The three-member Texas Railroad Commission on Tuesday accepted the findings of the commission staff that two oil and gas wastewater disposal wells were not the likely cause of a series of earthquakes that shook parts of North Texas in late 2013 and early 2014.
The decision, which the commission made in an open conference meeting Tuesday morning, clears the two injection wells, owned by Houston-based Enervest and ExxonMobil subsidiary XTO Energy, respectively, of responsibility for the minor quakes felt by residents in the small cities of Azle and Reno.
About three dozen earthquakes were reported in Azle and the surrounding area. Most were considered minor, registering about 3.3 magnitude or less.
TRC hearings examiner Paul Dubois reported the results of hearings held last summer to determine if the wells contributed to the unusual seismic disturbances that had alarmed residents of the area, which lies in the heart of the Barnett Shale gas-producing play.
In August, TRC hearings examiners found the XTO West Lake SWD, Well No. 1, near Reno, was not the likely cause of the quakes, and in September, the hearings examiners issued a similar finding for the nearby Enervest Operating Briar Lease, Well No. 1.
The commission decision seems to be in conflict with a study released in April by researchers at Southern Methodist University, which pointed to the injection wells as the likely cause of the rash of quakes in North Texas.
However, Dubois said the evidence based on the data collected by the SMU researchers was too weak to establish a causal relationship between injections of wastewater into the two wells and the series of temblors.
Railroad Commissioner Ryan Sitton praised Dubois and the hearings staff for doing "a really good job of getting to the technical meat of this issue."
Sitton said the commission has done a great deal of work on the issue of induced seismicity in the past year and a half, including hiring seismologist David Craig Pearson, a former team leader for a Los Alamos National Laboratory seismic team in March 2014.
In addition, Sitton said he has met with energy industry regulators in Oklahoma, who are wrestling with similar issues of induced seismicity in their state.
"I support the efforts that you guys made," Sitton told Dubois.
