An EnCana official has called on the U.S. Environmental Protection Agency (EPA) to withdraw its 2011 draft report on the evaluation of data from two monitoring wells at Encana's Pavilion natural gas field in Wyoming, saying the report data is inaccurate and that the data does not support the report's conclusions.
Instead, EPA's focus should shift from deep underground the Pavilion field and focus on the original issue at Pavilion – complaints by a few local landowners about specific palatability issues about water from their much shallower domestic wells, David Steward, team lead for Encana's environment, health and safety operations in Wyoming, told reporters in a conference call last week.
"The bottom line is that the EPA report and the U.S. Geological Survey (USGS) report provide no evidence that hydraulic fracturing has impacted groundwater resources in the Pavilion field," Steward noted.
Steward called EPA's response to a handful of documented complaints about domestic water well quality in Pavilion misguided. These complaints related to palatability, or taste and odor, only, Steward noted.
In its initial investigation, EPA should have considered data from existing reports on drinking water quality in the area. A USGS report dating from the 1950s documents the poor quality of groundwater near Pavilion, prior to any oil and gas development in the area, Steward said.
"Taste and odor problems, as documented by EPA itself, typically originate from sources such as sulfate, bacteria and dissolved solids," Steward noted. "Instead, EPA began by focusing on the natural gas industry through examination of methane (odorless, colorless, tasteless and non-toxic) and diesel range organics (DRO), ignoring the most likely causes."
Most of the domestic wells sampled for the investigation exceeded the palatability criteria for sulfate and total dissolved solids, including at least two of the residences with palatability complaints, Steward said.
"On the other hand, no oil and gas constituents exceeded drinking water standards in samples taken from domestic wells. However, many of them were high in sulfates and other naturally occurring compounds. This goes to the heart of our contention that EPA has focused its attention on the wrong thing," a company spokesperson said.
The DRO detections had a chemical fingerprint unrelated to naturally occurring fossil fuels such as condensate from gas wells, Steward noted. Methane is naturally occurring and levels were low.
"EPA has no basis for its early warnings about methane hazards."
"However, the implication is that drinking water could potentially be impacted. So rather than focus on specific complaints about the palatability of drinking water—taste, odor, appearance—EPA chose to focus on a theory that groundwater is broadly contaminated," a company spokesperson told Rigzone.
Additionally, EPA mischaracterized spatial considerations in the Pavilion field.
"Domestic wells are hundreds to thousands of feet shallower than the production wells, with largely impermeable shale in between. Domestic wells and production wells also target different depths in different geological zones or members," Steward commented.
Most water wells are about 300 feet deep. The two monitoring wells EPA installed in 2010 are 850 feet to 900 feet deep. EnCana's wells are 1,500 feet deep or greater, a company spokesperson said.
EPA also mischaracterized the groundwater flow, with horizontal flow generally moving south/southeast and away from the Town of Pavilion. In regard to vertical migration, EPA states that the direction of groundwater flow in Pavilion is "undefined" and then suggests an upward gradient.
"In fact, the data and literature overwhelmingly document a downward gradient in Pavilion and recharge from surface sources. So there's no migration pathway from deeper zones to the shallow zones where domestic wells are completed," Steward noted.
A third mischaracterization EPA made in the report was the field's geology. EPA noted that the Pavilion field is comprised mainly of porous sandstone lenses and a limited amount of low permeability shale. However, USGS reports confirm the field is comprised of 80 percent low permeability and 20 percent higher permeability sandstone lenses, the opposite of EPA's characterization.
"This distinction is important in understanding potential migration pathways," Steward noted. "Fluids don't readily migrate in this sort of system."
Steward also criticized EPA' placement of the monitoring wells in the center of a gas field at the interface of the shallower Lost Cabin geologic zone and the deeper Lysite zone.
"This accounts for the presence of hydrocarbons in the two wells," Steward said. "As we've said before, Encana didn't put hydrocarbons there, nature did."
Both wells were also designed and drilled too deep to evaluate environmental conditions at the much shallower depths where the domestic water wells are completed. The two wells are also more than a mile apart; no scientific basis exists for extrapolating or interpolating data between these two locations, Steward said.
EnCana also entered historic pits located near the field, which have been used for drill cuttings or drilling fluids, into a Voluntary Remediation Program managed by the state of Wyoming. The pits were utilized by companies that pre-date EnCana and were common practice at the time they were operating there. EnCana made the decision to enter the pits into the VRP after acquiring the field in 2004 and determining there was some limited groundwater contamination resulting from a few of the pits, an EnCana spokesperson said.
Steward said the impacts do not extend to or threaten any domestic wells and are not related to the palatability complaints.
"This is important because it's an indication than un-cemented zones on the backside of the production casing of these wells are not providing a migration pathway as theorized by the EPA," Steward commented.
EPA told Rigzone in a statement last week that the EPA has released new monitoring well data as part of the agency's ongoing analysis of groundwater quality in the Pavilion, Wyo., area. This data was collected in collaboration with the USGS, which conducted its own sampling at one of the wells.
EPA said the data that USGS released earlier this year and EPA's new data are "generally consistent" with the monitoring data including in EPA's December 2011 draft report on Pavilion Area Ground Water Investigation. The data, along with EPA's draft report and USGS data, will be submitted to an independent expert peer review panel. In October, EPA extended the public comment period on the Draft Report until Jan. 15, 2013 to give stakeholders sufficient time to consider all data related to the Pavilion, Wyo., groundwater investigation.
Officials with the American Petroleum institute in October criticized the EPA for its methods in gathering and analyzing data from the two monitoring wells.
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