Drilling Down

Pa. Finds Fracking Caused Lawrence County Quakes

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MEADVILLE, Pa. – A series of low-magnitude earthquakes that occurred in Lawrence County in April 2016 were most likely caused by hydraulic fracturing, according to a report issued Friday by the Pennsylvania Department of Environmental Protection.

“Induced seismicity is a relatively new and complex technical issue,” said Patrick McDonnell, acting secretary of the department. “This report reflects our commitment to understand what occurred, through extensive review with scientific and industry partners, and to formulate procedures to reduce seismic risk going forward.”

Early in the morning of April 25, the Pennsylvania Seismic Network recorded four earthquakes ranging from 1.8 in magnitude to 2.3 in magnitude on the Richter scale in Mahoning, Union and North Beaver townships.

DEP said that tremors were so light that they most likely would go unnoticed by humans.

The quakes occurred near a well pad owned by Hilcorp Energy Co., which was using a technique called “zipper fracturing” – a hydraulic fracturing process that simultaneously fracks two horizontal wellbores that run parallel to each other. Hydraulic fracturing started at the well pad on March 30.

When DEP contacted Hilcorp about the quakes, the company voluntarily shut the well pad down and has discontinued hydraulic fracturing at the pad indefinitely.

Hilcorp’s North Beaver NC Development pad consists of four wells, two of which were completed at the time of the tremors. Two other wells were undergoing hydraulic fracturing when the quakes occurred.

In the report, DEP recommends halting zipper fracturing when there is less than ¼ of a mile between the lateral legs of two adjacent wellbores. Also, the DEP recommends that Hilcorp maintain operation of its own seismic network.

Among the other recommendations in the report is a response plan says Hilcorp should notify DEP with in 10 minutes via email and one hour by telephone if there is seismic activity of 1.0 or greater magnitude within six miles of the wellbore path.

Any succession of three seismic events ranging from 1.5 to 1.9 in magnitude during a three consecutive-day period and within three miles of the wellbore path should include suspension of stimulation activity, submittal of seismic data to DEP and a plan detailing modifications to hydraulic fracturing operations.

Any seismic event of 2.0 or greater that occurs within a three-mile radius of the wellbore path would require stopping all stimulation activity at the well site, conducting flow back of the well, and submission of seismic data to the DEP for review, as well as a plan detailing any modification to future stimulation procedures.

In November, DEP approved a seismic monitoring plan submitted by Hilcorp that incorporates all of these recommendations, the DEP said. The agency has also recommended that other operators follow similar plans within Union, North Beaver, and Mahoning townships.

Published by The Business Journal, Youngstown, Ohio.