Natural gas wells in the Pavillion Gas Field were properly drilled and maintained, but more study is needed to prove if energy operations contaminated drinking water wells in the region, according to a draft report released by Wyoming regulators today.
Those findings were among the conclusions of a draft report released by the Wyoming Oil and Gas Conservation Commission today. The report is one of three Wyoming is conducting investigating polluted drinking water near the town of Pavillion.
The source of that contamination has long been the subject of fierce debate. Environmentalists argue the industry practice of hydraulic fracturing, or fracking, was the cause. Industry representatives contend the pollution occurs naturally.
The U.S. Environmental Protection Agency initially and tentatively reported natural gas operations in the region were the cause of nearby polluted well water, but later backed away from that claim.
The state’s draft report on well integrity offered no firm conclusions.
It concluded “all wells were properly permitted, drilled, completed, and operated in compliance with applicable state and/or federal rules and regulations.”
But it also found 30 percent of the 50 natural gas wells reviewed were shallower than three nearby water wells. The natural gas wells are encased in cement, but that casing only extends as far as the well.
That means contamination from the natural gas well could leak into the water well below it. Yet more information is needed to prove a link between the two, the report found.
“The presence or absence of cement is only one of several factors to be considered in determining if a potential pathway exists behind the casing that could allow migration upward or downward,” wrote Robert King, the report’s author. “Other factors include hydrostatic pressure differentials, formation rock properties (permeability and porosity), gas/water contacts, location with respect to other wells, geologic and hydrologic environment, and drilling mud characteristics.”
Complicating matters further is a lack of information on the water wells drilled in the area. Seven of the 15 water wells reviewed for the report do not have a permit filed with the state Office of the State Engineer, which regulates water use. Information on when those wells were drilled, their depth and casing size, among other details, were missing, King found.
Also missing is information on what was done to stimulate the wells, the first of which were drilled in the 1950s. Chemicals used in fracking would fall under that umbrella.
King recommended the state obtain water well and stimulation information. Geologic and hydrologic studies are also needed to better understand the flow of gas and water between rock formations in the area, he said.
Mark Watson, Wyoming Oil and Gas Supervisor, cautioned against jumping to conclusions.
“Right now you only have one of the three reports,” he said. “You really can’t conclude anything until all of the three reports are submitted.”
The state is also investigating disposal pits in the region and testing the area’s water quality. The findings released Wednesday will be sent to Encana Oil and Gas, the operator of the field, and the EPA for comment and review.
The report will be then finalized and included as part of the state’s wider investigation.
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First Published August 5, 2014 8:00 PM