By Luc Cohen
HOUSTON (Reuters) - An oil and gas regulator in the top U.S. energy-producing state of Texas cast doubt on research linking growing seismic activity to petroleum production on Wednesday, following the release of a study arguing most of the state's earthquakes are manmade.
Ryan Sitton, one of three members of the Texas Railroad Commission, which regulates the oil and gas industry, told a Houston Bar Association gathering that studies linking earthquakes to disposal wells for wastewater produced as a byproduct of oil and gas production were based on "very aggressive assumptions that you would not normally accept in a scientific study."
The comments came on the same day researchers released a paper arguing that as many as nine in 10 of Texas's earthquakes in the past 40 years may have been caused by oil and gas production, raising the specter of greater regulation in a state that produces 20 percent of U.S. energy output and is home to some of the country's hottest shale plays.
Following a speech touting the role of the oil industry in Texas' economy and criticizing the Obama administration's carbon emission regulations, the first audience question Sitton faced was on whether the commission was looking into reports linking earthquakes to fossil fuel production.
"If seismicity is being caused by oil and gas activities, then I want to know it, and we're going to regulate it," Sitton said. "But if not, I don't want somebody in parts of the state to be convinced it's oil and gas and not address whatever the real issues are."
Texas's earthquake issue pales in comparison to northern neighbor Oklahoma, where regulators have clamped down on disposal well volumes as a result of growing seismicity. But University of Texas-Austin researcher Cliff Frohlich, the lead author of Wednesday's study, said Texas regulators have been too slow to acknowledge a link.
Studies like Frohlich's have been criticized by the Railroad Commission and industry groups for relying too heavily on correlations between the spacing and timing of earthquakes and disposal wells and not enough on subsurface pressure data.
"This is not the time for anybody - the Railroad Commission, academia, federal or state jurisdictions - to be putting out half-cocked information," Sitton said in an interview on the sidelines of the meeting.
Frohlich defended his methods in an interview, noting that Texas contained relatively few seismic monitoring stations and praised a recent state decision to install more.
(Reporting By Luc Cohen; Editing by Terry Wade and Jonathan Oatis)