773 San Marin Drive, Suite 2115, Novato, CA 94998 415.899.0700 

ENVIRON International Corporation 

DEVELOPMENT OF 2010 OIL AND GAS EMISSIONS PROJECTIONS 

FOR THE DENVER-JULESBURG BASIN 

Prepared for 

Colorado Department of Public Health and 

Environment Air Pollution Control Division 

Prepared by 

Amnon Bar-Ilan 

John Grant 

Ron Friesen 

Alison K. Pollack 

ENVIRON International Corporation 

773 San Marin Drive, Suite 2115 

Novato, CA 94998 

Doug Henderer 

Daniel Pring 

Buys & Associates 

300 E. Mineral Ave., Suite 10 

Littleton, CO 80122 

Andrew Bremner 

Independent Petroleum Association of Mountain States (IPAMS) 

410 17th Street, Suite 1920 

Denver, CO 80202 

Phase III Oil & Gas Emissions Inventory Project 

http://www.wrapair.org/forums/ssjf/documents/eictts/oilgas.html 

April 30, 2008 
April 2008 

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TABLE OF CONTENTS 

Page 

INTRODUCTION..........................................................................................................................1 

GEOGRAPHIC GROUPING.......................................................................................................1 

PARAMETERS PROJECTED ....................................................................................................2 

PROJECTION METHODOLOGIES FOR 

GEOGRAPHIC GROUPINGS.....................................................................................................4 

Weld County ........................................................................................................................4 

Yuma County.......................................................................................................................8 

All Other Counties .............................................................................................................12 

SCALING FACTOR DEVELOPMENT AND 

UNCONTROLLED 2010 EMISSIONS .....................................................................................15 

Weld and Yuma County.....................................................................................................15 

All Other Counties in the D-J Basin ..................................................................................16 

CONTROLLED 2010 EMISSIONS...........................................................................................17 

SUMMARY RESULTS...............................................................................................................18 

TABLES 

Table 1 Scaling parameter for each oil and gas source category considered in this 

inventory ........................................................................................................................2 

Table 2 Scaling factors for the four parameters used in the projection analysis for the 

three geographic groupings..........................................................................................17 

Table 3 Summary of federal and state “on-the-books” regulations affecting the oil and 

gas source categories considered in this inventory......................................................17 

Table 4 2010 emissions of all criteria pollutants by county for the D-J Basin.........................21 

Table 5 2010 NOx emissions [ton/yr] by county and by source category for the D-J 

Basin ............................................................................................................................22 

Table 6 2010 VOC emissions [ton/yr] by county and by source category for the D-J 

Basin. ...........................................................................................................................23 

FIGURES 

Figure 1 Gas production historical data for Weld County (from the IHS database)....................4 

Figure 2 Oil production historical data for Weld County (from the IHS database).....................5 

Figure 3 Well count historical data for Weld County (from the IHS database)...........................6 

Figure 4 Spud count historical data for Weld County (from the IHS database) ..........................7 
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Figure 5 Gas production historical data for Yuma County (from the IHS database)..................8 

Figure 6 Oil production historical data for Yuma County (from the IHS database)....................9 

Figure 7 Well count historical data for Yuma County (from the IHS database)........................10 

Figure 8 Spud count historical data for Yuma County (from the IHS database) .......................11 

Figure 9 Gas production historical data for all other counties in the D-J Basin combined 

(from the IHS database)...............................................................................................12 

Figure 10 Oil production historical data for all other counties in the D-J Basin combined 

(from the IHS database)...............................................................................................13 

Figure 11 Well count historical data for all other counties in the D-J Basin combined 

(from the IHS database)...............................................................................................14 

Figure 12 Spud count historical data for all other counties in the D-J Basin combined 

(from the IHS database)...............................................................................................15 

Figure 13 2010 NOx emissions by source category and by county in the D-J Basin ..................19 

Figure 14 2010 VOC emissions by source category and by county in the D-J Basin.................19 

Figure 15 2010 NOx emissions proportional contributions by source category in the DJ 

Basin ............................................................................................................................20 

Figure 16 2010 VOC emissions proportional contributions by source category in the DJ 

Basin ............................................................................................................................20 
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INTRODUCTION 

This document outlines the projection methodologies used in generating the 2010 model-ready 

emissions from oil and gas sources in the Denver-Julesburg (D-J) Basin to be used in the 

upcoming Denver metropolitan-area ozone SIP modeling. These methodologies will use as a 

starting point the 2006 baseline D-J Basin oil and gas emissions inventory as approved by 

CDPHE. 

This methodology description is broken down into subsections which describe: 

• Geographic grouping of data – regional differences in production or activity are factored 

into the projection methodology by geographic region 

• Projected parameters – four basic parameters are projected forward to 2010 for purposes 

of developing scaling factors: well counts, spud counts, gas production and oil production 

• Scaling factors and developing uncontrolled emissions projections – the projected 

parameters are used to develop scaling factors (incorporating geographic groupings), and 

these scaling factors are applied to the 2006 baseline emissions 

• Application of “on-the-books” regulations and control measures – existing regulations are 

summarized for their impacts on the future year emissions and applied to adjust the 2010 

inventory. 

Projections for years beyond 2010 (not addressed in this methodology) will likely include 

additional parameters and will be based on these 2010 projections as the start year. 

Following the discussion of the methodology, the results of the 2010 emissions projections for 

the D-J Basin are presented in graphical and tabular formats. 

GEOGRAPHIC GROUPING

The projections for 2010 have been conducted separately for 3 geographic groupings in the D-J 

Basin: 

1. Weld County 

2. Yuma County 

3. All other counties in the D-J Basin combined 

The reason for conducting this grouping is that the majority of 2006 production, well counts and 

spud (drilling event) counts occur in Weld and Yuma County. Weld and Yuma Counties 

combined represent 94% and 87% of all gas and oil production respectively in the D-J Basin in 

2006. Weld and Yuma Counties combined represent 87% and 95% of all wells and spuds 

respectively in the D-J Basin in 2006. Because oil and gas exploration and production activities 

differ significantly in Weld and Yuma Counties, these two counties are each treated separately. 
April 2008 

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PARAMETERS PROJECTED 

The 2010 projections for oil and gas emissions in the D-J Basin rely on scaling 4 parameters: 

• Well counts 

• Spud counts 

• Gas production 

• Oil production 

These four parameters are considered because each parameter applies to the emissions 

projections of one or more source categories. The mapping of source category to projection 

parameter is shown below in Table 1. 

Table 1. Scaling parameter for each oil and gas source category considered in this inventory. 

Source SCC Description 

Projection 

Parameter 

Unpermitted 2310000100 Heaters well count 

Unpermitted 2310000220 Drill rigs spud count 

Unpermitted 2310000230 Workover rigs well count 

Unpermitted 2310000300 Pneumatic devices well count 

Unpermitted 2310000700 Fugitives well count 

Unpermitted 2310000800 Truck loading of condensate liquid oil production 

Unpermitted 2310001610 Venting - initial completions spud count 

Unpermitted 2310001620 Venting - recompletions spud count 

Unpermitted 2310001630 Venting - blowdowns gas production 

Unpermitted 2310002210 Small condensate tanks oil production 

Regulation 7 2310002220 Large condensate tanks oil production 

Unpermitted 2310002250 Condensate tank flaring oil production 

Unpermitted 2310003100 Exempt engines well count 

Unpermitted 2310003200 Pneumatic pumps well count 

Unpermitted 2310003300 Spills oil production 

Unpermitted 2310003400 Water tank losses oil production 

APENS 20200201 Compressor Engines gas production 

APENS 20200202 Compressor Engines gas production 

APENS 20200203 Compressor Engines gas production 

APENS 20200209 Compressor Engines gas production 

APENS 20200252 Compressor Engines gas production 

APENS 20200253 Compressor Engines gas production 

APENS 20200254 Compressor Engines gas production 

APENS 31000101 Permitted Fugitives oil production 

APENS 31000102 Oil Production, Miscellaneous Well: General oil production 

APENS 31000123 Oil Production, Well Casing Vents oil production 

APENS 31000129 Oil Production, Gas/Liquid Separation oil production 

APENS 31000130 Oil Production, Fugitives: Compressor Seals oil production 

APENS 31000132 Oil Production, Atmospheric Wash Tank: Flashing Loss oil production 

APENS 31000199 Oil Production, Processing Operations: Not Classified oil production 

APENS 31000201 

Natural Gas Production, Gas Sweetening: Amine 

Process gas production 

APENS 31000202 Natural Gas Production, Gas Stripping Operations gas production 
April 2008 

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Source SCC Description 

Projection 

Parameter 

APENS 31000203 Compressor Engines gas production 

APENS 31000205 Natural Gas Production, Flares gas production 

APENS 31000207 Permitted Fugitives gas production 

APENS 31000209 

Natural Gas Production, Incinerators Burning Waste 

Gas or Augmented Waste Gas gas production 

APENS 31000215 

Natural Gas Production, Flares Combusting Gases 

>1000 BTU/scf gas production 

APENS 31000216 

Natural Gas Production, Flares Combusting Gases 

<1000 BTU/scf gas production 

APENS 31000220 Natural Gas Production, All Equipt Leak Fugitives gas production 

APENS 31000225 Natural Gas Production, Compressor Seals gas production 

APENS 31000226 Natural Gas Production, Flanges and Connections gas production 

APENS 31000227 Glycol Dehydrator oil production 

APENS 31000228 Glycol Dehydrator oil production 

APENS 31000229 Natural Gas Production, Gathering Lines gas production 

APENS 31000230 Natural Gas Production, Hydrocarbon Skimmer gas production 

APENS 31000299 Natural Gas Production, Other Not Classified gas production 

APENS 31000301 Glycol Dehydrator gas production 

APENS 31000302 Glycol Dehydrator gas production 

APENS 31000303 Glycol Dehydrator gas production 

APENS 31000304 Glycol Dehydrator gas production 

APENS 31000305 

Natural Gas Processing Facilities, Gas Sweeting: Amine 

Process gas production 

APENS 31000306 Natural Gas Processing Facilities, Process Valves gas production 

APENS 31000307 Natural Gas Processing Facilities, Relief Valves gas production 

APENS 31000309 Natural Gas Processing Facilities, Compressor Seals gas production 

APENS 31000310 Natural Gas Processing Facilities, Pump Seals gas production 

APENS 31000311 

Natural Gas Processing Facilities, Flanges and 

Connections gas production 

APENS 31000404 Process Heaters well count 

APENS 31000405 Process Heaters well count 

APENS 31000406 Process Heaters well count 

APENS 31000502 Liquid Separator well count 

APENS 31088801 Permitted Fugitives gas production 

APENS 31088802 Permitted Fugitives gas production 

APENS 31088803 Permitted Fugitives gas production 

APENS 31088804 Permitted Fugitives gas production 

APENS 31088805 Permitted Fugitives gas production 

APENS 31088811 Permitted Fugitives gas production 

APENS 40400301 Tank Losses oil production 

APENS 40400302 Tank Losses oil production 

APENS 40400304 Tank Losses oil production 

APENS 40400305 Tank Losses oil production 

APENS 40400311 Tank Losses oil production 

APENS 40400312 Tank Losses oil production 

APENS 40400315 Tank Losses oil production 

APENS 40400322 Tank Losses oil production 

APENS 40400332 Tank Losses oil production 
April 2008 

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PROJECTION METHODOLOGIES FOR GEOGRAPHIC GROUPINGS 

For each geographic grouping, the methodology for obtaining the 2010 value of each projection 

parameter (well count, spud count, oil production and gas production) is described below. In 

general, the methodologies were developed by obtaining the historical data for the parameter in 

the geographic grouping using the IHS database, and projecting a trend line forward from 2006 

to 2010. The IHS database is a tool to query COGCC data, and previous work has confirmed 

that IHS data is consistent with COGCC’s data. In some cases, a different methodology was 

applied as noted below. 

Weld County 

Gas Production - Gas production in Weld County has been plotted for the years 1970 – 2006 

below in Figure 1. 

0

50,000,000

100,000,000

150,000,000

200,000,000

250,000,000

1970 1975 1980 1985 1990 1995 2000 2005

Year

Gas Production [mcf]

Figure 1. Gas production historical data for Weld County (from the IHS database). 

Because production activity differed greatly in Weld County in the years prior to 1997 from what 

has occurred from 1997 – 2006, only the period 1997 – 2006 is considered in this analysis. 

During this period, gas production peaked in 2004 and has been declining from 2004 – 2006. 

This decline is the result of the depletion of the J Sands formation. New drilling in the Codell 

formation is producing significantly higher oil production. However, the major companies in the 

D-J Basin have indicated that they intend to continue drilling activities in Weld County and 

expect gas production from their operations to continue to grow at 5% per year1. 

 

1

 Data provided by Anadarko Petroleum Corp. and Noble Energy Inc. 
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Based on this information, the methodology used to estimate 2010 gas production in Weld 

County was to grow 2006 gas production in the county by 5% per year for the years 2006 – 

2010. 

Oil Production – Oil production in Weld County has been plotted for the years 1970 – 2006 

below in Figure 2. 

0

2,000,000

4,000,000

6,000,000

8,000,000

10,000,000

12,000,000

14,000,000

1970 1975 1980 1985 1990 1995 2000 2005

Year

Oil Production [bbl]

Figure 2. Oil production historical data for Weld County (from the IHS database). 

Similarly to gas production, oil activity has differed greatly from 1999 – 2006 than from past 

activity before 1999. Data from 1999 – 2006 is considered in this projection methodology. 

Based on information from the major production companies in Weld County2

, it was assumed 

conservatively that growth in oil production would continue following the trend observed from 

1999 – 2006. A linear curve was best fit to the 1999 – 2006 oil production data, and this curve 

was extrapolated to 2010. 

 

2

 Data provided by Anadarko Petroleum Corp. and Noble Energy Inc. 
April 2008 

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Well Count – Well counts in Weld County have been plotted for the years 1970 – 2006 below in 

Figure 3. 

0

2000

4000

6000

8000

10000

12000

14000

1970 1975 1980 1985 1990 1995 2000 2005

Year

Well Count

Figure 3. Well count historical data for Weld County (from the IHS database). 

Based on the historical data shown in Figure 3, a second order curve was best fit to the 1999 – 

2006 well count data for Weld County and extrapolated to 2010. 
April 2008 

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Spud Count – Spud counts in Weld County have been plotted for the years 1970 – 2006 below in 

Figure 4. 

0

200

400

600

800

1000

1200

1970 1975 1980 1985 1990 1995 2000 2005

Year

Number of Spuds

Figure 4. Spud count historical data for Weld County (from the IHS database). 

Based on the increased activity from 1999 – 2006 as described above, only this data was 

considered for purposes of projecting Weld County spud counts. A linear curve was best fit to 

the spud count data from 1999 – 2006 and extrapolated to 2010. For each year between 2006 – 

2010, the spud count was evaluated and totaled and this total was compared to the 2010 well 

count projection to assess whether the total drilling activity added to the 2006 existing well count 

matched reasonably well with the prediction for 2010 well count. It was found that spud count 

projections matched reasonably well with well count projections. 
April 2008 

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Yuma County 

Gas Production - Gas production in Yuma County has been plotted for the years 1970 – 2006 

below in Figure 5. 

0

5,000,000

10,000,000

15,000,000

20,000,000

25,000,000

30,000,000

35,000,000

40,000,000

1970 1975 1980 1985 1990 1995 2000 2005

Year

Gas Production [mcf]

Figure 5. Gas production historical data for Yuma County (from the IHS database). 

Production of gas in Yuma County has accelerated recently, from 2004 – 2006 due to increased 

activity in this area. Therefore gas production data from 2004 – 2006 was used for purposes of 

projecting gas production to 2010. A linear curve was best fit to the gas production data from 

2004 – 2006 and extrapolated to 2010. This is likely to conservatively overestimate the gas 

production in this county for 2010. 
April 2008 

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Oil Production - Oil production in Yuma County has been plotted for the years 1970 – 2006 

below in Figure 6. 

0

200

400

600

800

1,000

1,200

1,400

1,600

1970 1975 1980 1985 1990 1995 2000 2005

Year

Oil Production [bbl]

Figure 6. Oil production historical data for Yuma County (from the IHS database). 

Yuma County has had little or no oil production during the period 1970 – 2006, and no oil 

production from 1996 – 2006. It was assumed that there is no oil production in Yuma County in 

2010. 
April 2008 

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Well Count – Well counts in Yuma County have been plotted for the years 1970 – 2006 below in 

Figure 7. 

0

500

1000

1500

2000

2500

3000

3500

1970 1975 1980 1985 1990 1995 2000 2005

Year

Well Count

Figure 7. Well count historical data for Yuma County (from the IHS database). 

Due to the increased recent activity in Yuma County as described above, well count data from 

2004 – 2006 was used to project 2010 well counts. A linear curve was best fit to the 2004 – 

2006 well count data and projected to 2010. 
April 2008 

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Spud Count – Spud counts in Yuma County have been plotted for the years 1970 – 2006 below 

in Figure 8. 

0

100

200

300

400

500

600

700

1970 1975 1980 1985 1990 1995 2000 2005

Year

Number of Spuds

Figure 8. Spud count historical data for Yuma County (from the IHS database). 

There has been a substantial increase in the number of annual spuds in Yuma County from 2004 

– 2005, however there were fewer spuds recorded in 2006. Based on information from the major 

producing companies3 this is likely due to the lack of availability of drilling equipment in Yuma 

County as activity in other major basins in Colorado and other states is utilizing much of the 

available drilling capacity. Therefore the number of spuds was projected to remain constant 

from 2006 – 2010. 

 

3

 Data provided by Anadarko Petroleum Corp. and Noble Energy Inc. 
April 2008 

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All Other Counties 

Gas Production - Gas production in all other D-J Basin counties combined has been plotted for 

the years 1970 – 2006 below in Figure 9. 

0

5,000,000

10,000,000

15,000,000

20,000,000

25,000,000

30,000,000

35,000,000

40,000,000

1970 1975 1980 1985 1990 1995 2000 2005

Year

Gas Production [mcf]

Figure 9. Gas production historical data for all other counties in the D-J Basin combined (from 

the IHS database). 

Figure 9 shows that from 1992 – 2006 gas production has declined in this geographic grouping. 

An exponential curve was best fit to the gas production data in all other counties combined in the 

years 1992 – 2006, and extrapolated to 2010. 
April 2008 

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Oil Production – Oil production in all other D-J Basin counties combined has been plotted for 

the years 1970 – 2006 below in Figure 10. 

0

1,000,000

2,000,000

3,000,000

4,000,000

5,000,000

6,000,000

7,000,000

8,000,000

9,000,000

10,000,000

1970 1975 1980 1985 1990 1995 2000 2005

Year

Oil Production [bbl]

Figure 10. Oil production historical data for all other counties in the D-J Basin combined (from 

the IHS database). 

Figure 10 shows that from 1985 – 2006 oil production has declined in this geographic grouping. 

An exponential curve was best fit to the oil production data in all other counties combined in the 

years 1985 – 2006, and extrapolated to 2010. 
April 2008 

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Well Count – Well counts in all other D-J Basin counties combined have been plotted for the 

years 1970 – 2006 below in Figure 11. 

0

500

1,000

1,500

2,000

2,500

1970 1975 1980 1985 1990 1995 2000 2005

Year

Well Count

Figure 11. Well count historical data for all other counties in the D-J Basin combined (from the 

IHS database).

Well counts in the combined other counties in D-J Basin is primarily driven by activity in Adams 

county, which borders the large oil and gas development area in Weld County. As described 

above, a significant increase in activity in this area has been observed since 1999. Based on this 

information, a linear curve was best fit to the well count data for all other counties in the D-J 

Basin combined for the years 1999 – 2006, and extrapolated to 2010. 
April 2008 

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Spud Count – Spud counts in all other D-J Basin counties combined have been plotted for the 

years 1970 – 2006 below in Figure 12. 

0

100

200

300

400

500

600

700

800

900

1970 1975 1980 1985 1990 1995 2000 2005

Year

Number of Spuds

Figure 12. Spud count historical data for all other counties in the D-J Basin combined (from the 

IHS database). 

Figure 12 shows that from 1985 – 2006 spud counts have declined in this geographic grouping. 

An exponential curve was best fit to the spud count data in all other counties combined in the 

years 1985 – 2006, and extrapolated to 2010. 

SCALING FACTOR DEVELOPMENT AND UNCONTROLLED 2010 EMISSIONS 

Scaling factors were generated for each geographic grouping for each parameter considered here: 

gas production, oil production, well count and spud count. The ratio of the value of each of these 

parameters in each geographic grouping in 2010 to their values in 2006 is the scaling factor for 

that parameter for purposes of this projection. A more detailed description is given below for 

each geographic grouping. 

Weld County and Yuma County 

The projected 2010 values of each of the four parameters for each of these two counties were 

ratioed to the value of the respective parameter in 2006, following Equation (1): 

Equation (1) 

2006

2010

W

W fi =
April 2008 

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where: 

fi is the scaling factor for either Weld or Yuma County for parameter i (gas production, oil 

production, well count or spud count) 

W2006 is the value of parameter i in 2006 

W2010 is the projected value of parameter i in 2010 

All Other Counties in the D-J Basin 

Because all other counties were combined for purposes of projecting gas production, oil 

production, well count, and spud count, the projected parameters were apportioned to each 

county in this grouping based on the 2006 fractions of that county’s gas production, oil 

production, well count or spud count. The scaling factors for each county in this grouping are 

estimated according to Equation (2): 

Equation (2) ⎟

⎠

⎞ ⎜

⎝

⎛ = ×

2006

2010 , Q

Q f c i i county

where: 

fi is the scaling factor for each county in the “other counties” grouping for parameter i (gas 

production, oil production, well count or spud count) 

ci,county is the fraction of parameter i for all combined counties that is assigned to each 

specific county based on 2006 data 

Q2006 is the value of parameter i in 2006 for all other combined counties 

Q2010 is the projected value of parameter i in 2010 for all other combined counties 

Emissions were therefore projected to 2010 for each county in the D-J Basin using the scaling 

factors derived above for each county. Uncontrolled 2010 emissions were estimated according 

to Equation (3): 

Equation (2) j,county,2010 i,county E j,county,2006 E = f ×

where: 

Ej,county,2010 are the projected emissions in a specific county in 2010 for source category j 

Ej,county,2006 are the 2006 baseline emissions in a specific county for source category j 

fi is the scaling factor for each county for parameter i (gas production, oil production, well 

count or spud count) 

The scaling factor based on the appropriate parameter (gas production, oil production, well count 

or spud count) is selected for each source category as described in Table 1. The scaling factors 

for the four parameters used in this analysis for each of the three geographic groupings is 

presented in Table 2 below. 
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Table 2. Scaling factors for the four parameters used in the projection analysis for the three 

geographic groupings. 

Metric Gas Production Oil Production Well Count Spud Count 

Weld 1.216 1.302 1.288 1.413

Yuma 1.721 0.000 1.758 1.000

All other DJ counties 0.732 0.730 0.970 0.452

CONTROLLED 2010 EMISSIONS

This methodology considered any “on-the-books” federal or state regulations that would affect 

the uncontrolled 2010 emissions projections described above. 

Table 3 below lists the “on-the-books” federal and state regulations that affect emissions source 

categories in the oil and gas industry, and the action taken to adjust the 2010 emissions inventory 

appropriately. 

Table 3. Summary of federal and state “on-the-books” regulations affecting the oil and gas 

source categories considered in this inventory. 

Source 

Category Regulation 

Enforcing 

Agency 

Effective 

Date 

Implementation in the 2010 

D-J Basin Emissions 

Projections 

Federal 

Drill Rigs 

Nonroad engine 

Tier standards (1-4) US EPA 

Phase in from 

1996 - 2014 

None – turnover of drill rig 

engines is considered too slow 

to be affected by Tier 

standards. 

Drill Rigs, 

Workover 

Rigs 

Nonroad diesel fuel 

sulfur standards US EPA 

Phase in 

beginning in 

2010 

Assume 50 ppm sulfur in 

nonroad diesel fuel throughout 

D-J Basin. 

All New 

Nonroad 

Engines 

New Source 

Performance Stds. 

(NSPS) US EPA 

Phase in 

beginning 2006 

None – although some new 

compressors will be put into the 

field in the D-J Basin, this 

methodology conservatively 

estimates no application of this 

rule to these engines. 

State 

Natural Gas 

Engines Regulation 7* CDPHE 

Phase in from 

2007 - 2011 

None – see above on 

compressor engines. 

Glycol 

Dehydrators Regulation 7* CDPHE May 2008 

Apply a rule-effectiveness of 

83% to the 90% control 

required for any glycol 

dehydrator emitting more than 

15 tpy VOC. 

Condensate 

Tanks Regulation 7* CDPHE May 2008 

Apply 95% control to any tank 

emitting more than 20 tpy VOC. 

Condensate 

Tanks with 

APENs in 

the EAC Regulation 7* CDPHE May 2007 

Apply a rule-effectiveness of 

83% to the 75% control 

required of total VOC emissions 

in the front range early action 

compact area (EAC) from these 

tanks. 

* Information about the State of Colorado’s Regulation 7 concerning oil and gas emissions sources can be found at 

(http://www.cdphe.state.co.us/ap/oilgas.html) 
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The uncontrolled 2010 emissions were adjusted based on the proposed action described in Table 

3 to account for each regulation that may affect any oil and gas source category considered in 

this inventory. 

The methodology recognizes that there are a number of voluntary and/or required control 

measures that have been partially implemented since 2006, and/or will be implemented 

completely by the calendar year 2010. However, these controls were not incorporated into this 

base case 2010 projection, but rather could form part of the controls to be included in a control 

scenario. 

The resulting controlled 2010 emissions are considered the final 2010 oil and gas emissions 

inventory projection for purposes of the Denver metropolitan area ozone SIP modeling. 

SUMMARY RESULTS

The scaling factors were applied to the baseline 2006 inventory, and “on-the-books” regulations 

were applied to the uncontrolled 2010 emissions projections to generate the final 2010 emissions 

projections and results are presented below. 

Figure 15 shows that compressor engines and drilling rigs combined account for almost 80% of 

NOx emissions in 2010. Similarly, Figure 16 shows that permitted and unpermitted condensate 

tanks and pneumatic devices account for approximately 77% of VOC emissions in 2010. 
G:\IPAMS\Technical_Reports\D-J_Basin\CDPHE_Submission\2010_Proj_Emiss_D-J_Basin_043008.doc 19

0

2,000

4,000

6,000

8,000

10,000

12,000

14,000

16,000

18,000

Adams

Arapahoe

Boulder

Broomfld

Crowley

Denver

Elbert

Fremont

Jefferson

Kit Cars

Larimer

Lincoln

Logan

Morgan

Phillips

Pueblo

Sedgwick

Washngtn

Weld

Yuma

County

2010 NOx Emissions (tons/year)

Other Categories

Glycol Dehydrator

Compressor Engines

Workover rigs

Venting -

recompletions

Pneumatic devices

Permitted Fugitives

Exempt engines

Drill rigs

Figure 13. 2010 NOx emissions by source category and by county in the D-J Basin. 

0

10,000

20,000

30,000

40,000

50,000

60,000

70,000

80,000

Adams

Arapahoe

Boulder

Broomfld

Crowley

Denver

Elbert

Fremont

Jefferson

Kit Cars

Larimer

Lincoln

Logan

Morgan

Phillips

Pueblo

Sedgwick

Washngtn

Weld

Yuma

County

 2010 VOC Emissions (tons/year)

Other Categories

Glycol Dehydrator

Compressor Engines

Workover rigs

Venting - recompletions

Venting - initial completions

Venting - blowdowns

Truck loading of condensate liquid

Small condensate tanks

Pneumatic pumps

Pneumatic devices

Large condensate tanks

Heaters

Permitted Fugitives

Unpermitted Fugitives

Exempt engines

Drill rigs

Figure 14. 2010 VOC emissions by source category and by county in the D-J Basin. 
April 2008 

G:\IPAMS\Technical_Reports\D-J_Basin\CDPHE_Submission\2010_Proj_Emiss_D-J_Basin_043008.doc 20

Drill rigs

26%

Exempt engines

15%

Other Categories

1%

Workover rigs

3%

Heaters

3%

Compressor Engines

52%

Figure 15. 2010 NOx emissions proportional contributions by source category in the DJ Basin. 

Large condensate tanks

45%

Other Categories

1%

Pneumatic devices

17%

Permitted Fugitives

1%

Venting - recompletions

1%

Truck loading of 

condensate liquid

1%

Venting - initial 

completions

1%

Small condensate tanks

14%

Pneumatic pumps

1%

Venting - blowdowns

2%

Unpermitted Fugitives

11%

Drill rigs

0%

Glycol Dehydrator

0%

Compressor Engines

3%

Figure 16. 2010 VOC emissions proportional contributions by source category in the DJ Basin. 
April 2008 

G:\IPAMS\Technical_Reports\D-J_Basin\CDPHE_Submission\2010_Proj_Emiss_D-J_Basin_043008.doc 21

Table 4. 2010 emissions of all criteria pollutants by county for the D-J Basin. 

County 

NOx 

[tons/yr] 

VOC 

[tons/yr] 

CO 

[tons/yr] 

SOx 

[tons/yr] 

PM 

[tons/yr] 

Adams 1,718 2,246 716 9 15

Arapahoe 546 299 187 0 3

Boulder 174 594 135 0 3

Broomfield 13 143 9 0 0

Crowley 46 1 62 0 0

Denver 29 76 13 0 1

Douglas 0 0 0 0 0

Elbert 34 282 22 0 1

El Paso 0 0 0 0 0

Fremont 12 250 7 0 0

Jefferson 4 0 7 0 0

Kit Carson 6 104 3 0 0

Larimer 35 471 22 0 1

Lincoln 10 341 8 0 0

Logan 357 104 133 1 6

Morgan 583 728 541 97 3

Phillips 28 39 18 0 1

Pueblo 0 0 0 0 0

Sedgwick 1 9 0 0 0

Teller 0 0 0 0 0

Washington 212 3,309 156 0 6

Weld 15,768 71,930 10,688 19 555

Yuma 4,832 7,127 2,684 4 176

Totals 24,408 88,989 15,412 131 771

 
April 2008 

G:\IPAMS\Technical_Reports\D-J_Basin\CDPHE_Submission\2010_Proj_Emiss_D-J_Basin_043008.doc Table 5. 2010 NOx emissions [ton/yr] by county and by source category for the D-J Basin. 

County Drill rigs 

Exempt 

engines Heaters 

Workover 

Rigs 

Compressor 

Engines 

Glycol 

Dehydrator 

Other 

Categories 

Adams 11 147 29 29 1,494 0 Arapahoe 5 17 3 3 518 0 Boulder 14 38 8 7 107 0 Broomfield 0 10 2 2 0 0 Crowley 0 0 0 0 46 0 Denver 11 6 1 1 11 0 Douglas 0 0 0 0 0 0 Elbert 2 10 2 2 19 0 El Paso 0 0 0 0 0 0 Fremont 3 6 1 1 0 0 Jefferson 0 0 0 0 4 0 Kit Carson 3 2 0 0 0 0 Larimer 0 22 4 4 4 0 Lincoln 2 2 0 0 6 0 Logan 14 19 4 4 317 0 Morgan 2 11 2 2 468 6 Phillips 5 3 1 1 19 0 Pueblo 0 0 0 0 0 0 Sedgwick 0 1 0 0 0 0 Teller 0 0 0 0 0 0 Washington 36 75 15 15 71 0 Weld 4,255 2,598 514 504 7,734 6 1Yuma 1,906 803 159 156 1,808 0 Totals 6,267 3,769 746 731 12,625 12 2
April 2008 

G:\IPAMS\Technical_Reports\D-J_Basin\CDPHE_Submission\2010_Proj_Emiss_D-J_Basin_043008.doc Table 6. 2010 VOC emissions [ton/yr] by county and by source category for the D-J Basin. 

County 

Drill 

rigs Fugitives 

Large 

condensate 

tanks 

Pneumatic 

devices 

Pneumatic 

pumps 

Small 

condensate 

tanks 

Truck 

loading of 

condensate 

liquid 

Venting - 

blowdowns 

Venting - 

initial 

completions 

Venting - 

recompletions 

Compre

Engin

Adams 1 450 729 595 43 127 17 37 1 1 Arapahoe 0 59 100 68 5 18 2 2 1 1 Boulder 1 102 238 167 11 41 5 13 1 2 Broomfield 0 25 57 42 3 10 1 4 0 0 Crowley 0 0 0 0 0 0 0 0 0 0 Denver 1 15 26 23 2 5 1 1 1 1 Douglas 0 0 0 0 0 0 0 0 0 0 Elbert 0 26 0 40 3 156 2 1 0 0 El Paso 0 0 0 0 0 0 0 0 0 0 Fremont 0 16 0 25 2 204 2 0 0 0 Jefferson 0 0 0 0 0 0 0 0 0 0 Kit Carson 0 5 0 8 1 87 1 2 0 0 Larimer 0 59 153 90 7 154 5 1 0 0 Lincoln 0 5 0 8 1 318 3 0 0 0 Logan 1 49 0 74 5 847 9 1 1 2 Morgan 0 32 0 44 3 376 4 2 0 0 Phillips 0 8 0 13 1 0 0 3 1 1 Pueblo 0 0 0 0 0 0 0 0 0 0 Sedgwick 0 1 0 2 0 5 0 0 0 0 Teller 0 0 0 0 0 0 0 0 0 0 Washington 3 200 0 303 22 2,690 27 12 4 5 Weld 295 7,317 38,985 10,513 761 7,784 902 1,654 413 556 2Yuma 132 2,128 0 3,225 235 0 0 475 185 249 Totals 434 10,498 40,288 15,238 1,104 12,821 980 2,208 608 819 2