Efforts to decrease emissions from the oil and gas industry
Methane is the main component of almost all natural gas, and gas delivered to end-users is purified to 95-98% methane.1 There are three main sources of methane emissions from the oil and gas industry:
- When a well is being drilled, cleaned out, or hydraulically fractured. As the fluids involved in these operations flow back up the well to the surface they bring methane with them, which can escape into the atmosphere.
- Through leaky equipment in wells, processing plants, and pipelines.
- When operators burn off (“flare”) or vent small amounts of methane produced from oil wells. This commonly occurs when the gas cannot be sold due to low quality or lack of pipeline access. Flaring converts methane to carbon dioxide, but venting directly emits methane into the atmosphere.
There is a strong environmental incentive to reduce emissions of methane: it is a potent greenhouse gas that traps much more heat per molecule than carbon dioxide.3 Methane in natural gas also coexists with a number of other organic compounds that contribute to the formation of ozone, which is harmful to plants and animals, including humans.4 Some efforts to reduce these kinds of emissions are voluntary;5 others are legally required by government regulations. Some regulations are enacted at the federal (national) level by the Environmental Protection Agency (EPA),6 while others are enacted and enforced by individual states.7 The EPA also supports voluntary programs to assist both the energy and agricultural industries in reducing their methane emissions.
Methane-related regulations include the use of “green” (reduced-emission) completions for gas wells, reduction of gas flaring, and leak monitoring and repair.
Uncaptured natural gas being flared off in the Bakken oil field, converting the methane to carbon dioxide. Image credit: Wikimedia Commons user Joshua Doubek.2
Green Completions of Oil and Gas Wells
Well “completion” involves all of the processes needed to get a well ready to produce oil and/or gas, including hydraulic fracturing. During these processes, mud and water from drilling and hydraulic fracturing (if used) flow back up the well to the surface along with some water contained in the oil- or gas-bearing rocks. This stream of fluids often brings oil and gas with it, and the gas has historically been allowed to escape into the atmosphere or flared off (see below). “Green” completions use specialized equipment to capture these gases and fluids.8 Captured methane may then be used on-site or sold.
Since 2015, the EPA has required that green completions be used for all hydraulically fractured natural gas wells.9 Prior to this, Wyoming, Colorado, and some cities in Texas had each implemented their own regulations requiring green completions, and some operators had voluntarily used green completions in other areas.9 As of 2018, the EPA regulations requiring green completions for oil wells are being considered for possible revisions.10
Reducing Natural Gas Flaring
In areas that produce mostly oil with small amounts of gas, operators often start moving the high-value oil to refineries before pipelines can be built to transport the less valuable natural gas. Instead, this gas is simply “flared,” i.e., burned in an open flame. This controlled burning prevents the buildup of flammable methane and converts methane to carbon dioxide – a less potent greenhouse gas. However, flaring wastes usable energy, increases the carbon footprint of the industry, and decreases the royalties that landowners – including private citizens and the government – could earn from the sale of this methane.
Flaring is typically most common in new areas of high oil production, and decreases as pipelines are built to transport the gas. For example, flaring was widely used in the rapidly growing Bakken area of North Dakota in the early-mid 2010s. From early 2014 to early 2016, flaring in North Dakota fell from 36% to 10% of produced gas as production fell (due to lower oil prices) and a local network of pipelines was constructed to collect the gas from individual wells.11
The Bureau of Land Management (BLM) issued a rule in November 2016 that limited flaring on federal lands.13 In late 2017, parts of this rule were temporarily suspended or delayed until January 2019, pending review of the rule by BLM.
Natural gas infrastructure includes a large number of valves and connectors, such as at this gas processing facility in Montgomery County, Texas. Components such as these may be sources of gas leaks. Image credit: Roy Luck, Flickr.12
Leak Detection and Mitigation
In 2016, the EPA issued emissions standards aimed at reducing methane emissions from new sources or facilities by detecting leaks and repairing or replacing leaking equipment at oil and natural gas wells, processing plants, pipelines, gas compressors, and valves and connectors in these systems.14 As of 2018, the Administration, Congress, and the courts are involved in multiple ongoing actions to amend, advance, or delay the regulation.10,15
Some states, such as California16 and Pennsylvania,17 require operators to perform periodic leak detection surveys of oil and gas facilities, followed by mandatory repair or replacement if leaks are found.
Voluntary Emissions Reduction Programs
The EPA’s voluntary Natural Gas STAR certification program, which includes over 150 partnerships with oil and gas production, transmission, and distribution companies, encourages and documents the use of emissions-reducing technologies.18
Because methane emissions are also a major issue in agriculture, EPA’s AgSTAR program promotes the use of biogas recovery systems to capture methane emissions from livestock waste to be used as fuel.19
Bradbury, J. et al. (2013). Clearing the Air: Reducing Upstream Greenhouse Emissions from U.S. Natural Gas Systems. Working Paper. Washington, DC: World Resources Institute.
National Academies of Sciences, Engineering, and Medicine (2018). Improving Characterization of Anthropogenic Methane Emissions in the United States. Washington, DC: The National Academies Press.
1 U.S. Environmental Protection Agency – Natural Gas STAR Program: Overview of the Oil and Natural Gas Industry.
2 File:Flaring extra Gas in the Bakken.JPG. Wikimedia Commons user Joshua Doubek. Reproduced according to a CC BY-SA 3.0 license.
3 U.S. Environmental Protection Agency – Understanding Global Warming Potentials.
4 U.S. Environmental Protection Agency – Ozone Pollution.
5 American Petroleum Institute (2017). Natural Gas, Oil Industry Launch Environmental Partnership to Accelerate Reductions in Methane, VOCs. December, 2017.
6 U.S. Environmental Protection Agency – Controlling Air Pollution from the Oil and Natural Gas Industry: New Source Performance Standards and Permitting Requirements.
7 National Conference of State Legislatures (2014). State Methane Policies.
8 International Petroleum Industry Environmental Conservation Association (2014). Green Completions.
9 U.S. Environmental Protection Agency (2012). Overview of Final Amendments to Air Regulations for the Oil and Gas Industry.
10 U.S. Environmental Protection Agency – Actions and Notices about Oil and Natural Gas Air Pollution Standards.
11 U.S. Energy Information Administration (2016). Natural gas flaring in North Dakota has declined sharply since 2014. Today in Energy, June 13, 2016.
12 Roy Luck – Crosstex gas processing facility. Taken on May 9, 2009. Flickr. Reproduced according to a CC BY 2.0 license.
13 U.S. Bureau of Land Management (2016). Waste Prevention, Production Subject to Royalties, and Resource Conservation. Federal Register, 81, p. 83008-83089, November 18, 2016.
14 “EPA Releases First-Ever Standards to Cut Methane Emissions from the Oil and Gas Sector.” U.S. Environmental Protection Agency press release, May 12, 2016.
15 Clark Hill PLC (2017). Court Vacates EPA Stay of Methane Emissions Final Rule. Lexology, September 29, 2017.
16 California Air Resources Board (2017). CARB approves rule for monitoring and repairing methane leaks from oil and gas facilities. News Release #17-18, March 23, 2017.
17 Pennsylvania Department of Environmental Protection – How Pennsylvania is Regulating Methane from the Oil and Gas Industry.
18 U.S. Environmental Protection Agency – EPA’s Voluntary Methane Programs for the Oil and Natural Gas Industry.
19 U.S. Environmental Protection Agency – AgSTAR: Biogas Recovery in the Agricultural Sector.
Petroleum and the Environment
Download a full PDF of Petroleum and the Environment (free) or purchase a printed version ($19.99).
Other parts in this series:
1. Petroleum and the Environment: an Introduction
2. Water in the Oil and Gas Industry
3. Induced Seismicity from Oil and Gas Operations
4. Water Sources for Hydraulic Fracturing
5. Using Produced Water
6. Groundwater Protection in Oil and Gas Production
7. Abandoned Wells
8. What Determines the Location of a Well?
9. Land Use in the Oil and Gas Industry
10. The Pinedale Gas Field, Wyoming
11. Heavy Oil
12. Oil and Gas in the U.S. Arctic
13. Offshore Oil and Gas
14. Spills in Oil and Natural Gas Fields
15. Transportation of Oil, Gas, and Refined Products
16. Oil Refining and Gas Processing
17. Non-Fuel Products of Oil and Gas
18. Air Quality Impacts of Oil and Gas
19. Methane Emissions in the Oil and Gas Industry
20. Mitigating and Regulating Methane Emissions
21. Regulation of Oil and Gas Operations
22. Health and Safety in Oil and Gas Extraction
23. Subsurface Data in the Oil and Gas Industry
24. Geoscientists in Petroleum and the Environment
Glossary of Terms