Most Texas Quakes Likely Caused by Oilfield Activities

Most Texas Quakes Likely Caused by Oilfield Activities
Most Texas Quakes Likely Caused by Oilfield Activities

Oil and gas activities may have caused nearly nine in 10 of the earthquakes Texas has experienced in the past 40 years and the quakes have become more frequent, as oilfield activity has picked up in the past decade, according to a study reported by Reuters.

Of the 162 Texas earthquakes of magnitude 3 or greater between 1975 and 2015, a quarter were "almost certainly" induced by oil and gas activities, while 33% were "probably” induced and 28% were "possibly” induced, researchers led by University of Texas-Austin geoscientist Cliff Frohlich wrote.

A sharp uptick in oil-linked earthquakes has caused a popular uproar and regulatory scrutiny in northern neighbor Oklahoma.

While the phenomenon is not nearly as widespread in Texas, the paper shows the United States' hottest shale plays are not immune to increased seismic risk.

The researchers also criticized the Texas Railroad Commission, the agency responsible for regulating petroleum production in the state, for being "slow to acknowledge that induced earthquakes occur in Texas".

Since shale oil and gas fields like the Haynesville and the Permian boomed in 2008, the rate of earthquakes exceeding magnitude 3.0 has increased from two per year to 12 per year in Texas, the top U.S. oil state.

This so-called unconventional production generates two to three times more wastewater than in conventional oilfields and has boosted the amount of water that must be injected deep underground into disposal wells, which have been linked to the recent wave of quakes in Texas and Oklahoma.

Oklahoma, where large amounts of water naturally come out of wells along with oil and gas, saw 890 earthquakes of magnitude 3.0 and above in 2015 alone, compared with two to three a year before 2009.  The authors acknowledged that the majority of disposal wells and petroleum fields in Texas had not been associated with earthquakes.

"Nevertheless ... we cannot dismiss the correlations in time and space over a long operational history," the authors write.

A Texas Railroad Commission spokeswoman dismissed the study as "arbitrary" and "subjective" and said the agency had also taken steps to reduce injection volumes.