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U.S. ENVIRONMENTAL PROTECTION AGENCY
OFFICE OF INSPECTOR GENERAL
EPA Needs to Improve
Air Emissions Data for the
Oil and Natural Gas
Production Sector
Report No, 13-P-0161
February 20, 2013
Scan this mobile
code to learn more
about the EPA OIG.
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Report Contributors:
Rick Beusse
Chris Dunlap
Kevin Good
Erica Hauck
Renee McGhee-Lenart
Julie Narimatsu
Abbreviations
AERR
Air Emissions Reporting Requirements
CAA
Clean Air Act
CFR
Code of Federal Regulations
EIA
U.S. Department of Energy's Energy Information Administration
EPA
U.S. Environmental Protection Agency
ERT
Electronic reporting tool
FTE
Full-time equivalent
FY
Fiscal year
GAO
U.S. Government Accountability Office
GHG
Greenhouse gas
HAP
Hazardous Air Pollutants
NAAQS
National Ambient Air Quality Standards
NATA
National Air Toxics Assessment
NEI
National Emissions Inventory
NESHAP
National Emissions Standards for Hazardous Air Pollutants
NOx
Nitrogen oxides
NSPS
New Source Performance Standards
OAP
Office of Atmospheric Programs
OAQPS
Office of Air Quality Planning and Standards
OAR
Office of Air and Radiation
OIG
Office of Inspector General
ORD
Office of Research and Development
pm2,
Fine particulate matter
PMio
Inhalable coarse particulate matter
SIP
State implementation plan
VOC
Volatile organic compounds
WebFIRE
Web Factor and Information Retrieval System
Cover photo: A natural gas production facility next to a playground and housing
development. (EPA photo)
Hotline
To report fraud, waste, or abuse, contact us through one of the following methods:
e-mail: OIG Hotline@epa.gov write: EPA Inspector General Hotline
phone: 1-888-546-8740 1200 Pennsylvania Avenue, NW
fax: 202-566-2599 Mailcode 2431T
online:
http://www.epa.gov/oiq/hotline.htm
Washington, DC 20460
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U.S. Environmental Protection Agency 13-P-0161
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At a Glance
Why We Did This Review
We initiated this review to
determine whether the U.S.
Environmental Protection
Agency (EPA) has the data
needed to make key decisions
regarding air emissions from
oil and natural gas production.
Key decisions include the
need for regulations,
enforcement and permitting
decisions, and risk
assessment, among others.
Gas production in the United
States has grown significantly
in recent years. Between 1992
and 2010, about 210,000 new
gas wells were drilled. The
U.S. Department of Energy
projects that onshore crude oil
and natural gas production will
increase 30 and 18 percent,
respectively, from 2009 to
2025. The oil and gas
production sector and its
various production processes
emit large amounts of harmful
pollutants that impact air
quality on local, regional, and
global levels.
This report addresses the
following EPA Goal or
Cross-Cutting Strategy:
Taking action on climate
change and improving air
quality.
For further information,
contact our Office of
Congressional and Public
Affairs at (202) 566-2391.
The full report is at:
www.epa.qov/oiq/reports/2013/
20130220-13-P-0161.pdf
EPA Needs to Improve Air Emissions Data for
the Oil and Natural Gas Production Sector
What We Found
High levels of growth in the oil and natural gas (gas) production sector, coupled with
harmful pollutants emitted, have underscored the need for EPA to gain a better
understanding of emissions and potential risks from the production of oil and gas.
However, EPA has limited directly-measured air emissions data for air toxics and
criteria pollutants for several important oil and gas production processes and
sources, including well completions and evaporative ponds. Also, EPA does not
have a comprehensive strategy for improving air emissions data for the oil and gas
production sector; the Agency did not anticipate the tremendous growth of the
sector, and previously only allocated limited resources to the issue.
In addition to their use in making a variety of key decisions, EPA uses air emissions
data to develop emission factors. These are representative values that relate the
quantity of a pollutant released with an activity associated with its release. States
use EPA's emission factors to develop emission inventories, issue permits for
facilities, and take enforcement actions. Limitations in EPA's air emissions data for a
number of oil and gas production pollutants have contributed to emission factors of
questionable quality. About half of EPA's Web Factor and Information Retrieval
System oil and gas production emission factors are rated below average or unrated
because they are based on insufficient or low quality data.
EPA uses its National Emissions Inventory (NEI) to assess risks, track trends, and
analyze envisioned regulatory controls. However, oil and gas production emissions
data in the 2008 NEI are incomplete for a number of key air pollutants. For example,
only nine states submitted criteria pollutant emissions data for small stationary
sources. Because so few states submitted data for this sector, we believe the NEI
likely underestimates oil and gas emissions. This hampers EPA's ability to
accurately assess risks and air quality impacts from oil and gas production activities.
Recommendations and Planned Agency Corrective Actions
We recommend that EPA develop and implement a comprehensive strategy for
improving air emissions data for the oil and gas production sector, prioritize which oil
and gas production emission factors need to be improved, develop additional
emission factors as appropriate, and ensure the NEI data for this industry sector are
complete. EPA concurred with our recommendations to develop a comprehensive
strategy, improve and prioritize emission factors, and develop default nonpoint
emission estimates. The Agency did not concur with our recommendations to ensure
that states submit required data and develop default calculation guidance. These
recommendations are unresolved pending the Agency's final report response.
Noteworthy Achievements
EPA is conducting field studies to develop new methods to measure emissions and
investing in a new Emissions Inventory System.
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UNITED STATES ENVIRONMENTAL PROTECTION AGENCY
WASHINGTON, D.C. 20460
THE INSPECTOR GENERAL
February 20, 2013
MEMORANDUM
SUBJECT: EPA Needs to Improve Air Emissions Data for the Oil and
Natural Gas Production Sector
Report No. 13-P-0161
FROM: Arthur A. Elkins, Jr.
TO: Gina McCarthy
Assistant Administrator for Air and Radiation
Lek Kadeli
Acting Assistant Administrator for Research and Development
This is our report on the subject evaluation conducted by the Office of Inspector General (OIG)
of the U.S. Environmental Protection Agency (EPA). This report contains findings that describe
the problems the OIG has identified and corrective actions the OIG recommends. The Agency
disagreed with two of our recommendations, which are unresolved pending the Agency's final
report response. This report represents the opinion of the OIG and does not necessarily represent
the final EPA position. Final determinations on matters in this report will be made by EPA
managers in accordance with established audit resolution procedures.
Action Required
In accordance with EPA Manual 2750, you are required to provide a written response to this
report within 60 calendar days. You should include a corrective actions plan for agreed-upon
actions, including milestone dates. Your response will be posted on the OIG's public website,
along with our memorandum commenting on your response. Your response should be provided
as an Adobe PDF file that complies with the accessibility requirements of Section 508 of the
Rehabilitation Act of 1973, as amended. The final response should not contain data that you do
not want to be released to the public; if your response contains such data, you should identify the
data for redaction or removal. Please e-mail your response to Carolyn Copper, Assistant
Inspector General for Program Evaluation, at copper.carolyn@epa.gov. We have no objections to
the further release of this report to the public. We will post this report to our website at
http://www.epa.gov/oig.
# JL \
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If you or your staff have any questions regarding this report, please contact Carolyn Copper at
(202) 566-0829 or copper.carolvn@epa.gov; or Rick Beusse, Director for Air and Research
Evaluations, at (919) 541-5747 or beusse.rick@epa.gov.
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EPA Needs to Improve Air Emissions Data
for the Oil and Natural Gas Production Sector
13-P-0161
Table of C
Chapters
1 Introduction 1
Purpose 1
Background 1
Noteworthy Achievements 7
Scope and Methodology 8
2 Limited Air Emissions Data for Oil and Gas Production
Hampers EPA's Ability to Assess Airborne Risks 10
EPA Has Limited Air Emissions Data for Several Key Oil and
Gas Production Processes and Sources 10
EPA Lacks Data to Develop and Improve Emission Factors
Impacting Key Decisions for Many Oil and Gas Processes 12
Oil and Gas Production Emissions Data in EPA's NEI Are Incomplete 16
Limited Data Could Affect Decision-Making Impacting Human Health
and the Environment 20
Conclusions 20
Recommendations 21
Agency Comments and OIG Evaluation 22
Status of Recommendations and Potential Monetary Benefits 23
Appendices
A Agency Comments on Draft Report 24
B OIG Evaluation of Agency Comments 28
C Growth in Oil and Gas Production Industry 30
D Final Revised 2012 NSPS and NESHAP Rules 32
E Descriptions of Equipment and Processes for Oil and Gas Production 34
F Distribution 36
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Chapter 1
Introduction
Purpose
We conducted this evaluation to determine whether the U.S. Environmental
Protection Agency (EPA) has the data needed to make key decisions regarding
air emissions from oil and natural gas (gas) production activities. These decisions
include establishing regulations, determining applicability of sources to
regulations, permitting facilities, evaluating the adequacy and cost-effectiveness
of regulatory controls, assessing residual risks from facilities,1 evaluating State
Implementation Plans (SIPs),2 and taking enforcement actions.
Background
Industry Growth
Gas production in the United States has grown significantly in recent years. From
1992 to 2010,3 the number of producing gas wells increased by 76 percent.
Onshore gross withdrawals of gas increased by about 43 percent. About 11,000
new wells were drilled annually from 1992 to 2010, on average. According to a
2011 EPA fact sheet,4 the United States had nearly 1.1 million producing oil and
gas wells in 2009. Growth in gas production has been particularly significant in
areas covered by EPA Regions 3, 6, and 8. For example, in Region 8, the number
of gas wells increased by 416 percent and gross withdrawals increased by 163
percent between 1992 and 2010.
Unlike gas production, onshore production of crude oil decreased from
2.28 billion barrels in 1992 to 1.4 billion barrels in 2010, but is expected to
increase in future years. The U.S. Department of Energy's Energy Information
Administration (EIA)5 projects that both onshore crude oil and gas production
will increase by 30 percent and 18 percent, respectively, between 2009 and 2025.
In addition, the EIA projects that about 39,000 new gas wells will be drilled per
1 Comprehensive risk assessments involve a number of activities and types of information beyond emissions data,
including dispersion modeling, human exposure assessments, and dose-response relationships. We focused only on
oil and gas production emissions data. We did not evaluate the limitations or uncertainties associated with the other
types of information used in comprehensive risk assessments.
2 A SIP is a state's blueprint for how it will attain and/or maintain the National Ambient Air Quality Standards. It
contains the state's proposed control measures and strategies, subject to EPA review and approval.
3 2010 was the most recent year for which data were available at the time we conducted our analysis.
4 EPA Fact Sheet, Proposed Amendments to Air Regulations for the Oil and Natural Gas Industry, July 2011.
5 EIA collects, analyzes, and disseminates independent and impartial energy information to promote sound
policymaking, efficient markets, and public understanding of energy and its interaction with the economy and the
enviromnent. By law, EIA's data, analyses, and forecasts are independent of approval by any other officer or
employee of the U.S. Government. Source: http://www.eia.gov/about/mission overview.cfm.
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year during the same period. Appendix C provides more details on the growth in
oil and gas production.
Oil and Gas Processes and Sources of Airborne Emissions
The oil and natural gas sector includes operations involved in the extraction and
production of oil and natural gas, as well as the processing, transmission, and
distribution of natural gas. Specifically for oil, the sector includes all operations
from the well to the point of custody transfer at a petroleum refinery. For natural
gas, the sector includes all operations from the well to the customer.
Our evaluation focused on activities associated with onshore oil and gas
production. Production involves the extraction of oil and gas from underground
formations and the initial separation of crude oil and gas from other components
in the hydrocarbon stream coming from the ground. These activities are
commonly referred to as upstream activities.
As shown in table 1, the sources of airborne emissions from oil and gas
production (upstream) activities can be broken down into three major categories.
Table 1: Source categories of airborne emissions from upstream activities
Category
Type of emissions
Sources of emissions
Combustion
sources
Nitrogen oxides (NOx)a,c and carbon
monoxide resulting from the burning
of hydrocarbon (fossil) fuels.
Air toxics, particulate matter (PM),
uncombusted volatile organic
compounds, and methane are also
emitted.
Engines, heaters, flares, incinerators, and
turbines.
Vented
sources
Volatile organic compounds
(VOCs)a,b, air toxics, and methane
resulting from direct releases to the
atmosphere.
Pneumatic devices, dehydration processes,
gas sweetening processes, chemical
injection pumps, compressors, tanks, and
well testing, completions, and workovers.
Fugitive
sources
VOCsa,c, air toxics, and methane
resulting from uncontrolled and
under-controlled emissions.
Equipment leaks through valves,
connectors, flanges, compressor seals, and
related equipment and evaporative sources
including wastewater treatment, pits, and
impoundments.
Source: Office of Inspector General (OIG)-developed table from the American Petroleum Institute's
Compendium of Greenhouse Gas Emissions Estimation Methodologies for the Oil and Gas Industry, 2009
and selected other sources.
aFine particulate matter (PM2.5) emissions can be created by secondary formation due to chemical reaction
in the atmosphere from precursor emissions such as NOx and VOCs.
bOzone emissions can be created by secondary formation due to photochemical reactions in the
atmosphere from precursor emissions such as NOx and VOCs. Winter ozone exceedances in western
states have been linked to oil and gas drilling.
Pollutants Emitted and Associated Health Risks
Oil and gas production processes and sources emit large amounts of harmful
pollutants that can impact air quality globally, regionally, and locally. Table 2
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describes the health impacts of some significant pollutants emitted from the oil
and gas production sector.
Table 2: Health impacts of significant pollutants emitted from upstream oil and gas production
activities
Pollutant(s)
Health impacts
Greenhouse
gases (methane/
carbon dioxide)
Potential health impacts related to climate change will vary, but threats include increased
incidence of serious infectious disease, extreme temperatures that lead directly to loss of
life, and warmer temperatures that can increase air and water pollution and result in
human health impacts.
NOx and VOCs,
which contribute
to ground-level
ozone
Health impacts may include reduction of lung function, inflammation of airways,
aggravation of asthma, increased susceptibility to respiratory illnesses (e.g., pneumonia
and bronchitis) and premature death. Vulnerable populations (e.g., people with lung
disease, children, and the elderly) are especially at risk.
Fine particulate
matter (PM 2.5)
Health impacts may include worsening of lung function, asthma attacks, bronchitis,
increased susceptibility to respiratory infections, and premature death.
Air toxics
including
benzene,
toluene,
ethylbenzene,
and xylenes
Health impacts from short-term exposure may include skin and sensory irritation, central
nervous system problems, and respiratory problems. Health impacts from long-term
exposure may include problems with kidney, liver, and blood systems. For example,
benzene is a human carcinogen and health impacts from short-term exposure may
include drowsiness, dizziness, headaches, and irritation of the eyes, skin, and respiratory
tract. Long-term exposure has been linked to various blood disorders, reproductive
effects, and increased incidence of leukemia.
Source: OIG-developed table.
Methods for Quantifying Emissions
Quantifying air emissions is important to achieving effective control and
oversight of sources of air emissions. Several methods exist for quantifying
emissions, including direct measurement of sources and estimation techniques
such as emission factors and engineering calculations:
Direct measurement involves measuring actual emissions and collecting
empirical or directly-measured data from a source or process.
Emission factors are representative values that relate the quantity of a
pollutant released to the atmosphere with an activity associated with the
release of that pollutant. EPA and states use emission factors to produce
emission estimates for specific sources or processes at a facility.
Engineering calculations refer to the estimation of emissions using
engineering parameters.
EPA's Emissions Inventories
Emissions inventories identify, by source, the air pollutant emissions in a specific
geographic area for a specific time interval. EPA and states use emissions
inventories to evaluate air pollution problems and assess the effectiveness of air
pollution policy. Inventories represent an estimate of total emissions and are
based to a large extent on data derived from emission factors. EPA has two
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primary emissions inventories that reflect emissions from oil and gas production:
the National Emissions Inventory (NEI) and the Inventory of U.S. Greenhouse
Gas (GHG) Emissions and Sinks (known as the GHG Inventory):
EPA's NEI is a nationwide inventory containing detailed estimates of both
criteria6 and toxic air emissions from all sources of air emissions. The NEI
is based primarily on emissions data submitted by state, local, and tribal
air pollution control agencies. The NEI is compiled every 3 years, with the
most recent inventory representing emissions in 2008. EPA uses the NEI
for a variety of purposes, including developing regulations, modeling
efforts to support rulemakings, characterizing risks from air toxic
emissions, and assessing emission trends over time. The environmental
staff from one state said that they use the NEI for modeling efforts to
support their SIP proposal process.7
For GHGs, EPA annually prepares the national GHG Inventory Report,
which provides estimates of the amount of domestic GHGs emitted into
and removed from the atmosphere. Primarily, the GHG Inventory Report
fulfills the United States' commitment to the United Nations Framework
Convention on Climate Change (1992), which requires parties to develop
national inventories of anthropogenic GHG emissions and GHG removals.
Figure 1 explains how emissions data, emission factors, and emissions inventories
for air toxics and criteria pollutants are related and used to make key decisions.
6 The Clean Air Act requires EPA to set National Ambient Air Quality Standards for six common air pollutants.
These commonly found air pollutants (also known as "criteria pollutants") are ozone, particulate matter, carbon
monoxide, nitrogen oxides, sulfur dioxide, and lead.
7 States may use NEI data to develop their SIP proposals; however, SIP proposals must undergo public review and
comment before they are approved.
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Figure 1: Types of criteria and air toxics emissions data used to make decisions
EPA's NEI is intended to include air emissions from all states and from all sources (large and small stationary
sources, and mobile sources). It represents an estimate of all air emissions of criteria and toxic air pollutants in
the United States. Although the NEI contains some directly-measured emissions, such as those measured by
continuous emission monitors at large stationary sources, the NEI data for oil and gas production is based largely
on estimates calculated from emission factors.
Uses/Decisions: EPA uses the NEI for air quality modeling conducted in support of regulations; assessing risks to
the public; measuring air emission trends overtime; informing development ofSIPs; and developing residual risk
and air toxics rules. EPA uses this information to make key decisions on risks and air quality impacts.
NEI
These data are obtained through the measurement of actual emissions coming from a source or process, and
can be thought of as "empirical" data. These emissions data are measured using standardized measurement
methods that quantify emissions from a source. This includes using established test methods, but also includes
data collected using newer direct and remote emission measurement techniques.
Uses/Decisions: This type of data is used to develop emission factors, as well as to improve existing emission
factors. Measured and source-specific data can also be submitted directly to NEI in addition to being used for
emission factors. If this type of data exists for a given source or process, it can be used to make permitting and
enforcement decisions and to conduct analyses for development of regulations.
Measured and source-specific emissions data
An emission factor is a tool used to estimate air pollutant emissions from a normally operating process or activity.
An emission factor relates the quantity of pollutants released to the atmosphere from a process to a specific
activity associated with generating those emissions. For most application purposes, users typically assume that
an emission factor represents the long-term average emissions for all facilities in a particular source category.
EPA's emission factors are compiled in AP-42a and the Web Factor Information Retrieval System (WebFIRE).b
Uses/Decisions: Emission factors are used to estimate average emissions across a large number of sources,
such as in the development of an emissions inventory. Emission factors are also frequently used to make
applicability determinations, and permitting and enforcement decisions. Emission factors may also be used to
conduct analyses for development of regulations.
Emission factors
Source: OIG-developed figure.
aAP-42, Compilation of Air Pollutant Emission Factors, is EPA's primary compilation of emission factor information. It
contains emission factors and process information for more than 200 air pollution source categories.
bWebFIRE is EPA's online repository of recommended emission factors.
Complexity of Oil and Gas Emissions
The complexity of oil and gas emissions presents a challenge to estimating air
emissions as well as overseeing the industry. Examples of this complexity include:
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Different geological formations can produce different types of fluids and
gases with different air emissions. For example, coal bed methane wells
produce less VOCs than conventional gas wells. VOC and hazardous air
pollutants (HAP) content of gas and condensate can also vary from
location to location, according to EPA.
Emissions can differ among wells in the same formation and in the same
field. Well production and pressure decline over time. Flow rates of wells
next to each other can vary at different times.
The level of emissions may also vary by season and temperature. For
example, colder conditions require heaters, which produce additional
emissions.
Well pressure also impacts the effectiveness of control options. If there is
not enough pressure to push the emissions out of the ground, efforts to
capture the emissions might be technically infeasible.
Clean Air Act Regulations That Affect Oil and Gas Production
A number of Clean Air Act (CAA) regulations affect the oil and gas industry.
These include EPA's newly revised New Source Performance Standards (NSPS)
and National Emission Standards for Hazardous Air Pollutants (NESHAP) rules
for the oil and gas sector issued in April 2012.8 The previous NSPS and NESHAP
rules focused primarily on larger oil and gas facilities, such as gas processing
plants. The revised rules will regulate emissions from several upstream sources
and processes not covered by the previous rules, most notably well completions.
For well completions, the rules will address new wells that are hydraulically
fractured and existing wells as they are refractured. See appendix D for more
details on the final revised 2012 NSPS and NESHAP rules. Other existing rules
that affect engines used in oil and gas production include the NSPS rule for
Stationary Spark Ignition Internal Combustion Engines and the NESHAP rule for
Reciprocating Internal Combustion Engines.
With respect to GHGs, EPA issued the Mandatory Reporting of Greenhouse
Gases rule9 ("GHG Reporting Rule") in October 2009 that requires facilities to
report their GHG emissions annually to EPA if they meet a certain emission
threshold. Subpart W of the GHG Reporting Rule, issued in November 2010,
requires oil and natural gas facilities to track and report equipment leaks and
vented emissions for calendar year 2011 and submit that information in
September 2012. Starting in 2013, reports must be submitted to EPA by March 31
of each year. Subpart W also provides methodologies for calculating emissions
from each source type.
840 CFR Parts 60 and 63.
940 CFR Part 98.
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EPA's Budget and Resources for Oil and Gas Production Activities
EPA's Office of Air and Radiation (OAR)specifically, the Office of Air Quality
Planning and Standards (OAQPS) and Office of Atmospheric Programs (OAP)
and the Office of Research and Development (ORD) are responsible for collecting
emissions data and developing methods to measure and/or estimate emissions.
EPA does not maintain precise budget data on its expenditures by industry sector.
However, Agency officials were able to estimate the resources devoted to oil and
gas production activities in most instances. From fiscal year (FY) 2008 to FY 2011,
ORD allocated about $455,000 in extramural funds and about 0.5 full-time
equivalents (FTEs) per year to oil and gas production-related research. In that same
period, OAQPS allocated an estimated $2.7 million to oil and gas production
activities. From FYs 2010 to 2011, OAQPS had about 5 FTEs per year devoted to
oil and gas activities such as rulemaking development. OAP staff were not able to
break out specific budget figures and FTEs used directly to address oil and gas
production emissions, although they did provide higher level budget information
for the broader programs that include oil and gas production activities.
Noteworthy Achievements
ORD and OAR Collaborative Research: ORD and OAQPS as well as their
EPA regional and state partners conducted field studies to develop new methods
to measure fugitive and other emissions from well production pads and
evaporative ponds. These studies focused on remote emission assessment
techniques that allow for offsite data collection.
Emissions Inventory System: EPA has invested in the new Emissions Inventory
System to improve the data collection process and enhance the quality of the NEI.
According to OAQPS staff, the system allowed EPA to compile the NEI using
fewer resources for the actual collection of data. Therefore, more resources were
allocated to ensuring data quality. The Emissions Inventory System helps to
ensure consistency by comparing state-reported emissions data to emissions data
in the system, as well as comparing state data year to year.
Emission Factors: In response to the OIG's 2006 report10, EPA has developed
the Electronic Reporting Tool (ERT), incorporated electronic reporting
requirements into a number of rulemakings, and created an electronic data portal
for sources to submit data electronically directly to EPA. EPA has also issued a
draft report on "Recommended Procedures for Development of Emissions Factors
and Use of the WebFIRE Emissions Factor Database" (December 17, 2010).
Natural Gas STAR: Initiated in 1993, EPA's Natural Gas STAR program is a
voluntary program that partners with oil and gas companies to reduce methane
10EPA OIG Report No. 06-P-00017, EPA Can Improve Emissions Factors Development and Management, March
22, 2006.
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emissions through the development of technologies and best practices. The
program offers its partners guidance and technical assistance. According to EPA,
the program currently has 130 partners and has eliminated a total of 994 billion
cubic feet of methane since its inception. In 2010, EPA reported that 73.1 billion
cubic feet of methane reductions came from oil and gas production sector partners
(78 percent of total methane emission reductions).
Greenhouse Gas Reporting Program: EPA issued the GHG Reporting Rule on
October 30, 2009. It requires the annual reporting of greenhouse gas emissions.
EPA issued the rule requiring the reporting of GHG emissions from the petroleum
and natural gas industry (Subpart W) on November 30, 2010. According to EPA,
these data will improve EPA's understanding of the location and magnitude of
GHG emissions from oil and gas systems across the United States.
Scope and Methodology
To assess whether EPA has the data needed to make key decisions regarding air
emissions from oil and gas production activities, we obtained and reviewed
applicable EPA, Office of Management and Budget, and other federal policies,
procedures, and guidance documents. We obtained and reviewed EPA, state, and
local studies pertaining to oil and gas emissions and associated risks, and
interviewed managers and staff from OAQPS, ORD, OAP, the Office of
Enforcement and Compliance Assurance, and EPA Regions 3, 6, and 8. We
discussed and obtained corroborating data and documents about air emissions
from the oil and gas production sector, including legislative and regulatory
developments, recent and ongoing research, emission factors, emissions
inventories, measurement methods and techniques, quality assurance processes,
budget and resource issues, and permitting, compliance, and enforcement (at both
the state and federal levels). We interviewed managers and staff from four states
that have experienced recent growth in oil and/or gas production:
Wyoming Department of Environmental Quality
Texas Commission on Environmental Quality
Pennsylvania Department of Environmental Protection
Colorado Department of Public Health and Environment
We also interviewed representatives from the Western Regional Air Partnership
and Natural Resources Defense Council due to their expertise on oil and gas
production issues.
We reviewed EPA's oil and gas production sector emission factors, as compiled
in AP-42 and Web Factor and Information Retrieval System (WebFIRE). In
addition, we analyzed oil and gas production emissions data from the 2008 NEI
(Version 1.5), provided by OAQPS staff.
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We conducted our work from March 2011 to September 2012 in accordance with
generally accepted government auditing standards. Those standards require that
we plan and perform our review to obtain sufficient, appropriate evidence to
provide a reasonable basis for our findings and conclusions based on our
objectives. We believe that the evidence obtained provides a reasonable basis for
our findings and conclusions based on our objectives.
Prior Reports
Prior reports by EPA OIG and the U.S. Government Accountability Office (GAO)
applicable to this evaluation included:
GAO Report No. 11-34: Federal Oil and Gas Leases: Opportunities Exist
to Capture Vented and Flared Natural Gas, Which Would Increase
Royalty Payments and Reduce Greenhouse Gases, October 29, 2010
GAO Report No. 09-872: Energy Policy Act of2005: Greater Clarity
Needed to Address Concerns with Categorical Exclusions for Oil and Gas
Development under Section 390 of the Act, September 16, 2009
EPA OIG Report No. 08-P-0206, Voluntary Greenhouse Gas Reduction
Programs Have Limited Potential, July 23, 2008
EPA OIG Report No. 08-P-0020, Improvements in Air Toxics Emissions
Data Needed to Conduct Residual Risk Assessments, October 31, 2007
EPA OIG Report No. 07-B-00002, Assessment of EPA's Projected
Pollutant Reductions Resulting from Enforcement Actions and Settlements,
July 24, 2007
EPA OIG Report No. 06-P-00017, EPA Can Improve Emissions Factors
Development and Management, March 22, 2006
EPA OIG Report No. 04-P-00021, EPA Needs to Improve Tracking of
National Petroleum Refinery Compliance Program Progress and Impacts,
June 22, 2004
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Chapter 2
Limited Air Emissions Data for Oil and Gas Production
Hampers EPA's Ability to Assess Airborne Risks
EPA has limited directly measured air emissions data on criteria and air toxic
pollutants for several important oil and gas production processes and sources. This
type of data is used to develop emission factors, which EPA and states rely on to
estimate air emissions. However, about half of EPA's WebFIRE emission factors
for oil and gas production are rated poor, below average, or are unrated. EPA has
also developed a nationwide inventory of air emissions, NEI, from large and small
stationary sources, and mobile sources for criteria and some air toxic pollutants, but
the data in the NEI are also incomplete. EPA acknowledges that better data for
several key processes are needed. However, we found that EPA does not have a
comprehensive strategy for improving air emissions data for the oil and gas
production sector. The Agency has not addressed these issues because it did not
anticipate the tremendous growth of the sector and had allocated limited resources
to it. Limited data from direct measurements, poor quality emission factors, and
incomplete NEI data hamper EPA's ability to assess air quality impacts from oil
and gas production activities. With limited data, human health risks are uncertain,
states may design incorrect or ineffective emission control strategies, and EPA's
decisions about regulating industry may be misinformed.
EPA Has Limited Air Emissions Data for Several Key Oil and Gas
Production Processes and Sources
EPA has limited directly measured air emissions data for criteria and air toxic
pollutants for several key oil and gas production processes and sources. For
example, OAQPS lacked data on well completions and evaporative ponds in
conducting analyses for the proposed revised 2011 NSPS and NESHAP rules.11
Due to the lack of directly measured VOC data, OAQPS staff used GHG
inventory estimates of methane emissions to derive estimates of VOC emissions
coming from well completions. In addition, EPA stated in the proposed rules that
it could not regulate evaporative ponds (fugitive emissions) due to a lack of
emissions data. The Agency solicited comments on methods for calculating such
emissions. Appendix E provides descriptions of key oil and gas production
sources and processes.
EPA Lacks Direct Measurement Methods But Studies Are Being
Conducted
EPA has not developed methods for directly measuring criteria and air toxic
pollutant emissions from certain oil and gas production sources and processes
nEPA issued final regulations in 2012. See 40 CFR Parts 60 and 63.
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such as well completions. However, the Agency has developed methods for
measuring methane, one of the GHGs, from oil and gas sources. ORD staff stated
that direct measurement methods are the most accurate measurement techniques.
The disadvantages of onsite direct measurement techniques include the need for
access to the well production site, the expense of testing, and the potential risk of
injury (e.g., needing to climb to the top of a tank to measure emissions).
Nonetheless, according to ORD staff, they are in the process of developing direct
measurement methods for measuring air emissions from oil and gas production
sources for criteria and air toxic pollutants.
Due to the disadvantages of onsite direct measurement methods for some sources,
EPA has conducted and continues to conduct studies to develop remote sensing
and mobile monitoring methods. These methods do not require onsite
measurement. ORD staff said that these methods are likely the only way to
directly measure emissions from well completions. They may also be useful for
measuring fugitive emissions from evaporative ponds. ORD recently developed a
measurement method to measure emissions from well production pads. ORD staff
plan to submit the remote measurement method to EPA's Emission Measurement
Center in OAQPS for possible inclusion in its list of approved test methods. ORD
has also initiated a study of condensate and produced water tanks, and is
considering a study in collaboration with EPA Region 3 to understand the impacts
of oil and gas emissions in the Marcellus Shale region. While progress continues,
more research is needed to develop additional methods for several oil and gas
production processes.
EPA Has Allocated Limited Resources to Oil and Gas Production
Research and Studies
According to ORD staff, EPA did not previously place a priority on oil and gas
production research, but EPA's priority for oil and gas research is rising. Over the
last 4 fiscal years, ORD's National Risk Management Research Lab12 and OAR's
OAQPS have averaged less than one full FTE per year to oil and gas production-
related studies. From FY 2008 to 2011, ORD allocated about $455,000 total in
extramural funds to oil and gas production-related research. OAQPS allocated
about $540,000 for measurements and methods development. ORD has relied on
research funding from Regional Applied Research Effort grants and funding from
other offices, such as OAQPS.
EPA Lacks a Coordinated, Cross-Office Strategy for Improving the
Collection of Data
EPA does not have a coordinated, cross-office strategy or national approach to
improve the collection of air emissions data for oil and gas production. According
to OAP staff, OAR has a GHG data collection strategy in the GHG Reporting
12 This laboratory is ORD's laboratory for risk management research. Its mission is to advance scientific and
engineering solutions to manage current and future environmental risk.
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Rule (Subpart W).13 While Subpart W requires oil and gas production facilities to
report GHG data by September 2012, in our view, this is one part of an effort to
address GHGs from this industry sector. It is not a coordinated, cross-office
strategy for improving the collection of all types of air emissions data for oil and
gas production sources commensurate with recent and projected growth in this
industry sector.
According to an ORD manager, ORD has made a concerted effort to identify the
highest priorities for inventory data development. ORD's Air, Climate, and
Energy Research Action Plan includes multiple projects that support the research
needs of EPA offices, including those involved with the oil and gas sector. The
plan provides information about the need for collaboration with partners.
According to EPA, the research plan was developed with considerable input from
Agency offices that address oil and gas production issues, but it was developed to
guide only ORD's efforts. Further, the plan does not specifically address oil and
gas data limitations. While a step in the right direction, the plan is not a cross-
office strategy or national approach to improving the collection of air emissions
data for oil and gas production sources.
In April 2012, EPA and the Departments of Energy and the Interior signed a
Memorandum of Agreement to form a multi-agency working group. It will
address the high priority research questions associated with the development of
unconventional shale gas and tight oil resources. One component of this effort is
developing a cross-agency, formal, multi-year research plan that will, among
other things, identify gaps in available data and appropriate activities to address
them.
EPA Lacks Data to Develop and Improve Emission Factors Impacting
Key Decisions for Many Oil and Gas Processes
Historically, EPA has not received directly measured data, also called source
testing data, from state and local agencies to develop and improve its emission
factors because states and local agencies were not required to provide the data to
EPA. For that reason, EPA has focused on developing the Electronic Reporting
Tool (ERT), which provides an electronic format for facilities to send their direct
measurement results directly to EPA. OAQPS staff stated that their focus has
been on development of the ERT tool and not independently developing new or
improving existing emission factors.
EPA needs to develop new WebFIRE emission factors for certain key oil and gas
production processes/sources and pollutants that lack them. Many of EPA's
existing oil and gas production emission factors are of questionable quality
because they are based on limited and/or low quality data. Even so, states and
facilities use EPA emission factors to develop emissions inventories and make
13 40 CFR งง 98.230 to 98.238.
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key permitting and enforcement decisions. Emission factors are used because they
are the least expensive method for estimating emissions. Developing new
emission factors and improving existing ones would help ensure that EPA regions
and the states have accurate emission estimates to complete these tasks.
EPA Has Not Developed New Emission Factors
Due to lack of state data and EPA's focus on ERT, the Agency has not developed
new WebFIRE emission factors for certain oil and gas production processes and
sources. For example, we did not identify any emission factors for evaporative
ponds. According to a 2009 Department of Energy report, in semiarid regions,
hot, dry air moving from a land surface will result in high evaporation rates for
small evaporation ponds. We also did not identify emission factors for criteria and
air toxic pollutants for produced water tanks, well completions, or pneumatic
devices. Table 3 lists the key oil and gas production processes and sources that
have and do not have EPA emission factors/models to estimate emissions.
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Table 3: Key emission sources with EPA emission factors or models (or EPA-approved models)
Emission
sources
Nitrogen
oxides
voc
Carbon
monoxide
Fine
particulate
matter
(PM2.5) and
inhalable
coarse
particulate
matter (PM10)
Sulfur
oxides
Air toxics
GHGsa
Internal
combustion
engines
Yes
Yes
Yes
Yes
Yes
Yesb
Yes
Process
heaters
Yes
Yes
Yes
PM10 - Yes
PM2.5 No
Yes
Yesb
Yes
Flares and
enclosed
combustors
No
Yes
No
No
No
No
No
Dehydrators
No
Yes-Model
GRI-
GLYCalc
No
No
No
Yes-Model
GRI-GLYCalc
Tanks
(condensate,
storage, oil,
etc.)
Not
applicable
Yes-Models
E&PTANK
GRI-
HAPCalc
EPA's TANK
Not
applicable
Not
applicable
Not
applicable
Yes-
Models
E&P TANK
GRI-
HAPCalc
EPA's
TANK
Yes-
Model
E&P
TANK
Amine
treaters
No
Yes- Model
AMINECalc
No
No
Yes
Yes-Model
AMINECalc
Evaporative
ponds
Not
applicable
No
Not
applicable
Not
applicable
Not
applicable
No
No
Produced
water tanks
Not
applicable
Noc
Not
applicable
Not
applicable
Not
applicable
Noc
Yes
Well
completions
Not
applicable
Noc
Not
applicable
Not
applicable
Not
applicable
Noc
Yes
Pneumatic
devices
Not
applicable
Noc
Not
applicable
Not
applicable
Not
applicable
Noc
Yes
Source: OIG-developed table from AP-42, WebFIRE, and interviews with OAR staff.
a Emission factor exists for methane, carbon dioxide, and/or nitrous oxide.
b Emission factors exist for at least some air toxics.
cOAP staff stated that if a methane emission factor exists for a process and the gas constituents of the well are
known, then VOCs and air toxics can be calculated.
We identified 495 existing emission factors for oil and gas production in
WebFIRE. Of the 495 emission factors, 75 percent (371) are for internal
combustion engines and 22 percent (111) are for process heaters (including steam
generators). Except for GHGs, we did not identify any existing emission factors
for produced water tanks, well completions, or pneumatic devices. EPA needs to
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develop new emission factors for other sources besides internal combustion
engines and process heaters.
Many Existing Emission Factors Are of Low or Unknown Quality
Many of EPA's existing WebFIRE oil and gas production emission factors are of
questionable quality because they are based on limited and/or low quality data.
Each emission factor in WebFIRE! receives a ranking of 'A' (Excellent) through
'E' (Poor), or is unrated by OAQPS. A key aspect of the ranking of the emission
factors is the amount of data upon which an emission factor is based.14 An
emission factor is ranked higher if it is based on a larger amount of high quality
data and is ranked lower if it is based on a smaller amount of lesser quality data.
As shown in table 4, about half of EPA's emission factors for oil and gas
production in WebFIRE (248 of 495) are rated below average or poor, or are
unrated. This means they are based on limited or insufficient data.
Table 4: Ratings for EPA's oil and gas production emission factors
Emission factor rating
No. of emission factors
Percentage of emission
factors
A - Excellent
86
17%
B - Good
29
6
C - Average
132
27
D - Below Average
53
11
E - Poor
83
17
U - Unrated
112
23
Total
495
101%a
Source: OIG-developed table from EPA's WebFIRE database.
aTotal not equal to 100 percent due to rounding.
Although half of the oil and gas production emission factors we reviewed were
rated below average or were unrated, this is slightly better than what we reported
for all emission factors in the 2006 EPA OIG report, EPA Can Improve Emissions
Factors Management and Development. In that report, we noted that the percentage
of all AP-42 emission factors15 rated below average or poor was 62 percent.
State agencies and facility owners/operators may use lower ranking emission
factors in decision-making when no other data on the source are available. For
example, one state agency recommends that the facilities in its state calculate
emissions for their permits using 18 different emission factors that are rated below
average or lower. Emission factors are the least expensive method of estimating
emissions.
14 EPA uses other criteria in the rating process. For example, EPA also looks at how well the data represents the
industry.
15 The OIG reported on all AP-42 emission factors in its 2006 report, not just oil and gas production emission
factors.
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EPA Has Developed a Tool to Collect Data, But Gaps Remain
EPA has developed the ERT for criteria and air toxic pollutants, which provides
an electronic format for facilities to document source test results. EPA's
WebFIRE database will be able to store the data that has been submitted
electronically. According to the revised 2012 NSPS and NESHAP rules for the oil
and gas sector, the overall quality of the existing and newly developed emission
factors will greatly improve by supplementing the pool of emissions test data and
by ensuring that the factors are more representative of current industry operational
procedures.
Starting in January 2012, facility owners or operators subject to certain EPA
regulations, including those of oil and gas operations, are required to submit
selected source test data directly to EPA. EPA is developing amendments to
existing rules to require similar electronic reporting requirements for rules codified
in 40 CFR Parts 60, 63, and 65. It is important to note that the requirement to report
data electronically only applies to data collected with a test method supported by
the ERT and only if the regulation requires its collection. For example, the final
2012 NSPS and NESHAP rules for the oil and gas sector require electronic
reporting of specific source tests. While the ERT may improve EPA's data from
some sources, the rules do not require source tests for all processes and sources
covered by the rules, such as combustors. Therefore, the results of any source tests
performed on combustors are not required to be reported electronically to EPA.
Thus, EPA will likely not receive this data and the rule will not contribute to the
improvement of emission factors for these sources.
Developing New Emission Factors and Improving Existing Emission
Factors Will Lead to Better Information to Make Key Decisions
Developing new emission factors and improving existing ones could significantly
enhance the information that EPA and the states have to make key decisions. For
example, in the technical support document for Subpart W of the GHG Reporting
Rule16, EPA revised the methane emission factors for well completions and
workovers. For unconventional well completions, the emission factor went from
0.02 metric tons/year to 177 metric tons/year (8,849 times greater). For
unconventional well workovers, the emission factor increased from 0.05 metric
tons/year to 177 metric tons/year (3,539 times greater).17
Oil and Gas Production Emissions Data in EPA's NEI Are Incomplete
Emissions data for oil and gas production in EPA's NEI are incomplete,
particularly for smaller sources and for air toxics. The Air Emissions Reporting
1640 CFR งง 98.230 to 98.238.
17 The 2006 GHG Inventory increase was also due in part to the revision in the liquids unloading emission factor.
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Requirements (AERR)18 rule requires states to report emissions of criteria
pollutants and ozone precursors (e.g., VOCs) from a variety of sources to EPA's
NEI. These sources include large stationary sources called point sources,19 small
stationary sources called nonpoint sources, and mobile sources. States are not
required to report air toxic emissions, although some do voluntarily. Emissions
from point sources are reported on a facility-specific basis. Emissions from
nonpoint sources can be based on estimates and aggregated by industry sector at
the county level. Examples of point sources in the oil and gas sector are gas
processing plants and compressor stations. Examples of nonpoint sources include
smaller, upstream sources and processes, such as well production pads.
Nonpoint sources are significant sources of emissions in the oil and gas production
industry. However, few states submitted data on these sources to EPA for inclusion
in the most recent 2008 NEI. While 35 states submitted oil and gas production
emissions data for point sources to the 2008 NEI, only 9 submitted emissions data
for nonpoint sources.20 Meanwhile, emissions from these smaller sources accounted
for the majority of total oil and gas emissions in the 2008 NEI. For example,
nonpoint sources accounted for 98 percent of all oil and gas VOC emissions in the
2008 NEI, while larger point sources accounted for only 2 percent. Due to the
cumulatively high emissions from this collection of smaller sources and the limited
reporting of emissions from these sources, the NEI likely underestimates actual
criteria pollutant emissions from oil and gas production sources.
Data for air toxic emissions in the NEI are also incomplete. Of the 35 states that
submitted oil and gas production emissions data to the 2008 EPA NEI, 12 states
did not report air toxic data for point sources and 32 states did not report air toxic
data for nonpoint sources. Given the lack of air toxic data in the NEI, particularly
for nonpoint sources, these emissions are also most likely understated in the NEI.
As stated above, the AERR does not require states to report air toxic data to the
NEI.
EPA Efforts to Fill Data Gaps for Specific Decision-Making Purposes
EPA has adjusted existing NEI data to fill significant gaps for specific decision-
making purposes. For example, in conducting its 2011 regulatory impact
assessment for the proposed revised NSPS and NESHAP rules, EPA found that
18
The AERR replaced the requirements of the Consolidated Emissions Reporting Rule, which was in effect at the
time the data for the 2008 NEI were collected. The Consolidated Emission Reporting Rule also required states to
report emissions of criteria pollutants and ozone precursors (e.g., VOCs) from both large stationary sources, small
stationary sources, and mobile sources to EPA for purposes of developing the NEI.
19 Point sources are stationary sources that have the potential to emit criteria pollutants, VOCs, and ammonia at
levels at or above specific thresholds. Nonpoint sources are stationary sources that do not meet the emission
thresholds for point sources.
20 Some states may report some nonpoint source data emissions as point source data emissions. This is especially
true in states that have their own reporting requirements and regulations for oil and gas facilities that are more
stringent than EPA's regulations. In these cases, emissions that would otherwise be included in the nonpoint
emissions inventory are actually included in the point source inventory.
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emissions data for well completions were significantly undercounted in the 2008
NEI. EPA found that the 2008 NEI contained only about 21,000 tons of VOC
emissions from well completions. In contrast, EPA estimated as part of its
engineering analysis for the 2011 proposed NSPS and NESHAP rulemaking that
well completions emit about 510,000 tons of VOCs a year. This amount was
nearly 25 times as much as had previously been contained in EPA's 2008 NEI. As
a result, EPA added about 480,000 tons of VOC emissions to the 2008 NEI in
order to develop a baseline for VOC emissions.
In another example, while conducting a residual risk assessment of facilities
covered by the existing NESHAP rules for oil and gas, EPA found that 75 percent
of the facilities did not have emissions data for key air toxics, which include
benzene, toluene, ethylbenzene, and xylenes, in the NEI. In the absence of these
data, EPA developed air toxic estimates by applying certain percentage ratios to
facilities' reported VOC emissions. EPA then assigned these surrogate emission
estimates to the facilities with missing air toxic data.
In addition, EPA has augmented existing oil and gas data in the NEI for air
modeling purposes. Specifically, OAQPS staff incorporated emissions data from
the 2006 Western Regional Air Partnership inventory in its most recent modeling
platform to support regulatory analyses. OAQPS staff told us that EPA hired a
contractor to identify and obtain all available oil and gas emissions data that are
not already in the NEI. However, EPA staff said the only data the contractor
identified were the Western Regional Air Partnership data.
Multiple Factors Contribute to Oil and Gas Data Gaps in the NEI
The following factors contribute to the oil and gas emissions data gaps in the NEI:
EPA has not developed default emission estimates for oil and gas
nonpoint sources. For the 2008 NEI, EPA developed default emission
estimates for 76 types of nonpoint sources for selected industry sectors
that could be used in the absence of state-reported data. However, the oil
and gas production sector was not among those 76 categories. Thus,
nonpoint emissions for oil and gas remained "0" in the NEI if states did
not submit data. According to OAQPS staff, EPA has not developed a
default emission methodology for the oil and gas production sector
because the sector was not as large prior to 2008. OAQPS staff also stated
that developing such a methodology in time for the 2008 NEI was not
feasible because (1) resources had been diverted to the Agency's transition
to the Emissions Inventory System for the 2008 NEI, (2) the industry grew
significantly during this time, and (3) there was a lack of emission factors
data on new exploration methods.
According to OAQPS staff, EPA has formed a national workgroup of oil and
gas sector experts to develop default emissions estimates. The workgroup has
written a white paper outlining an approach for creating a national default
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method that would allow for variability by basin. According to EPA, OAQPS
has allocated $85,000 to develop default emissions estimates from the
nonpoint upstream oil and gas sector. This tool will have the capability to
estimate 2011 and future year emissions on the county level for criteria
pollutants, HAP, ammonia, and GHGs. According to OAQPS staff, states can
either accept the default estimates developed by EPA or can submit their own
emissions data to the NEI.
EPA has not ensured state submission of nonpoint source oil and gas
data as required by AERR. As discussed above, only nine states
submitted emissions data for nonpoint oil and gas sources. OAQPS staff
stated that they have not reviewed states' submissions from a compliance
standpoint. Instead, OAQPS staff tries to influence states to submit data so
that the emissions inventory is complete.
Some states are not collecting emissions data from smaller (i.e.,
nonpoint) oil and gas production facilities due to a lack of permitting
requirements. According to OAQPS staff, some states do not have data to
submit to the NEI because they do not have regulations in place to require
small facilities to be permitted. In states where these smaller sources are
unpermitted and/or unregulated, states are not likely to obtain emissions
data from these sources to submit to the NEI.
Developing a robust inventory that would cover these numerous
small, unregulated sources is resource intensive. This is particularly
true for emission sources and processes that do not have established
emission factors or other estimation techniques that the states can use to
estimate emissions.
Incomplete NEI Data Affect EPA's Ability to Assess Risks and Air
Quality Impacts from Oil and Gas Production Emissions
EPA uses the NEI to assess risks from air toxics through its National Air
Toxics Assessment (NATA) and to model air quality in support of regulatory
impact assessments for National Ambient Air Quality Standards (NAAQS)21 rules
and revisions. Without complete emissions data, EPA cannot accurately assess
risks and air quality impacts associated with oil and gas production emissions.
The NATA provides broad estimates of cancer risk and other serious health
effects resulting from air toxics. Modeling conducted for the NATA relies
primarily on air toxic emissions data in the NEI. If air toxic emissions data for oil
and gas activities are not included in the NEI, potential risks from these emissions
will not be identified in the NATA.
21 NAAQS establish maximum permissible concentrations of criteria pollutants in the air. The ozone NAAQS is of
concern for the oil and gas production industry because oil and gas production activities emit significant amounts of
VOCs, which contribute to the formation of ozone.
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In order to demonstrate progress towards NAAQS attainment, or show maintenance
of the NAAQS once attained, states need to conduct air quality modeling pertaining
to the NAAQS. This is particularly true for ozone, as oil and gas production
activities emit significant amounts of VOCs and NOx that contribute to ozone
formation. For example, a staff person responsible for ozone modeling from a state
air control agency said his agency has to rely on NEI data from other states in
conducting ozone modeling to represent the transport of ozone-forming pollutants.
Incomplete emissions data, such as the gaps described above for nonpoint sources,
will lead to modeling results that underestimate the air quality impacts from oil and
gas production activities.
Limited Data Could Affect Decision-Making Impacting Human Health
and the Environment
Directly measured data, including source test data, provide EPA with the most
accurate information to develop new emission factors and improve existing
emission factors. Limited data and limited emission factors impact the
development of SIPs. The CAA requires states that fail to meet NAAQS to develop
SIPs that describe how the state will attain and maintain the NAAQS. EPA then
evaluates SIPs to determine whether states have proper control strategies in place
to achieve attainment. To properly develop and evaluate SIPs, EPA and states need
emissions data and emission estimates to understand air emissions from the oil and
gas production sector. In areas with high oil and gas production activity, emissions
from this industry may significantly affect ozone levels and attainment of the ozone
NAAQS. Without adequate data and emission estimates for oil and gas emissions,
states may rely on industry sectors other than oil and gas production to obtain
emission reductions. EPA may then approve SIPs that place an inequitable burden
on industries other than oil and gas production. Limited data could affect decision-
making impacting human health and the environment.
Conclusions
Recent and projected growth in the oil and gas production sector has underscored
the need for EPA to gain a better understanding of emissions and potential risks
from this industry sector. Harmful pollutants emitted from this industry include
air toxics such as benzene, toluene, ethylbenzene, and xylene; criteria pollutants
and ozone precursors such as NOx and VOCs; and greenhouse gases such as
methane. These pollutants can result in serious health impacts such as cancer,
respiratory disease, aggravation of respiratory illnesses, and premature death.
However, EPA has limited directly-measured air emissions data on criteria and
toxic air pollutants for several important oil and gas production processes. This
limited data, coupled with poor quality and insufficient emission factors and
incomplete NEI data, hamper EPA's ability to assess air quality impacts from
selected oil and gas production activities.
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EPA is currently engaging in efforts to collect additional emissions data, but these
studies have been limited in scope and future funding is uncertain. The Agency
does not have a comprehensive, cross-office strategy for prioritizing air emissions
data needs and developing action plans to address those needs. In our view, a
comprehensive strategy would help EPA better manage the collection of needed
data on air emissions from the oil and gas production sector.
Recommendations
We recommend that the Assistant Administrator for Air and Radiation and the
Assistant Administrator for Research and Development:
1. Develop and implement a joint comprehensive cross-office strategy for
improving data for the oil and gas production sector. The strategy should:
a. Identify gaps and limitations in (1) existing oil and gas air
emissions data, (2) emission factors, and (3) measurement
techniques, including direct and remote measurement methods.
b. Prioritize what data limitations are most significant and develop
specific action plans for how EPA will address these gaps and
limitations.
We recommend that the Assistant Administrator for Air and Radiation:
2. Prioritize and update existing oil and gas production emission factors that are
in greatest need of improvement and develop emission factors for key oil and
gas production processes that do not currently have emission factors.
3. Ensure that the data in NEI are complete by:
a. Monitoring the states' submission of oil and gas emissions data for
point sources and nonpoint sources pursuant to the requirements of
the AERR and assisting states in complying with the rule.
b. Completing the development of a method for calculating default
nonpoint emission estimates to enter into the NEI when states do
not submit nonpoint data for oil and gas production.
c. Developing default calculation guidance for states to use to
estimate oil and gas nonpoint source emissions.
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Agency Comments and OIG Evaluation
The Agency concurred with our recommendations 1, 2, and 3b to develop a
comprehensive strategy, prioritize and develop emission factors, and develop a
default method for calculating nonpoint emissions, respectively. The Agency did
not provide milestone dates or identify the responsible party for implementing the
planned corrective actions for these recommendations and, as such, they are
considered unresolved pending receipt of this information. The OIG and the
Agency have not agreed on a course of action to remedy and/or address
recommendations 3a and 3c. These recommendations are unresolved pending the
Agency's final report response. Appendix A contains the Agency's response to our
draft report. Appendix B contains our detailed evaluation of that response.
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Status of Recommendations and
Potential Monetary Benefits
RECOMMENDATIONS
POTENTIAL MONETARY
BENEFITS (In $000s)
Rec.
No.
Page
No.
Subject
Status1
Action Official
Planned
Completion
Date
Claimed
Amount
Ag reed-To
Amount
21 Develop and implement a joint comprehensive
cross-office strategy for improving data for the oil
and gas production sector. The strategy should:
a. Identify gaps and limitations in (1) existing oil
and gas air emissions data, (2) emission
factors, and (3) measurement techniques,
including direct and remote measurement
methods.
b. Prioritize what data limitations are most
significant and develop specific action plans
for how EPA will address these gaps and
limitations.
21 Prioritize and update existing oil and gas
production emission factors that are in greatest
need of improvement and develop new emission
factors for key oil and gas production processes
that do not currently have emission factors.
21 Ensure that the data in NEI are complete by:
a. Monitoring the states' submission of oil and
gas emissions data for point sources and
nonpoint sources pursuant to the
requirements of the AERR and assisting
states in complying with the rule.
b. Completing the development of a method for
calculating default nonpoint emission
estimates to enter into the NEI when states
do not submit nonpoint data for oil and gas
production.
c. Developing default calculation guidance for
states to use to estimate oil and gas nonpoint
source emissions.
Assistant Administrator for
Air and Radiation and
Assistant Administrator for
Research and Development
Assistant Administrator for
Air and Radiation
Assistant Administrator for
Air and Radiation
0 = recommendation is open with agreed-to corrective actions pending
C = recommendation is closed with all agreed-to actions completed
U = recommendation is unresolved with resolution efforts in progress
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Appendix A
Agency Comments on Draft Report
November 16, 2012
MEMORANDUM
SUBJECT: Response to Draft Report, EPA Needs to Improve Air Emissions Data for the Oil
and Natural Gas Production Sector, Proj ect No. OPE-F Y11 -0010
FROM: Gina McCarthy
Assistant Administrator
Office of Air and Radiation (OAR)
Lek G. Kadeli
Deputy Assistant Administrator
Office of Research and Development (ORD)
TO: Carolyn Copper
Assistant Inspector General for Program Evaluation
Office of Inspector General (OIG)
Thank you for the opportunity to comment on the OIG draft report, EPA Needs to Improve Air
Emissions Data for the Oil and Natural Gas Production Sector, Project No. OPE-F Y11-0010,
dated September 26, 2012. This review was initiated to determine whether OAR and ORD could
improve air emissions data necessary for making key decisions associated with oil and natural
gas production processes, including the need for regulations, and enforcement and permitting
decisions.
We appreciate the OIG's efforts to gain a thorough understanding of the complexity of the oil
and natural gas production sector and the many emission sources and pollutants involved. The
OIG review makes several recommendations regarding ways in which OAR and ORD can
improve the EPA's body of knowledge on air emissions from this sector. These
recommendations, along with our responses, are presented below. Additional comments
pertaining to the draft report text are attached in a separate document.
Recommendation 1: We recommend that the Assistant Administrator for Air and Radiation
and the Assistant Administrator for Research and Development:
1. Develop and implement a joint comprehensive cross-office strategy for improving data for the
oil and gas production sector. The strategy should:
a. Identify gaps and limitations in
(1) existing oil and gas air emissions data;
(2) emission factors; and
(3) measurement techniques, including direct and remote measurement methods.
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b. Prioritize what data limitations are most significant and develop specific action plans
for how EPA will address these gaps and limitations.
Response: We concur with this recommendation and will take the necessary steps to develop a
cross-office strategy. Implementing such a strategy will be contingent upon the availability of
future resources.
We have identified emissions information for oil and natural gas production as a critical need
and, as a result, have several ongoing activities that informally address the key OIG
recommendations for a data improvement strategy. For example, OAR, ORD, and several
Regional Offices have been working together over the past few years to develop methods and
collect data on emissions from oil and natural gas production operations. In addition, EPA's
Greenhouse Gas (GHG) Reporting Program was developed in coordination with offices across
EPA and will provide comprehensive GHG emissions data for oil and natural gas systems across
the U.S. Further, EPA is partnering with other federal agencies, specifically the Department of
Energy and the Department of Interior, under a 2013 initiative focusing on unconventional oil
and natural gas development. This collaborative effort is planned to provide emissions, exposure
and effects information related to the growing use of hydraulic fracturing to increase domestic
yields of natural gas and, more recently, oil. We can use these efforts as the basis for a formal,
written cross-office strategy.
With regard to a formal cross-office strategy, ORD and OAR will build on work already under
way or completed to develop and implement a strategy for improving data. The offices will
establish a dedicated cross-office team to:
1) describe in detail gaps and limitations identified in ongoing agency research planning
activities;
2) leverage existing data sources;
3) prioritize the data limitations; and
4) propose actions to address data gaps and limitations, beginning with those considered as
highest priority.
Examples of some areas for which we have already identified a need for new or improved
emissions information include:
1) liquid unloading of gas wells (to be updated in the 2013 U.S. GHG Inventory);
2) hydraulically fractured oil wells;
3) hybrid (oil and natural gas) wells; and
4) evaporation ponds and pits.
In addition to our own efforts, we are following work being done by a number of outside
organizations and entities to identify and collect data that will be useful in better characterizing
emissions and will further inform our own studies in this sector. These entities include regional
planning organizations, states, industry, environmental groups and academic institutions. For
example, we are tracking studies being carried out by the Central Regional Air Planning
Association (CENRAP), the Western Regional Air Partnership (WRAP), and several states that
may provide potentially valuable data on this sector.
See Appendix B, Note 1, for OIG Response
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Recommendation 2: We recommend that the Assistant Administrator for Air and Radiation:
2. Prioritize and update existing oil and gas production emission factors that are in greatest
need of improvement and develop emission factors for key oil and gas production processes that
do not currently have emission factors.
Response: We agree that emission factors should be reviewed for oil and natural gas production
processes and revised as appropriate. We are developing an e-reporting program to expedite the
development of emission factors for all industrial source categories. We have made substantial
progress and have begun incorporating into our regulations requirements that affected sources
submit certain data to us electronically. This includes a requirement to report electronically the
results of emission tests when they are conducted on certain emission points covered in the
recently promulgated oil and natural gas rules.
We recognize the recent interest and new data available (with more data coming) on several key
sources in the natural gas sector, particularly natural gas production. The Inventory of U.S.
Greenhouse Gas Emissions and Sinks annual development process results in updates to
emissions factors on an ongoing basis and we will continue to improve our estimates as new data
become available.
See Appendix B, Note 2, for OIG Response
Recommendation 3: We recommend that the Assistant Administrator for Air and Radiation:
3. Ensure that the data in National Emissions Inventory (NEI) is complete by:
a. ensuring that states submit point source and nonpoint source data pursuant to the Air
Emissions Reporting Requirements (AERR) ride;
b. completing the development of a methodfor calculating default nonpoint emission
estimates to enter into the NEI when states do not submit nonpoint data for oil and
gas production; and
c. developing default calculation guidance for states to use to estimate oil and gas
nonpoint source emissions.
Response (3a): We concur that having a complete NEI is in the best interest of the agency and
the public; however, we are concerned that this recommendation (as worded) suggests that states
are not complying with the AERR rule reporting requirements. Our experience is that states
comply with the AERR rule and send emission data to EPA when it is available to them. Data
from the oil and gas sector is becoming increasingly available, and we expect the states will
submit more data to us. Limited state resources and the lack of data availability have contributed
to past data gaps. However, the emissions tool described in our response to Recommendation 3b
below will largely resolve emissions data gaps for this sector. Changing the word "ensure" in this
recommendation to "encourage and assist" would greatly improve this recommendation.
See Appendix B, Note 3, for OIG Response
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Response (3b): We concur and continue to pursue the development of a tool for calculating
nonpoint emissions for oil and natural gas production. We intend to have a draft tool available
during early 2013 for estimation of emissions in the 2011 NEI. We will continue to enhance the
tool, as resources allow, for future NEI versions. Annual oil and natural gas activity updates to
the tool are possible and would require purchase of an industry database for $3OK per year.
Additional improvements require additional resources.
See Appendix B, Note 4, for OIG Response
Response (3c): We agree that states need more information on estimating emissions from this
sector, but we disagree that a "guidance document" will have additional benefit over the tool
described in our response to recommendation 3b. Producing a separate guidance document will
create an additional resource burden on EPA to keep the tool and guidance document in sync.
These resources can be better used updating the tool. If out of sync, two separate sources of
disparate information will add confusion, not clarity. Therefore, we believe that the tool
described in our response to Recommendation 3b and the associated documentation are sufficient
for meeting the needs of this recommendation. This recommendation could be improved by
acknowledging that the tool with appropriate documentation can effectively serve as sufficient
guidance.
See Appendix B, Note 5, for OIG Response
Again, we appreciate the efforts undertaken by the OIG to conduct a thorough review and to
provide recommendations for improvement of the EPA's information on air emissions from the
oil and natural gas production sector. Please feel free to contact us with any questions.
Attachment
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Appendix B
OIG Evaluation of Agency Comments
We appreciate the Agency's comments and its recognition of our efforts to gain a thorough
understanding of the complexity of the oil and natural gas production sector. Our comments
concerning the draft report recommendations are below. We also received a number of technical
comments from the Agency and made changes to the final report as appropriate.
Note 1- Response to Recommendation 1:
The Agency concurred with our recommendation to develop and implement a joint
comprehensive cross-office strategy for improving data for the oil and gas production sector.
However, it stated that such implementation would be contingent upon the availability of future
resources. We understand that resources are limited, but our report reflects the need for the
Agency to make the oil and gas production sector a priority. Indeed, the Agency states that it has
identified emissions information for this industry as a "critical need" and has several efforts
underway to informally address our recommendations. These efforts include a cross-office work
group on developing methods to measure emissions, the Greenhouse Gas Reporting Program,
and interagency collaboration on unconventional oil and natural gas development. The Agency
states that it commits to establishing a cross-office team to undertake tasks that will build the
foundation for a comprehensive strategy. We agree with these planned actions and recommend
that the Agency provide the timeframes for completing these tasks, as well as the party/office
responsible for the corresponding recommendations, in its response to the OIG final report. We
consider this recommendation unresolved pending receipt of this information.
Note 2 - Response to Recommendation 2:
EPA agreed that emission factors should be reviewed for oil and natural gas production
processes and revised as appropriate. The Agency clarified in the exit conference that it
concurred with recommendation 2. In our view, the recent and projected growth in this industry
sector establishes the need to prioritize emissions factor improvements for this sector over other
stable or dwindling industry sectors. Additionally, the Agency discusses the development of an
e-reporting program to support emission factor development. As stated in the OIG draft report,
the requirement to report data electronically only applies to data collected with a test method
supported by the ERT and only if the regulation requires its collection. Therefore, certain sources
that may need new or updated emission factors are not currently addressed by the ERT. In the
Agency's final response, it will need to provide the estimated completion dates and the
responsible party/office. We consider this recommendation unresolved pending receipt of this
information.
Note 3 - Response to Recommendation 3a:
The Agency disagreed with the language the OIG uses in recommendation 3a, "Ensuring that
states submit point source and nonpoint source data pursuant to the AERR." As stated in the OIG
draft report, only nine states submitted emissions data for nonpoint oil and gas sources. We do
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not agree with the Agency's recommendation to change the word "ensuring" to "encourage and
assist." We believe that the Agency should monitor states' submissions of the data pursuant to
the AERR and assist states in complying with the rule. We revised this recommendation
accordingly. The Agency should further discuss how they will use the tool described in their
response to recommendation 3b to help states submit the required data. We consider this
recommendation unresolved.
Note 4: Response to Recommendation 3b:
The Agency concurred with recommendation 3b and provided details of the corrective actions it
has ongoing and planned. EPA is developing a method for calculating default nonpoint emission
estimates for the NEI and intends to have a draft tool ready in early 2013. Specifically, EPA
noted that it plans to have a draft tool available during 2013 for estimation of emissions in the
2011 NEI, and that it will continue to enhance the tool, as resources allow, for future NEI
versions. We accept the Agency's planned corrective actions in response to this
recommendation. In the Agency's final response, the Agency will need to provide the OIG with
estimated completion dates and the responsible party/office for its planned actions. We consider
this recommendation unresolved pending receipt of this information.
Note 5: Response to Recommendation 3c:
The Agency disagrees that states need a separate guidance document aside from the tool and
associated documents from recommendation 3b. In our view, it is pivotal that state users have the
guidance needed to implement the tool created in response to recommendation 3b. When we
review the Agency's final response for recommendation 3b, we will assess whether the
associated documentation planned for the tool described in the Agency's response to
recommendation 3b meets the intent of recommendation 3c. We consider this recommendation
unresolved.
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Appendix C
Growth in Oil and Gas Production Industry
Natural gas production has increased greatly over the past two decades. Much of this growth is
due to recent development of natural gas from shale formations.
The growth in natural gas production has been most pronounced in areas of the United States
covered by EPA Regions 3, 6, and 8. Region 3 includes the recently developed high-growth area
of the Marcellus Shale. Region 6 encompasses numerous high-producing areas in Texas,
Louisiana, Oklahoma, and New Mexico, including the Barnett Shale and Haynesville Shale.
High-producing areas covered by Region 8 include the Uinta Basin in Utah and the Denver-
Julesberg Basin in Colorado. Figure C-l shows the number of producing gas wells in 1992 and
2010 by EPA region. As shown, the number of wells increased in all regions, with the largest
increases in Regions 3, 6, and 8.
Figure C-1: Number of producing natural gas wells by EPA Region, 1992-2010
Source: OIG-developed graph based on data from the EIA.
Note: The states covered by each EPA region are as follows: Region 2: New Jersey and New York;
Region 3: Delaware, Washington DC, Maryland, Pennsylvania, Virginia, and West Virginia;
Region 4: Alabama, Georgia, Florida, Kentucky, Mississippi, North Carolina, South Carolina, and
Tennessee; Region 5: Illinois, Indiana, Michigan, Minnesota, Ohio, and Wisconsin; Region 6:
Arkansas, Louisiana, New Mexico, Oklahoma, and Texas; Region 7: Iowa, Kansas, Missouri, and
Nebraska; Region 8: Colorado, Montana, North Dakota, South Dakota, Utah, and Wyoming;
Region 9: Arizona, California, Hawaii, and Nevada; Region 10: Alaska, Idaho, Oregon, and
Washington. There are no gas-producing states in Region 1, which includes Connecticut,
Massachusetts, Maine, New Hampshire, Rhode Island, and Vermont.
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EIA projects that production of both natural gas and crude oil will increase steadily in the future.
Figure C-2 shows the projected growth for crude oil production while Figure C-3 shows the
projected growth in natural gas production from 2009 to 2025.
Figure C-2: Estimated increase in crude oil production and supply, 2009-2025
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Appendix D
Final Revised 2012 NSPS and NESHAP Rules
On April 17, 2012, EPA issued revisions to the existing NSPS and NESHAPs rules for the oil
and gas industry. EPA's review and revision of the existing rules were conducted in response to
a lawsuit filed against the Agency for failing to meet certain provisions of the CAA that require
periodic review of NSPS and NESHAP rules. The new revisions will require emission controls
and reductions for several types of oil and gas sources and processes that are not currently
controlled by the existing rules. These include the following:
NSPS Revisions
> Well Completions at New Hydraulically Fractured Gas Wells (VOC reductions): The new
rules include a two-phased approach for controlling VOCs from these completions:
During Phase 1 (before January 1, 2015), operators must reduce VOC emissions by
(1) flaring using a combustion device, or (2) capturing the gas using green
completions with a combustion device.
During Phase 2 (starting January 1, 2015), operators are required to conduct green
completions at all new hydraulically fracked wells, except for new exploratory and
delineation wells, and hydraulically fractured low-pressure wells. For those wells,
combustion of the gas is required, unless combustion would cause a safety hazard or
is prohibited by state or local regulation.
> Well Completions at Refractured Gas Wells (VOC reductions): Operators may reduce
emissions through flaring until January 15, 2015. After that date, they must use green
completions.
> Pneumatic Devices (VOC reductions): For pneumatic devices at the well site and at gathering
and boosting stations, the rule sets a gas bleed limit of 6 standard cubic feet per hour.
> Centrifugal Compressors (VOC reductions): The new revised rule requires a 95 percent
reduction in VOC emissions from compressors with wet seal systems, which can be
accomplished through flaring or by routing captured gas back to a compressor suction or fuel
system.
> Reciprocating Compressors (VOC reductions): The new revised rule requires the replacement
of the rod packing (1) after every 26,000 hours of operation, or (2) every 36 months.
> Storage Vessels (VOC reductions): New storage tanks with VOC emissions of 6 tons a year
or more must reduce VOC emissions by at least 95 percent, which will generally be
accomplished by routing emissions to a combustion device.
> Leak Detection and Repair at Gas Processing Plants (VOC reductions): The new revi sed
rule includes strengthened leak detection and repair at processing plants.
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> Sweetening Units at Gas Processing Plants (SO 2 reductions): Sweetening units with a sulfur
production rate of at least five long tons per day are required to reduce SO2 emissions by
99.9 percent.
NESHAP Revisions
> Glycol Dehydrators (HAP reductions): Emissions limits for benzene, toluene, ethylbenzene,
and xylene will apply to existing and new smaller dehydrators.
The NSPS revisions will generally apply only to new sources in the industry, while the NESHAP
revisions will apply to all new and existing sources that meet the emissions thresholds for major
sources of Hazardous Air Pollutant emissions.22 EPA estimates that the new revised NSPS and
NESHAP rules will result in reductions of 190,000 tons of VOCs, 12,000 tons of Hazardous Air
Pollutants, and 1 million tons per year of methane.
22 "Major sources" are sources that emit or have the potential to emit 10 tons per year of a single HAP, or 25 tons
per year or more of any combination of Hazardous Air Pollutants.
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Appendix E
Descriptions of Equipment and Processes for
Oil and Gas Production
Equipment or process
Description of equipment or process
Compressor
Any machine that raises the pressure of gas or carbon dioxide by drawing
in low pressure gas or carbon dioxide and discharging significantly higher
pressure gas or carbon dioxide.
Condensate
Hydrocarbon and other liquids, including both water and hydrocarbon
liquids, separated from gas that condense due to changes in the
temperature, pressure, or both, and remain liquid at storage conditions.
Dehydrator
A device in which a liquid absorbent (including desiccant, ethylene glycol,
diethylene glycol, ortriethylene glycol) directly contacts a gas stream to
absorb water vapor.
Glycol dehydration unit
A device in which a liquid glycol absorbent directly contacts a gas stream
and absorbs water in a contact tower or absorption column (absorber).
Horizontal drilling
The process of drilling and completing, for production, a well that begins
as a vertical or inclined linear bore which extends from the surface to a
subsurface location just above the target oil or gas reservoir. The well
then bears off on an arc to intersect the reservoir at the "entry point," and,
thereafter, continues at a near-horizontal attitude tangent to the arc, to
substantially or entirely remain within the reservoir until the desired
bottom hole location is reached.
Hydraulic fracturing
(also referred to as
"tracking")
The 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 flowbackto expel fracture fluids and solids during completions.
Internal combustion
The combustion of a fuel that occurs with an oxidizer (usually air) in a
combustion chamber. In an internal combustion engine, the expansion of
the high-temperature and high-pressure gases produced by combustion
applies direct force to a component of the engine, such as pistons, turbine
blades, or a nozzle. This force moves the component over a distance,
generating useful mechanical energy. Internal combustion equipment may
include gasoline and diesel industrial engines, natural gas-fired
reciprocating engines, and gas turbines.
Pneumatic Devices
High-bleed pneumatic devices - Automated, continuous bleed flow
control devices powered by pressurized gas and used for maintaining a
process condition such as liquid level, pressure, and temperature. Part of
the gas power stream that is regulated by the process condition flows to a
valve actuator controller where it vents continuously (bleeds) to the
atmosphere at a rate in excess of 6 standard cubic feet per hour.
Intermittent bleed pneumatic devices - Automated flow control devices
powered by pressurized gas and used for maintaining a process condition
such as liquid level, pressure, and temperature. These are snap-acting or
throttling devices that discharge the full volume of the actuator
intermittently when control action is necessary, but does not bleed
continuously.
Low-bleed pneumatic devices - Automated flow control devices powered
by pressurized gas and used for maintaining a process condition such as
liquid level, pressure, and temperature. Part of the gas power stream that
is regulated by the process condition flows to a valve actuator controller
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where it vents continuously (bleeds) to the atmosphere at a rate equal to
or less than 6 standard cubic feet per hour.
Produced water
Water that is extracted from the earth from an oil or gas production well,
or that is separated from crude oil, condensate, or gas after extraction.
Produced water
evaporative ponds
Ponds usually with a large surface area that contain produced water,
which is allowed to evaporate from the surface.
Production casing
The deepest section of casing in a well. Well casing consists of a series of
metal tubes installed in a freshly-drilled hole. Casing strengthens the
sides of the well hole, ensures that no oil or gas seeps out of the well hole
as it is brought to the surface, and keeps other fluids or gases from
seeping into the formation through the well. Production casing is installed
last. This is the casing that provides a conduit from the surface of the well
to the petroleum-producing formation.
Production well
A hole drilled in the earth from which crude oil, condensate, or field gas is
extracted.
Pump
A device used to raise pressure, drive, or increase flow of liquid streams
in closed or open conduits.
Separator
A vessel in which streams of liquid of multiple phases are gravity-
separated into individual streams of single phase.
Sour gas
Gas that contains significant concentrations of hydrogen sulfide and/or
carbon dioxide that exceed the concentrations specified for commercially
saleable natural gas delivered from transmission and distribution
pipelines.
Sweet gas
Gas with low concentrations of hydrogen sulfide and/or carbon dioxide
that does not require (or has already had) acid gas treatment to meet
pipeline corrosion-prevention specifications for transmission and
distribution.
Well completions
The process that allows for the flow of petroleum or natural gas from
newly-drilled wells to expel drilling and reservoir fluids and test the
reservoir flow characteristics. These steps may vent produced gas to the
atmosphere via an open pit or tank. Well completion also involves
connecting the well bore to the reservoir, which may include treating the
formation or installing tubing, packer(s), or lifting equipment. These steps
do not significantly vent natural gas to the atmosphere. This process may
also include high-rate flowback of injected gas, water, oil, and proppant
used to fracture or re-fracture and prop open new fractures in existing
lower permeable gas reservoirs. These steps may vent large quantities of
produced gas to the atmosphere.
Sources: OIG developed table using GHG Technical Support Document; 1993 Department of Energy Information
Administration report entitled Drilling Sideways - A Review of Horizontal Well Technology and its Domestic
Application; 2009 Argonne National Laboratory Study entitled Produced Water Volumes and Management Practices
in the United States; final revised NSPS and NESHAP rules for the oil and gas industry issued April 2012; and
NaturalGas.org (production casing definition).
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Distribution
Office of the Administrator
Assistant Administrator for Air and Radiation
Assistant Administrator for Research and Development
Agency Follow-Up Official (the CFO)
Agency Follow-Up Coordinator
General Counsel
Associate Administrator for Congressional and Intergovernmental Relations
Associate Administrator for External Affairs and Environmental Education
Audit Follow-Up Coordinator, Office of Air and Radiation
Audit Follow-Up Coordinator, Office of Research and Development
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