EPA, Texas at Odds Over Wells and Quakes

WEDNESDAY, AUGUST 24, 2016


Federal and state officials seem to be at odds over the effect oil and gas drilling are having on seismic activity in northern Texas, as a new review from the Environmental Protection Agency suggests it’s possible that earthquakes in the region have been caused by disposal wells.

In its end-of-year report on the Texas Railroad Commission (RRC)’s Underground Injection Control Program, dated Aug. 15, the EPA notes that while the RRC “publicly indicated that available scientific data do not sufficiently support a causal relationship between Class II waste disposal wells in North Texas and recorded earthquakes … EPA believes there is a significant possibility that North Texas earthquake activity is associated with disposal wells.”

Wells and Seismicity

There has been a growing consensus among federal officials that disposal wells at hydrofracturing and other gas and oil extraction sites have led to seismic activity in regions where they have been created. Disposal wells are underground sites where wastewater from drilling activity is injected.

Earlier this year, the United States Geological Survey, a federal research agency, began reporting “induced” seismic activity alongside “natural” earthquakes for the first time. Texas was among the states the USGS singled out as being most at risk for induced earthquakes. Experts speculate that the injection of the wastewater can “lubricate” fault lines and the pressurized fluid can induce movement in faults.

USGS earthquake map, eastern U.S.

Earlier this year, the USGS began reporting “induced” seismic activity alongside “natural” earthquakes for the first time.

In early 2015, the EPA produced a report on induced seismic activity related to the oil and gas industry; one section analyzed earthquakes recorded in the North Texas region in 2008 and 2009, speculating on the possible role of disposal wells.

Texas Regulations

The RRC is the state’s regulatory body governing extraction of oil and gas. In 2014, it introduced rules taking past seismic activity into account when issuing permits for disposal wells, and allowing for the revocation of permits “if injection is likely to be or determined to be causing seismic activity.”

Disposal well diagram
U.S. EPA

Experts speculate that the injection of the wastewater can “lubricate” fault lines and the pressurized fluid can induce movement in faults.

According to the new EPA report, the RRC addressed earlier, potentially induced earthquake activity in the Dallas-Forth Worth area, leading to voluntary reductions in volume and well closures that corresponded with a reduction in seismic activity.

But the RRC hasn’t come out and confirmed the wells as a possible cause of the activity in the past, as the EPA does in its new report.

Concerns Over Water Sources

The EPA expresses concern in the report over the seismic activity as it relates to public health and safety, including underground water sources in the Dallas-Fort Worth area. The agency recommends that the RRC monitor injection volumes and pressures in the area in order to analyze whether injections might correlate with earthquake activity.

The preferred site for the injection of waste fluid in the region is the Ellenburger Formation, the agency explains, which could account for issues related to seismicity. That formation includes natural fractures that may conduct the water miles away, and lead it down to deep faults, it surmises.

The Barnett Shale, a source of natural gas in the Dallas-Fort Worth area, lies in a layer immediately above some portions of the Ellenburger Formation.

In nearby Oklahoma, more than 400 disposal wells were shut earlier this year as part of an earthquake response plan. According to Oil and Gas Journal, Oklahoma recorded a more than 50 percent uptick in earthquakes of magnitude 3.0 or greater from 2014 to 2015—from 578 to 900.

   

Tagged categories: Asia Pacific; EMEA (Europe, Middle East and Africa); Environmental Protection; Environmental Protection Agency (EPA); Health & Safety; Latin America; North America; Oil and Gas; Regulations

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