Encana Oil & Gas (USA) Inc., a subsidiary of Encana Corporation, says it strongly disagrees with the US Environmental Protection Agency’s (EPA) preliminary conclusions on fracking in its draft report related to the groundwater study in the Pavillion natural gas field of Wyoming. (Earlier post.) Encana, the operator of the field, said it was “especially disappointed” that the EPA released the draft report, which outlined preliminary findings, before subjecting it to “qualified, third-party, scientific verification”.
On 9 December, EPA released a draft analysis of data from its Pavillion, Wyoming ground water investigation, indicating that ground water in the aquifer contains compounds likely associated with gas production practices, including hydraulic fracturing. In its study, EPA re-tested private and public drinking water wells in the community and drilled two independent deep monitoring wells.
EPA said that its samples were consistent with chemicals identified in earlier EPA results released in 2010 and are generally below established health and safety standards. EPA said it was releasing the findings for public comment and would submit them to an independent scientific review panel.
Encana said that the EPA data from existing domestic water wells aligned with all previous testing done by Encana in the area and showed no impacts from oil and gas development. The company also charged that many of the EPA’s findings from the recent deep monitoring wells, including those related to any potential connection between hydraulic fracturing and Pavillion groundwater quality, were conjecture.
Encana charged that numerous discrepancies exist in the EPA’s approach, data and analysis, and detailed a few:
Encana said that the EPA report ignores the Pavillion field’s unique geology and hydrology. As far back as the 1880s, US Geological Survey (USGS) reported poor water quality in Pavillion. More recent USGS reports dating back to 1959 documented Pavillion water as unsatisfactory for domestic use due to high concentrations of naturally occurring sulfate, total dissolved solids and pH levels which commonly exceed state and federal drinking water standards.
Pavillion is a shallow natural gas field, in which naturally occurring methane exists throughout the subsurface geology, filling channel sands. Encana said that this natural gas is “commonly known” to have been present in groundwater from domestic wells for decades, dating back to well before any natural gas drilling started.
Pavillion is unusual in that commercial natural gas is present at depths as shallow as 1,100 feet because there is no cap rock forming a barrier between the deeper natural gas and shallow intervals. Therefore, over the geologic ages, deeper natural gas has moved upward to shallower depths, according to the company. The natural accumulations of gas and water are in discontinuous (unconnected) sand pockets. At the same time, this geology does not allow water to move from one area to another because the discontinuous sand pockets are not regionally connected. Therefore, this area does not have a large continuous aquifer.
The EPA drilled two deep monitoring wells into a natural gas reservoir and found components of natural gas—an entirely expected result, Encana said. The results in the EPA deep wells are radically different than those in the domestic water wells (typically less than 300 feet deep), thereby showing no connection, according to the company.
Encana charged that there is unacceptable inconsistency between EPA labs’ analysis for numerous organic compounds reported to have been found in the EPA deep monitoring wells. Data is not repeatable and the sample sets used to develop these preliminary opinions are inadequate, according to the company.
Several of the man-made chemicals detected in the EPA deep wells have never been detected in any of the other wells sampled, according to Encana. They were, however, detected in many of the quality control (blank) samples—which are ultra purified water samples commonly used in testing to ensure no contamination from field sampling procedures. These two observations suggest a more likely connection to what it found is due to the problems associated with EPA methodology in the drilling and sampling of these two wells, according to Encana.
The EPA’s reported results of all four phases of its domestic water well tests do not exceed federal or state drinking water quality standards for any constituent related to oil and gas development.
Encana backgrounder on Pavillion. Pavillion is a farming and ranching community located in Fremont County, Wyoming with a population of about 175 residents. Drilling natural gas wells began in the Pavillion area in 1960. Encana acquired the Pavillion asset through a corporate acquisition of Tom Brown, Inc. in 2004. From 2004 to 2007 Encana drilled 44 wells. After drilling its last Pavillion well in 2007, Encana has not invested in growing production from this mature field where about 125 wells currently produce about 10 million cubic feet of natural gas per day—less than 0.3% of Encana’s daily production.
In 2005 a local resident complained of issues regarding the quality of the drinking water in Pavillion. Encana conducted seven rounds of tests between 2005 and 2007. The company says it sought the expertise of independent laboratories and the Wyoming Department of Environmental Quality (WDEQ).
When the EPA began conducting investigations in 2008, Encana worked with the agency and in 2010 became part of a voluntary working group with the WDEQ, the Wyoming Oil and Gas Conservation Commission (WOGCC), Wyoming Geologic Survey (WGS), Wyoming State Engineer’s Office (SEO) and the federal Bureau of Land Management.