Fracking for Natural Gas
Enhancing Natural Gas Production from Buried Rock
The business of hydraulic fracturing (aka fracing or fracking) to entice natural gas (mostly methane) out of hard rocks is on the minds of many rural citizens across the country. It especially concerns water well owners and their neighbors who signed lease agreements to gas producers and now face pollution of their drinking water.
The fracking process releases gas disseminated through rocks of low permeability (“tight formations,” such as shales) by injecting fluids into the gas-bearing formations at high pressure to induce fracturing. The induced fractures provide pathways for much easier collection of the gas for pumping to the surface. The injected fluids are laced with a large variety of chemicals,1 some carcinogenic. The high potential for contamination of water supplies by these dangerous chemicals, and even by the methane itself, is the chief public concern.2
As the craving for additional gas supplies increases, the potential scope of the problems from fracking spread to communities near gas-bearing coal beds, to regionally extensive shale formations. Figure 1 shows the huge extent of these areas in the lower 48 states.
The Safe Drinking Water Act of 1974 (SDWA) is the main regulation that protects drinking water supplies from wastes and other substances injected into the ground.3 SDWA allows a state to become the prime regulator of waste disposal and other activities under the Act. Thus, the U.S. granted the State of Alabama regulatory authority over that state’s production of natural gas from coal beds.
In 1995, an environmental group petitioned the U.S. Environmental Protection Agency (EPA) to withdraw approval of Alabama’s SDWA regulations because they did not cover hydraulic fracturing practices for enhancing coalbed gas production. The court denied that petition on grounds that hydraulic fracturing was part of the production process and thus exempt from SDWA. On appeal, the 11th Federal Circuit Court ruled in 1997 that hydraulic fracturing should be regulated under the SDWA.
Alabama revised its regulations in 1999, under EPA direction, but EPA’s approval was again appealed to the 11th Circuit Court, which in this case ruled (2001) that Alabama’s regulations comply with the SDWA. Subsequent federal legislation through 2003 has attempted, but failed, to exempt hydraulic fracturing from SDWA altogether.
In June 2004 EPA released a study of coal bed fracking for natural gas production, concluding that hydraulic fracturing fluids posed little or no threat to U.S. drinking water (USDW). EPA’s conclusion was based on a literature review and an array of untested assumptions, including the assumption that the fracturing process would dewater the coal beds and so dilute the fracturing fluids,4 and that processes of dispersion, adsorption, and potential biodegradation of contaminants in the water would eliminate any significant risk. These conclusions were unsupported by any research done by the EPA, and were severely criticized by two EPA employees in a private letter to three Congressmen.6 At the same time, the EPA obtained a Memorandum of Understanding from three major coalbed methane producers that they would stop using diesel fuel in fracking fluids – the only component considered potentially harmful by the EPA.5
The EPA study had serious flaws, because it only dealt with coal beds as methane reservoir rocks, and interpreted the lack of evidence for contamination of water supplies by hydraulic fracturing in some incidents as evidence for the absence of contamination from fracking processes. In addition, the 2004 EPA review focused entirely on threats to water supplies from the hydraulic fracturing fluids.
Hydraulic fracturing is applied to a wide variety of rock types, not all of which respond in the same way as coal beds. And the lack of evidence for contamination also lacked rigorous testing to assess the possibility of hydraulic fracturing causing drinking water pollution, not a simple matter. In addition to fracking fluids, the natural gas (and oil) sought by hydraulic fracturing, pollutants in the pore waters of oil and gas reservoir rocks , and pollutants entrained or adsorbed in migrating natural gas and hydraulic fracturing fluids by reaction with rocks through which they pass, all are potential sources of contamination. In the first case, combustion of methane in kitchen tap water7 (Figure 2) certainly suggests that methane released by hydraulic fracturing can and does migrate into water supplies.
By 2008, rapid escalation of shale gas exploitation in the east and south re-energized the issue of drinking water contamination from hydraulic fracturing, making it a news item and focus of increased citizen concerns. In 2009, companion House and Senate bills were introduced to eliminate the SDWA hydraulic fracture exemption. These bills also could require disclosure of proprietary fracking fluids’ chemical formulas to emergency personnel. Early in 2010 the National Association of Utility Commissioners requested that EPA
“…carry out a study on the relationship between hydraulic fracturing and drinking water, using a credible approach that relies on the best available science, as well as independent sources of information. The conferees expect the study to be conducted through a transparent, peer-reviewed process with other Federal agencies as well as appropriate State and interstate regulatory agencies in carrying out the study.”
This EPA study is underway.
Not surprisingly, oil and gas industry sources have been quick to loudly proclaim there is no proven connection between hydraulic fracturing8 and drinking water contamination, and that the industry is thoroughly regulated by the States. It’s simple to avoid finding casual connection between fracking and water supply contamination when no study is undertaken to assess the issue. The lack of studies so far is due in part to the industry’s unwillingness to look for connections, and also to the difficulty and expense of rigorous studies to prove the presence or absence of connections.
Diagrams that illustrate fracking show a branching network of connected fractures in a thin, underground layer, where the gas and fluids are confined. But these are no more than industry admen fantasies: the actual effects of fluids pumped into the ground at high pressure are quite poorly understood. The earth’s outer zones (crust) are a patchwork of vastly different materials that can respond to increased fluid pressures in markedly different ways. As a result, the extent and direction of induced fractures can be quite different from the ones envisioned.
For example, fractures may be controlled by pre-existing weaknesses in the rocks, providing pathways for fluid movement beyond target zones. The closer the target zones are to drinking water reservoirs (aquifers), the greater the risk of contamination. So even though the connection between fracking and observed water pollution near hydraulic fracking operations is still unproved by scientific studies, the widespread anecdotal evidence of changes in the character and abundance of well water closely associated with fracking strongly suggest a connection.
Credible numbers on the recovery of hydraulic fracture fluids are few and hard to find. Estimates range from 10% to 20% for “horizontal” drilling (the most common technique for exploiting tight formations)9 to “near-100%” from some industry sources. The amount of water—on the order of 5 million gallons per well,10 or more if more than one hydraulic fracturing event is required—is itself a controversial use of fresh water, because it ends up contaminated. Industry assumes that unrecovered fluids remain in the gas-bearing rock unit. But it is possible, if not likely, that contaminated water escapes to surrounding rocks along pathways created or enhanced by the fracking. The potential for contaminating drinkwater aquifers depends on the pathways opened and proximity to the gas-bearing formations.
Recovering fracking-contaminated water from very deep rock formations presents worse problems of disposal, even though deep rocks may be less likely to leak hydraulic fracturing fluids into drinking water aquifers. The fluids are pumped to lined surface holding ponds, which are vulnerable to leakage, overflow, and rupture. Any release may lead to contamination of surface waters and shallow drinking water aquifers.11 Eventually the fluids in holding ponds are removed for disposal, but protocols are not standard, and on western public lands, such contaminated waters commonly are dumped into evaporation ponds and surface streams,12 both of which may lead to groundwater contamination.
The as yet unresolved issues of fracking for natural gas supplies include: why is it necessary to produce methane from deep, tight formations? The short answer is that the U.S. gas industry is not finding shallow, porous, easily productive gas fields any more. Much of the nation’s methane resource was “flared,” (burned) at wells and refineries throughout the terminating “Oil Age,” and like North American petroleum production, only the difficult-to-exploit, and environmentally damaging gas deposits remain. So we’re destroying a precious life-giving resource, clean water, to grub out the last gasps of gas.13
1. 258 chemicals constituents of hydraulic fracturing fluids are listed in Table 5-6, Draft Supplemental Generic Environmental Impact Statement, Natural Gas Drilling, New York State Department of Environmental Conservation, October 1, 2009
2. The documentary film Gasland, by Josh Fox reveals the problems of water well contamination http://www.hbo.com/html/error/browser_message_c.html?return=http://www.hbo.com/documentaries?cmpid=ABC449; see also Judi Buehrer, Fracking Advocates, Opponents Speak Out, American Water Works Association, Streamlines, 2 (19): 2010
3. Stephen F. Heare, Hydraulic Fracturing: Regulatory and Policy Considerations, National Association of Regulatory Utility Commissioners, February 15, 2010,
http://www.narucmeetings.org/Presentations/Steve%20Heare%20EPA.pdf; S. Marvin Rogers, History of Litigation Concerning Hydraulic Fracturing to Produce Coalbed Methane, State Oil and Gas Board of Alabama, January 2009. http://www.iogcc.state.ok.us/Websites/iogcc/Images/Marvin%20Rogers%20Paper%20of%20History%20of%20LEAF%20Case%20Jan.%202009.pdf
4. Since the waters trapped in coal beds at formation are highly contaminated, this argument has little merit.
5. Weston Wilson, EPA Findings on Hydraulic Fracturing Deemed Unsupportable, Letter from geologist Weston Wilson, EPA employee, to Congresspersons Wayne Alard, Ben Nighthorse Campbell, and dated October 8, 2004, Diana DeGette, critical of the 2004 EPA report. http://www.ucsusa.org/scientific_integrity/abuses_of_science/oil-extraction.html
6. U.S. EPA, Study to Evaluate the Impacts to USDWs [U.S. drinking water supplies] by Hydraulic Fracturing of Coalbed Methane Reservoirs, Fact sheet EPA 816-F-04-017, June 2004. The Memorandum of Understanding, applies only to coalbed methane extraction, not to shale gas. http://www.epa.gov/safewater/uic/wells_coalbedmethanestudy.html
7. Josh Fox, Gasland. http://www.nytimes.com/2010/06/21/arts/television/21gasland.html
8. For example, Energy in Depth, Debunking GasLand, 9 June 2010. http://www.energyindepth.org/tag/gasland/
9. Ali Daneshy, Why Care About Treatment Fluid Recovery, E&P Magazine 2 June 2010. http://www.epmag.com/Magazine/2010/6/item60863.php
10. Chesapeake Energy, Water Use in Deep Shale Gas Exploration, March 2010. http://www.chk.com/Media/CorpMediaKits/Water_Use_Fact_Sheet.pdf
11. Jennifer Goldman, Earthworks, Hydraulic Fracturing Myths and Facts; Why Natural Gas Is Not the Answer, un-naturalgas.org, 11 June 2010. http://un-naturalgas.org/hydraulic_fracturing_a-z.htm. In the pond lining business, two types of liners are recognized: those that are leaking and those that will leak
12. Howard G. Wilshire, Jane E. Nielson, and Richard W. Hazlett, The American West At Risk: Science, Myths, and Politics of Land Abuse and Recovery (New York, Oxford University Press, 2008), p. 323-326. Disposal of coalbed methane waste waters in evaporation ponds in Wyoming and Montana resulted in unexpected hot spots of West Nile virus due to breeding of mosquitos in the shallow warm ponds
13. Shale gas is a significant contribution to North American gas supplies, but probably is much less than hyped in the media. As production expands, the reality diminishes because the core areas of really good production are turning out to be a small percentage of the total deposits (<10%). Technically recoverable shale gas is on the order of 150 trillion cubic feet (Tcf), about 7 years of current consumption. Twice that is recoverable from more conventional sources, but in all we are not looking at 100 years of supply as claimed. (Geologist Berman: Shale Gas Reserves ‘Substantially Overstated’, Interview, Association for the Study of Peak Oil-USA, 19 July 2010; reproduced by The Energy Bulletin. http://www.energybulletin.net)