29 282.44

56007 WY Carbon 2 3.52

56009 WY Converse 45 190.09

56013 WY Fremont 3 2.17

56015 WY Goshen 4 11.56

56017 WY Hot Springs 1 0.11

56019 WY Johnson 2 29.93

56021 WY Laramie 22 56.63

56025 WY Natrona 2 0.02

56027 WY Niobrara 2 20.77

56029 WY Park 3 5.60

56031 WY Platte 2 8.15

56037 WY Sweetwater 9 59.59A

- 18

UNCONVENTONAL OIL COUTTY WITHOUT ZERO FIPS_CO DE STATE_A

BBR COUNTY_

NAME NUMBER_UNCONVENTIONAL_OIL_

WELL_COMPLETIONS AVG_ASSOCIATED_GAS_ MCF_PER_DAY

05027 AR Columbia 17 220.06

080 01 CO Adams 8 75.81

08005 CO Arapahoe 1 100.28

08013 CO Boulder 4 173.39

08014 CO Broomfield 12 194 .15

08043 CO Fremont 4 15.34

08057 CO Jackson 1 281.19

08069 CO Larimer 14 24.35

08077 CO Mesa 1 0.43

08081 CO Moffat 2 73.42

08087 CO Morgan 1 14.65

08103 CO Rio Blanco 1 187.70

08123 CO Weld 1000 130.72

12087 FL Monroe 1 5.81

20125 KS Montgomery 3 2.40

22009 LA Avoyelles 1 2.24

22011 LA Beauregard 1 141.90

22017 LA Caddo 1 11.31

22023 LA Cameron 1 77.58

22027 LA Claiborne 1 4.67

22037 LA E ast Feliciana 1 23.45

22047 LA Iberville 1 68.21A

- 19

FIPS_CO DE STATE_A

BBR COUNTY_

NAME NUMBER_UNCONVENTIONAL_OIL_

WELL_COMPLETIONS AVG_ASSOCIATED_GAS_ MCF_PER_DAY

22075 LA Plaqu emines 1 44.28

22079 LA Rapides 1 6.08

22091 LA St. Helena 1 77.15

22097 LA St. Landry 2 66.51

22101 LA St. Mary 1 10.77

22111 LA Union 1 5.58

22119 LA Webster 1 1,382.30

22127 LA Winn 2 11.78

26075 MI Jackson 2 33.48

30009 MT Carbon 1 19.19

30021 MT Dawson 1 29.33

30025 MT Fallon 1 138.62

30035 MT Glacier 7 37.76

30083 MT Richland 30 100.73

30085 MT Roosevelt 27 102.11

30091 MT Sheridan 7 3.28

35005 NM Chaves 5 108.26

35015 NM Eddy 205 318.68

35025 NM Lea 112 173.90

35039 NM Rio Arriba 2 57.02

35045 NM San Juan 1 64.03

38007 ND Billings 22 157.36A

- 20

FIPS_CO DE STATE_A

BBR COUNTY_

NAME NUMBER_UNCONVENTIONAL_OIL_

WELL_COMPLETIONS AV G_ASSOCIATED_GAS_ MCF_PER_DAY

38009 ND Bottineau 5 5.38

38011 ND Bowman 4 84.54

38013 ND Burke 42 83.17

38023 ND Divide 74 144.13

38025 ND Dunn 208 156.73

38033 ND Golden

Valley 3 131.73

38053 ND McKenzie 295 357.58

38055 ND McL ean 11 102.95

38061 ND Mountrail 329 176.74

38087 ND Slope 1 140.16

38089 ND Stark 28 184.08

38105 N D Williams 268 214.53

39007 OH Ashtabula 1 20.94

39009 OH Athens 2 3.70

39019 OH Carroll 4 6.46

39029 OH Columbiana 1 6.35

39031 OH Coshocton 3 2.00

39035 OH Cuyahoga 7 12.35

39055 OH Geauga 7 4.13

39067 OH Harrison 2 2.36

39075 OH Holmes 4 0.82

39083 OH Knox 8 2.71A

- 21

FIPS_CO DE STATE_A

BBR COUNT Y_

NAME NUMBER_UNCONVENTIONAL_OIL_

WELL_COMPLETIONS AVG_ASSOCIATED_GAS_ MCF_PER_DAY

39099 OH Mahoning 2 7.08

39103 OH Medina 2 4.31

39105 OH Meigs 1 2.08

39111 OH Monroe 8 1.71

39115 OH Morgan 3 0.32

39119 OH Muskingum 4 1.78

39127 OH Perry 1 0.79

39133 OH Portage 9 11.43

39151 OH Stark 17 8.67

39153 OH Summit 7 29.62

39155 OH Trum bull 4 19.92

39157 OH Tuscarawas 1 5.04

39167 OH Washington 2 1.04

39169 OH Wayne 1 0.47

39175 OH Wyandot 1 10.79

40011 OK Blaine 4 138.44

40017 OK Canadian 8 179.30

40039 OK Custer 2 147.61

40043 OK Dewey 2 63.20

40045 OK Ellis 9 118.85

40069 OK Johnston 1 273.04

40095 OK Marshall 1 758.99A

- 22

FIPS_CO DE STATE_A

BBR COUNTY_

NAME NUMBER_UNCONVENTIONAL_OIL_

WELL_COMPLETIONS AVG_ASSOCIATED_GAS_ MCF_PER_DAY

40129 OK Roger Mills 3 80.35

40149 OK Washita 1 283. 55

40151 OK Woods 1 513.08

42019 PA Butler 1 3.00

42083 PA McKean 1 2.85

42123 PA Warren 1 1.17

42125 PA Washington 2 322.21

42129 PA Westmorelan

d 2 62.65

46063 SD Harding 1 85.59

48003 TX Andrews 16 30.60

48009 TX Archer 1 31.86

48013 TX Atascosa 69 121.44

48041 TX Brazos 17 88.27

48051 TX Burleson 6 64.72

48077 TX Clay 3 75.75

48079 TX Cochran 3 0.73

48097 TX Cooke 99 297.95

48103 TX Crane 1 9 110.50

48105 TX Crockett 19 159.07

48109 TX Culberson 1 2,500.75

48123 TX DeWitt 143 1,350.68

48127 TX D immit 317 385.75A

- 23

FIPS_CO DE STATE_A

BBR COUNTY_

NAME NUMBER_UNCONVENTIONAL_OIL_

WELL_COMPLETIONS AVG_ASSOCIATED_GAS_ MCF_PER_DAY

48135 TX Ector 15 12.91

48149 TX Fayette 12 86.35

48151 TX Fisher 2 1.68

48163 TX Frio 58 130.36

48165 TX Gaines 1 3.92

48173 TX Glassco ck 19 272.15

48177 TX Gonzales 196 104.35

48181 TX Grayson 3 489.50

48183 TX Gregg 3 23.02

48185 TX Grimes 7 586.87

48195 TX Hansford 3 93.42

48197 TX Hardeman 1 147.99

48201 TX Harris 1 1.84

48203 TX Harrison 1 27.06

48211 TX Hemphill 15 390.47

48225 TX Houston 1 127.46

48235 TX Irion 87 112.45

48237 TX Jack 22 122.06

48241 TX Jasper 2 1,387.63

48255 TX Karnes 303 396.04

48273 TX Kleberg 2 33.10

48283 TX La Salle 214 187.02A

- 24

FIPS_CO DE STATE_A

BBR COUNTY_

NAME NUMBER_UNCONVENTIONAL_OIL_

WELL_COMPLETIONS AVG_ASSOCIATED_GAS_ MCF_PER_DAY

48285 TX Lavaca 13 83.04

48287 TX Lee 3 43.21

48289 TX Leon 16 73.46

48295 TX Lipscomb 82 413.52

48297 TX Live Oak 89 7 31.54

48301 TX Loving 26 297.66

48311 TX McMullen 125 287.58

48313 TX Madison 20 182.01

48317 TX Martin 1 50.01

48323 TX Maverick 18 140.75

48329 TX Midland 1 12.33

48331 TX Milam 2 51.29

48337 TX Montague 115 374.82

48351 TX Newton 2 2,539.85

48353 TX Nolan 22 22.87

48355 TX Nueces 3 1,746.66

48357 TX Ochiltree 82 261.41

48363 TX Palo Pinto 3 244.63

48365 TX Panola 2 220.47

48367 TX Parker 1 20.61

48371 TX Pecos 8 42.56

48373 TX Polk 4 1,394.01A

- 25

FIPS_CO DE STATE_A

BBR COUNTY_

NAME NUMBER_UNCONVENTIONAL_OIL_

WELL_COMPLETIONS AVG_ASSOCIATED_GAS_ MCF_PER_DAY

48383 TX Reagan 14 70.77

48389 TX Reeves 37 194.11

48393 TX Roberts 21 445.09

48395 TX Robertson 12 28.45

48401 TX Rusk 1 16.21

48405 TX San

Augustine 1 1,052.92

48413 TX Schleicher 1 171.38

48415 TX Scurry 5 84.33

48425 TX Somervell 2 1.29

48429 TX Stephens 2 27.98

48433 TX Stonewall 15 0.74

48439 TX Tarrant 1 60.16

484 57 TX Tyler 2 1,099.59

48459 TX Upshur 1 49.13

48461 TX Upton 12 3.26

48475 TX Ward 73 375.79

4 8477 TX Washington 1 276.18

48479 TX Webb 44 874.17

48483 TX Wheeler 59 982.03

48493 TX Wilson 28 4 2.98

48495 TX Winkler 7 137.90

48497 TX Wise 3 342.57A

- 26

FIPS_CO DE STATE_A

BBR COUNTY_

NAME NUMBER_UNCONVENTIONAL_OIL_

WELL_COMPLETIONS AVG_ASSOCIATED_GAS_ MCF_PER_DAY

48507 TX Zava la 45 30.86

54001 WV Barbour 1 1.05

54051 WV Marshall 1 782.02

54053 WV Mason 1 1.40

54 103 WV Wetzel 7 81.30

56003 WY Big Horn 1 10.12

56005 WY Campbell 27 303.36

56007 WY Carbon 1 7.03

56009 WY Converse 45 190.09

56013 WY Fremont 1 6.52

56015 WY Goshen 4 11.56

56017 WY Hot Springs 1 0.11

56019 WY Johnson 2 29.93

56021 WY Laramie 21 59.33

56025 WY Natrona 1 0.03

56027 WY Niobrara 1 41.54

56029 WY Park 3 5.60

56031 WY Platte 2 8.15

56037 WY Sweetwater 8 67.04A

- 27 UNCONVEN TIONAL OIL NATIONWIDE NATIONWIDE UNCONVENTIONAL OIL WELL COMPLETIONS (WITH ZERO)

GEOGRAPHIC NUMBER_OF_

STATES NUMBER_OF_

COUNTIES NUMBER_UNCONVENTIONAL_OI

L_WELL_COMPLETIONS AVG_ASSOCIATED_GAS_ MCF_PER_DAY

NATIONWIDE 18 233 6169 152.19

NATIONWIDE UNCONVENTIONAL OIL WELL COMPLETIONS (WITHOUT ZERO)

GEOGRAPHIC NUMBER_OF_

STATES NUMBER_OF_

COUNTIES NUMBER_UNCONVENTIONAL_OI

L_WELL_COMPLETIONS AVG_ASSOCIATED_GAS_ MCF_PER_DAY

NATIONWIDE 16 195 5754 189.35