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Broad approach needed to pinpoint earthquake causes

Requiring oil and gas drillers to provide additional data and developing better maps that detail underground fault lines would help state officials — and the public — come to a better understanding of why the Earth is suddenly on the move in North Texas.

The ideas came during a sometimes testy meeting Friday in Austin between scientists and oil and gas industry representatives, who gathered to discuss an academic study that tied a series of earthquakes near Reno and Azle in 2013 and 2014 to nearby wastewater disposal wells.

Texas Railroad Commissioner Ryan Sitton suggested that the state not be myopic in its approach to conducting its research. He also urged Gov. Greg Abbott to sign a bill on his desk that approves $4.5 million for seismology equipment and a statewide earthquake study.

One participant suggested that it was simply “bad luck” that caused the earthquakes northwest of Fort Worth. Geologists and others also said that other earthquakes rattling northwest Dallas and Irving near the old Cowboy Stadium site are not related to oil and gas operations but may be near once-inactive underground faults that for some reason have come to life.

“If we only focus on the areas where there are disposal wells, we may be missing important information where there are no disposal wells, like Irving,” Sitton said in an interview after the meeting. The Railroad Commission regulates the oil and gas industry in Texas.

“This is not simply an oil and gas issue. This is trying to understand seismicity around the state and the range of things that are causing it,” he said after the meeting, which lasted more than four hours.

Sitton specifically called the meeting to discuss the study by Southern Methodist University scientists and others, published in April, that linked the earthquakes northwest of Fort Worth to disposal wells used in oil and gas drilling operations. Commission Chairwoman Christi Craddick and Commissioner David Porter did not attend.

While the scientists have continually pointed out that hydraulic fracturing — the act of injecting sand and liquids deep into rock formations to extract natural gas — is not the direct cause of the tremors, their studies found that high rates of wastewater and natural brine being forced into and sucked out of the Earth in the drilling process may be straining existing fault lines.

Related: Oklahoma coalition wants well moratorium in earthquake areas

Small change, big outcome

Matt Hornbach, one of the authors of the study, said a change of 1.5 pounds per square inch of pressure near a critically stressed fault can trigger significant changes. He said it may just be “bad luck” that the disposal wells near Reno and Azle were along one of these faults.

“It is very subtle changes that can cause these things,” Hornbach said. But “we’re talking about force changes of millions of pounds.”

Soon after the report was issued, the Railroad Commission asked XTO Energy and EnerVest Operating, which operate disposal wells in the area, to appear at “show cause” hearings next week to determine if their permits should not be canceled and their wells shut-in.

EnerVest officials at the meeting characterized SMU’s study as a good start, but they were critical of some of its findings, saying that their own review of the data did not match their analysis.

“When I look at the models in the paper, 11 out of 15 are very incorrect,” said Steve McDaniel, president and chief executive officer at EnerVest.

Dan Hill, a department head in petroleum engineering at Texas A&M University in College Station, said there wasn’t enough evidence in the paper to link the tremors to the disposal wells. He said the statements made in the SMU paper were too strong.

Statewide study

Sitton said he wanted to explore what additional data could be provided by the agency and what regulatory changes could be made to ensure that Texas’ oil and gas reserves continue to be developed safely, but with minimal economic impact.

Sitton said the agency may need to modify its rules on data gathering, but stopped short of committing himself to changes.

“It is our job as an agency to understand what is going on,” Sitton said. A mechanical engineer serving his first term on the commission, Sitton has often said that he could always use more data so that whatever decisions are made are “based on good sound science.”

He said the Legislature has been supportive of their efforts to get to the bottom of the earthquake activity. A $4.5 million appropriation is part of a supplemental budget bill that was sent to the governor for his approval.

Specifically, the budget amendment would ask for $2.47 million to buy 22 permanent seismograph stations and 36 portable stations as well as $2 million to analyze the data from any earthquake that exceeds magnitude 2.0 and identify it by date, location and depth. The equipment would augment the 16 seismograph stations that have already been placed in the area.


This article was written by Max B. Baker from Fort Worth Star-Telegram and was legally licensed through the NewsCred publisher network.