The U.S. Environmental Protection Agency (EPA) released comments last week that were critical of the recent Wyoming Department of Environmental Quality (DEQ) draft report, which found hydraulic fracturing is “unlikely” the cause of water contamination in Pavillion, Wyoming.
It was an ironic twist, to say the least, considering it was the EPA that completely botched its 2011 Pavillion study. That draft study, which theorized fracking contaminated groundwater, was roundly criticized by state, federal and industry officials before being thoroughly disproven by subsequent testing. In response, the EPA — fearing its conclusions could not be supported in the face of increased scrutiny — withdrew its draft report from the peer-review process and turned the investigation over to state regulators.
Flash forward four years, and the EPA has issued an 18-page critique of the investigation it ended up handing over to state regulators in 2012. With regard to the process of fracking specifically, the EPA claims the Wyoming DEQ failed to provide sufficient evidence to support its conclusion that natural methane migration is the primary cause water well contamination. EPA also suggests DEQ’s assessment that fracturing fluids likely did not migrate from depth into water wells lacks supporting evidence:
“The Report generally concludes gas is present in the shallow Wind River formation as a result of natural upward migration from source rock (though acknowledging that some potential contribution may have come from movement up gas wellbores); that gas was widely present in the shallow subsurface prior to energy development; and that there is negligible likelihood that hydraulic fracturing fluids have migrated upward to depths utilized by water supply wells. All of these conclusions would benefit from additional support.”
In both instances, EPA is effectively asking the DEQ to prove a negative, which is impossible. Here’s a look at EPA’s two primary issues with the Wyoming DEQ report and why the DEQ’s conclusions are solid.
EPA CLAIM: “The Report concludes that hydraulic fracturing fluids had a “negligible likelihood” of reaching shallower zones used for drinking water. This conclusion relies primarily on the relatively small fracturing fluid volumes reportedly used in the field – ‘often less than 200 bbls.’ No data or reference is provided for the fracturing volumes. This conclusion lacks supporting data, and given the short vertical distances between water supply well depths and gas well fracture depths relative to other production areas across the country, may need qualification.”
FACT: The DEQ offers specific explanations as to why it is highly unlikely fracturing fluids could migrate vertically into aquifers despite shallow stimulation depths
The Wyoming DEQ report explains, “It is unlikely that hydraulic fracturing fluids have risen to shallower depths intercepted by water-supply wells. Evidence does not indicate that hydraulic fracturing fluids have risen to shallow depths intersected by water-supply wells.”
One reason the DEQ identifies is the fact that — despite fracturing treatments occurring at relatively shallow depths in the Pavillion area — typical volume of fracking fluids used during well stimulation treatments in the area are much less than what is typically used for high-volume, horizontal stimulations in shale plays in other areas of the country:
“… the small hydraulic fracturing fluid volumes employed in the Pavillion Gas Field make it unlikely for the fracture fluids to propagate a significant vertical distance. The typical treatment volumes reported for stimulating the occasional thin upper production zones between 1,400 and 2,000 ft bgs tend to be as small as 75 to 100 barrels of water.”
The DEQ report further elaborates on how Pavillion is far different than shale gas plays such as the Marcellus and Haynesville.
“The Pavillion Gas Field is different than gas fields recently associated with hydraulic fracturing in other areas, in that the gas is sourced from permeable sand reservoirs using standard vertical wells, and not sourced from less permeable shale using horizontally-drilled wells.”
According to Halliburton, between 1,000 and 10,000 gallons (24 and 238 barrels) of fracking fluid are used per well interval in the area, with 70 percent of the fluid made up of carbon dioxide foam. For perspective, consider that typically four million gallons of fracking fluid are used in high-volume fracking treatments in other parts of the country.
In Wyoming, the shallowest fracking stimulations occur at 1,400 feet, while the deepest water wells permitted in the state are 300 feet, due to the common knowledge that hydrocarbon-bearing, non-commercial shallow gas zones can be accessed at 500 feet (despite this well-understood fact, some water wells have been drilled as deep as 1,000 feet, however). With these facts in mind, the following DEQ calculations included in Appendix G of the report illustrate why it is physically implausible for fracturing fluid to migrate vertically hundreds of feet into aquifers:
“… the fracture created in the impermeable rock by a 100-barrel (4,200 gallon) stimulation may rise to a maximum of 30 ft above the top of the stimulation interval, assuming that all of the fluid remains in the fracture. When the stimulation volume doubles, with all other conditions unchanged, the fracture rise only increases by 26 percent. For example, in the Pavillion Gas Field, for a 1,000-barrel stimulation (including the volume of liquid CO2), the fracture rise may be a maximum of 65 ft. The 30 to 65 ft estimated height of fracture rise is much smaller than the several hundred feet separating the highest production interval from the shallow permeable zones that intersect the water-supply wells included in the 2014 Groundwater Investigation.”
Furthermore, the DEQ explains why – in addition to gravity – fracturing fluids do not easily travel vertically:
“… these producing horizons become pressure sinks (where pressure is low) as gas is withdrawn during production. Fluids, especially gas, cannot flow away from this zone because the fluids will encounter higher pressures moving outward.”
Not only did the DEQ not find evidence that fracking fluids have risen to “shallow depths intersected by water supply wells” (translation: fracking fluids were not detected in the 13 water wells included in the study), its illustration of fracking methods used in the region demonstrate exactly why this hasn’t occurred.
Which begs the question as to exactly what other supporting data the EPA would require DEQ to illustrate their assessment that fracking fluids could not reasonably reach aquifers is a valid one.
EPA CLAIM: “…. There is limited data to support the conclusion that gas was widely present in the shallow subsurface” prior to oil and gas development.
FACT: There is actually more than ample anecdotal and hard evidence that naturally occurring gas seepage – which can migrate as shallow as 500 feet – has contributed to poor water quality in the region for decades, a fact the Wyoming DEQ report explains:
“Evidence suggests that upward gas seepage (or gas charging of shallow sands) was happening naturally before gas well development… This upward migration occurs in part due to the lack of a thick regionally extensive impervious stratum in the Pavillion Gas Field area such as the Waltman Shale (Johnson and Rice, 1993; USGS, 1996). This lack of a regional “seal” makes the Pavillion Gas Field unique – the gas is only trapped by the shale, siltstone, and claystone that surround the permeable lenses of sandstone.”
The 1996 USGS report referenced also states, according to the DEQ, “where the lacustrine shale is absent, such as in the Pavillion Gas Field, gases produced from the overlying Wind River Formation are similar to those produced from deeper formations, and thus, probably migrated vertically upward from deeper source rocks.”
DEQ also references a 1951 United States Bureau of Reclamation (USBR) report in which it found:
“Gas was reported in a water-supply well in the Pavillion area pre-dating the start of oil and gas development in 1960. During the drilling of a water-supply well in March 1951 (“Camp 9” well), a satisfactory water producing zone was encountered at a depth of 500 ft, but the well was plugged back due to the presence of gas in the water. This “Camp 9” well was located in the NW ¼ of NW ¼ of T4N R3E Section 32, which is adjacent to the northeast corner of the Pavillion Gas Field and the Study Area (USBR, 1951). According to well permit records, the final completion depth of the “Camp 9” well was 300 ft bgs (WSEO, May 11, 2015).”
EPA contends this was 2.5 miles away from nearest well that was in study and there was no indication that it was methane. But considering the similar geography of an area merely hundreds of feet away from the current site of the Pavillion gas fields — and that methane is the chief component of natural gas — it would seem highly plausible such shallow methane could be encountered anywhere in the general region.
DEQ also points to data from a review of open-hole geophysical logs obtained from the WOGCC site for wells drilled between 1965 and 1973 indicating, “the presence of gas-filled porosity at approximately 650, 682, and 827 ft bgs. This suggests the presence of natural gas in groundwater at depths used for domestic water supply prior to extensive commercial development in the Pavillion Gas Field.”
EPA counters it “was able to locate and review ten mud logs from wells drilled before 1995” (the mid 70s to early 80s, according to its 2011 draft report) and found they “did not indicate gas shows within 300 meters of the surface.” Although the latter may be true, EPA’s counter-argument does not negate the evidence DEQ lists for wells between 1965 and 1973 of shallow gas referred to in the DEQ report.
In addition to the examples listed in the DEQ report, the following sources confirm DEQ’s assertion that gas migration of gas by natural means pre-dates natural gas production in the area:
- A 1991 USGS report found: “Dissolved-solids concentrations in all water samples … were 2 to 14 times greater than the Secondary Maximum Contaminant Level of 500 mg/L set by the EPA.” (pg. 103).
- A 1989 USGS report found: “The ground water in Fremont County was ranked the fourth most vulnerable to pesticide contamination in Wyoming. … Six of the 18 focal pesticides and 1 non-focal pesticide were detected in Fremont County. At least one pesticide was detected in 13 of the 20 wells sampled in Fremont County.
- A 1992 USGS Report found: water quality “is variable in the Wind River Formation because this unit has highly variable lithology, permeability, and recharge conditions.”
- And the DEQ website explains: “Methane (CH4) is a naturally occurring hydrocarbon gas found underground. It is present in shallow and deep coal beds as well as other rock units, and is the main hydrocarbon found in natural gas, or coal bed gas. Methane can occur dissolved in the groundwater or as a gas in the soil and rock zones below the surface. Methane migrates from areas of high pressure to areas of low pressure. Mining and well drilling operations can affect the pressure in the subsurface and cause the migration of methane to areas of lower pressure such as shallow aquifers, and water wells used as water supplies. Gas migration in the subsurface can also be influenced by an increase or decrease in the water level of an aquifer. Active water well pumping, cessation of irrigation or underground mining operations can lower groundwater levels, reducing pressure in aquifers occurring above and adjacent to the area of coal extraction. This reduction in pressure can allow gases within the overlying rock layers to migrate into nearby water wells.”
Natural migration of methane is quite common throughout the country, and as the DEQ report illustrates, it’s a common phenomenon in Wyoming as well.
The EPA offering a critique a Pavillion water study is more than a little ironic, considering the nearly universal backlash the EPA received for the faulty methods used in its 2011 study.
First of all, EPA used the results from two monitoring wells drilled at depths of 981 and 783 feet, respectively. Wyoming water wells are restricted at 300 feet or less for a reason, due to the well known fact that drilling deeper could result in striking one of the area’s shallow hydrocarbon deposits. So it’s no surprise that the EPA’s samples detected hydrocarbons in those monitoring wells. The DEQ also used “downhole camera” investigation to expose the fact that EPA used carbon steel casing rather than stainless steel on the wells, as it had claimed. The USGS also effectively disqualified one of the wells due to low flow rates and poor construction. Both of these factors could have introduced contaminants. When the U.S Geological Survey (USGS) conducted its own subsequent testing, they had more than 50 separate measurements that differed from EPA’s results.
Oddly, the exact data from those two wells were regurgitated last week in a Stanford study trumpeting that it “for the first time, demonstrated impact to Underground Sources of Drinking Water (USDWs) as a result of hydraulic fracturing.” It should come as no surprise that one of the lead researchers of that report, Dominic DiGuilio, was also one of the authors of the EPA’s Pavillion study.
Another member of the Stanford research team, Dr. Rob Jackson, was one of the Duke University researchers who published studies in 2010 and 2013, which also claimed fracking could have contaminated groundwater. Those reports suffered from a number of major flaws, several and numerous studies by USGS, Syracuse University and other reputable research organizations, have thoroughly debunked those claims.
The DEQ report does not deny that oil and gas activity, such as seepage from exceedingly rare faulty well casings and surface spills can lead to water contamination, but the DEQ determined contamination in Pavillion is likely attributable to migration of methane that occurred naturally, and they found no evidence that the hydraulic fracturing process was to blame. The report also clearly illustrates the fact that gas can and has naturally migrated into water sources in the past.
EPA’s skepticism of these conclusions reads more like a desperate attempt to save face in the wake of its past faulty methods in Pavillion rather than an objective critique of the report.