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Routine flaring

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Night view from above west Texas looking southeast across the Gulf Coast region of the U.S. (left) and Mexico (right). The broad arc of scattered lights extending up and left from the lower center is defined by hundreds of gas flares from rural oil wells in the Eagle Ford Group south of San Antonio. Note also the visible boundary of earth's atmosphere. Image taken from International Space Station, February 2015.

Routine flaring, also known as Production flaring, is a method and current practice of disposing of large unwanted amounts of associated petroleum gas (APG) during crude oil extraction. The gas is first separated from the liquids and solids downstream of the wellhead, then released into a flare stack and combusted into earth's atmosphere; usually in an open diffusion flame. Where performed, the unwanted gas (mostly natural gas dominated by methane) has been deemed unprofitable, and may be referred to as stranded gas, flare gas, or simply as "waste gas". Routine flaring is not to be confused with safety flaring, maintenance flaring, or other flaring practices characterized by shorter durations or smaller volumes of gas disposal.[1]: 1 [2]

145 billion cubic meters (over 5 trillion cubic feet) of natural gas is estimated to have been flared worldwide during 2018.[3] The majority of this was routinely flared APG at thousands of well sites, and is a waste amount equal to the natural gas usage of South and Central America. The largest seven practitioners since 2014 are Russia, Iraq, Iran, the United States, Algeria, Venezuela and Nigeria.[4] Activity in remote regions of Russia is greatest, with political conflict elevating the levels in other countries. The U.S. contributed nearly 10% of the 2018 world total.[5]

Global gas flaring and oil production trends (1996-2018)
  Gas flared: Billion Cubic Meters/Year (↓10%)
  Oil produced: Million Barrels/Day (↑40%)
  Population: 100 Million People (↑30%)
Based on data provided by the World Bank, June 2019 [6]

Routine flaring, along with intentional gas venting and unintentional fugitive gas emissions, have profound negative consequences. The wasting of a primary resource provides no present economic or future wealth benefits, while creating liabilities through the build up of greenhouse gases and other harmful pollutants in the biosphere.[7][8] With most forecasts showing oil and gas use increasing into the foreseeable future, the World Bank in 2002 launched the international Global Gas Flaring Reduction Partnership (GGFRP); a public-private partnership with the aim of retiring the wasteful practice.[9] In 2015, it further launched the Zero Routine Flaring by 2030 Initiative; endorsed by 32 countries, 37 companies, and 15 banking institutions by the end of 2019.[10] Endorsers based in the U.S. were the U.S. Federal Government, the State of California, and the World Bank. Global data spanning 1996-2018 indicate that flared gas volumes fell 10%, while oil production rose 40%.[6]

Causes

Expansion of flaring activity in Permian Basin of west Texas from 2012 to 2016. VIIRS images from NASA Earth Observatory

The routine flaring and venting of APG has been practiced since the first oil wells were commercialized in the late 1850's. Although liquid and gas hydrocarbons have similar energy densities by mass, the factor of 1000 greater energy content by volume of liquid fuels makes storage and transport more economical.[11] Widespread means for overcoming this relative disadvantage of petroleum gas have only been realized within the last several decades. For example, transcontinental gas pipelines, linked with regional collection and distribution networks, now spread throughout much of the world.[12] Flare Gas Recovery Systems (FGRS) for processing APG into liquid or compressed fuels at the wellpad have also become increasingly mobile and varied in their capabilities.[1]: 50 

The decision processes leading to wasting of APG in modern times depend greatly upon regional circumstances. Generally, the near-term financial and risk management objectives of decision makers will determine the outcome. Some form of permitting or other regulation of flaring and venting activity exists in most jurisdictions, but details vary widely.[1]: 20 [13]: 7  Factors that can increase wasting activity include (not a complete list):

  • rapidly expanding oil extraction into regions farther remote from the existing gas pipeline infrastructure.[1]: 49 
  • increased challenges in logistics, such as delays in expansions of transport capacity.[14]
  • oversupply of natural gas leading to low or negative producer prices.[15]
  • competition from lower cost and lesser contaminated sources of natural gas.[16]
  • more transitory (both temporal and geographical) nature of some oil extraction operations (e.g. tight shale oil).[8]
  • lack of on-site alternatives with sufficient agility for integration with differing operations and schedules.[1]: 55 
  • weak regulation, as caused by political conflict or instability.[3]

Alternatives

Routine flaring (image center) at a crude oil extraction site in North Dakota. It is one among thousands of similar sites in the United States and throughout the world.

Similar to crude oil, APG is a primary energy source of both gaseous fuel and liquid fuel commodities that have high intrinsic value in the modern world economy.[17] After APG is extracted, the remaining logistical barriers to consumption are cost-effective refinement and delivery to consumer markets. Flaring alternatives preferred by the oil companies include those which remove these barriers for associated gas without impeding production of higher value oil.[1]: 55 

Traditional

1. transmission to a trading hub for distribution to short-term storage and refinery markets (preferred).
2. re-injection for enhanced oil recovery and/or longer-term storage.[18]: 542 

Novel

The following list includes existing commercially viable alternatives that can be performed on-site or nearby:

1. liquid fuels production with Flare Gas Recovery Systems (FGRS) and trucking to consumption markets.[18]: 542 [1]: 50 
a. natural gas liquid (NGL) extraction from the flare stream using mobile equipment.
b. portable compressed natural gas (CNG) production.
c. portable liquefied natural gas (LNG) production.
d. small-scale gas to liquids (GTL) conversion.
2. electricity generation with portable engines or microturbines.[18]: 548 [1]: 51 
3. heat generation for water treatment or other industrial processing at the wellpad.[1]: 52 

A 2019 report from the U.S. Department of Energy states a likely reason oil companies may be slow to embrace either existing or advanced FGRS technologies is "legal, regulated flaring is the least risky option and does not require learning how to apply new technologies or modifying existing contracts and operating practices." [1]: 55 

Effectiveness

Gas flares using diffusion flames depend primarily on thorough air-gas mixing throughout the ejected gas stream to achieve complete combustion. The velocity and pressure drop of the gas as it exits the tip of the flare stack must be maintained within optimal ranges to ensure adequate turbulent diffusion. Preserving these ranges are key objectives of the engineering design process and accompanying control strategy. Significant amounts of moisture, nitrogen, carbon dioxide, or other non-hydrocarbons accompanying APG can interfere with combustion. On the other hand, properly designed and controlled injections of hot air and steam can improve combustion and effectiveness.[19][20]

APG consists primarily of methane along with lesser amounts of ethane, propane, butane, and other alkanes. When a flare is operating effectively, the combustion by-products include primarily water and carbon dioxide, and perhaps small amounts of carbon monoxide and nitrous oxides (NoX). Such flares thus demonstrate nearly complete combustion and a high conversion efficiency. When a flare is not operating effectively, substantial amounts of APG can escape. Also volatile organic compounds (VOCs), toxic compounds, and other damaging pollutants can be created. VOCs and NoX can act to produce ground-level ozone at levels that exceed air quality standards. The presence of smoke indicates a poorly operating flare.[18]: 534–537 

Most other contaminants in the APG stream occur as trace amounts. They can include toxic elements like mercury and radon that are naturally occurring. Enhanced oil recovery efforts such as hydraulic fracturing may introduce others. The common natural contaminant hydrogen sulfide enables the creation of sulfur dioxide and sulfuric acid in gas flares.[21] At elevated concentrations, it can cause corrosion and other air quality challenges, and result in characterizations such as "sour gas" and "acid flare". As a practical matter, gas streams with higher sulfur contamination levels are more likely to be flared - where allowed - than utilized due to their lower economic value.[16]

Growth in the United States

Historical chart of the volumes of gas extracted, flared and vented in the United States. Data from U.S. Energy Information Administration

Reported flaring and venting in the U.S. declined in the decades following World War 2, based on data from the U.S. Energy Information Administration.[5] Near the end of the 20th century, it reached lows close to 1.5% of APG extracted, and 0.5% of all gas extracted from both oil and gas wells. Since about 2005, the activity has returned to a growth path, as shown in the accompanying charts.

32 states host and regulate gas flaring and/or venting.[22] The largest volume changes since about 1990 have been in the Permian Basin of west Texas and New Mexico, the Bakken Formation of North Dakota, and the Eagle Ford Group of southeast Texas.[23]

Historical chart of the percentages of gas flared and vented in the United States.

The U.S. activity increase exists in both volume and percentage terms. In 2018, it recaptured nearly 50-year highs, with 500 billion cubic feet and 7.5% of APG being flared. Reports of negative producer prices for natural gas, and of a further doubling of activity in the Permian, indicate the growth trend continued in 2019.[15][24] In 2018-2019, the amount of gas wasted daily in the Permian alone was capable of supplying the residential needs of the entire state of Texas.[25] Five new long-distance gas pipelines from the region are under construction, with the first entering service in Q3 2019,[26] and the others scheduled to come online during 2020-2022.[1]: 23 

A loosening in U.S. federal regulatory policy starting 2017 enabled further increases to the waste of APG from both public and private lands.[1]: 17–19  These are summarized in a June 2019 report from the U.S. Department of Energy, which identifies the most consequential changes as:[1]: 17 

1) "the rollback of the ... limits on methane leaked, vented, or flared from oil and gas wells on federal lands"; and
2) "removing the requirement that companies seek out and repair leaks, requirements for reducing emissions from a variety or equipment elements, and requirements that companies prepare plans for minimizing waste before getting drilling permits"

See also

References

  1. ^ a b c d e f g h i j k l m "Natural Gas Flaring and Venting: State and Federal Regulatory Overview, Trends, and Impacts" (PDF). U.S. Department of Energy. 2019-06-01. Retrieved 2019-12-29.
  2. ^ "IPIECA - Resources - Flaring Classification". International Petroleum Industry Environmental Conservation Association (IPIECA). Retrieved 2019-12-29.
  3. ^ a b "Increased Shale Oil Production and Political Conflict Contribute to Increase in Global Gas Flaring". World Bank. 2019-06-12.
  4. ^ "Top 30 Flaring Countries (2014 –2018)" (PDF). World Bank. June 2019.
  5. ^ a b "Natural Gas Gross Withdrawals and Production Data". U.S. Energy Information Administration. Retrieved 2019-12-28.
  6. ^ a b "Global gas flaring and oil production (1996-2018)" (PDF). World Bank. June 2019.
  7. ^ "Global Gas Flaring Reduction Partnership". World Bank. Retrieved 2019-12-29.
  8. ^ a b Zoheir Ebrahim and Jörg Friedrichs (2013-09-03). "Gas flaring - the burning issue". resilience.org. Retrieved 2019-12-29.
  9. ^ "Global Gas Flaring Reduction Partnership". United Nations. Retrieved 2019-12-29.
  10. ^ "UN Climate Initiatives Platform - Zero Routine Flaring by 2030". United Nations. Retrieved 2019-12-29.
  11. ^ "Fuel energy density". University of Calgary. Retrieved 2019-12-29.
  12. ^ "Global natural gas pipeline network". snam. Retrieved 2019-12-29.
  13. ^ "Regulation of Associate Gas Flaring and Venting: A Global Overview and Lessons from International Experience" (PDF). World Bank. 2004-02-01. Retrieved 2019-12-31.
  14. ^ "US natgas 2020-21 winter futures rise after Kinder delays Permian pipe". Reuters. 2019-09-17. Retrieved 2019-12-31.
  15. ^ a b Scott DiSavino (2019-05-22). "U.S. natural gas prices turn negative in Texas Permian shale again". Reuters. Retrieved 2019-12-31.
  16. ^ a b "Natural gas and the environment". U.S. Energy Information Administration. Retrieved 2019-12-29.
  17. ^ "Natural gas explained". U.S. Energy Information Administration. Retrieved 2019-12-29.
  18. ^ a b c d Emam, Eman A. (2015). "Gas Flaring in Industry: An Overview" (PDF). Petroleum and Coal. 57 (5): 532–555.
  19. ^ John Sorrels, Jeff Coburn, Kevin Bradley, and David Randall (2019-08-01). "EPA - VOC Destruction Controls - Flares" (PDF). U.S. Environmental Protection Agency. Retrieved 2019-12-31.{{cite web}}: CS1 maint: multiple names: authors list (link)
  20. ^ "EPA enforcement targets flaring efficiency violations" (PDF). U.S. Environmental Protection Agency. 2012-08-01. Retrieved 2019-12-31.
  21. ^ "Frequent, routine flaring may cause excessive, uncontrolled sulfur dioxide releases" (PDF). U.S. Environmental Protection Agency. 2000-10-01. Retrieved 2019-12-31.
  22. ^ "Fact Sheets: Natural Gas Flaring and Venting Regulations by State". USDOE Office of Fossil Energy. Retrieved 2020-01-05.
  23. ^ "Natural gas venting and flaring increased in North Dakota and Texas in 2018". U.S. Energy Information Administration. 2019-12-06. Retrieved 2019-12-31.
  24. ^ Nick Cunningham (2019-12-14). "Emissions Soar As Permian Flaring Frenzy Breaks New Records". Oilprice.com. Retrieved 2019-12-31.
  25. ^ Kevin Crowley and Ryan Collins (2019-04-10). "Oil Producers Are Burning Enough 'Waste' Gas to Power Every Home in Texas". Bloomberg News. Retrieved 2019-12-31.
  26. ^ "Gulf Coast Express Pipeline placed in service ahead of schedule". Business Wire. 2019-09-24. Retrieved 2019-12-31.
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