The Pennsylvania Department of Environmental Protection says it found a link between fracking and a series of low-magnitude earthquakes in Lawrence County.
The quakes were recorded last April about 50 miles north of Pittsburgh and three-quarters of a mile from a natural gas well owned by Houston-based Hilcorp Energy Co. They were too weak to be felt by people and no damage was reported.
DEP’s report released this morning says the quakes had a “marked … relationship” to Hilcorp’s drilling operation in terms of timing and location.
Fracking has been tied to earthquakes in neighboring Ohio and other states, but never in Pennsylvania.
DEP News Release:
Meadville, PA – Seismic events that occurred in western Lawrence County on April 25, 2016, had a “marked temporal/spatial relationship” to natural gas hydraulic fracturing by Hilcorp Energy Company, according to a report by the Pennsylvania Department of Environmental Protection (DEP).
“Induced seismicity is a relatively new and complex technical issue,” said DEP Acting Secretary Patrick McDonnell. “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.”
The Pennsylvania Seismic Network registered four low-magnitude earthquakes beginning at 4:17 a.m. in North Beaver, Union, and Mahoning Townships. (OhioSeis recorded three earthquakes, and Lamont-Doherty Cooperative Seismic Network recorded five.) The final magnitude of the earthquakes ranged from 1.8 to 2.3 on the Richter Scale, putting them in the category of microseismic events, which are likely to go unnoticed by humans and only recorded by sensitive seismic monitors.
Hilcorp’s North Beave NC Development well pad, which includes four wells drilled into the Utica Shale Formation, lies within a five-mile radius of the reported epicenters. Hydraulic fracturing activities began at the pad on March 30.
Hilcorp was using a technique known as “zipper fracturing,” or hydraulic fracturing operations that are carried out concurrently at two horizontal wellbores that are parallel and adjacent to each other. When DEP contacted Hilcorp on April 25, the company voluntarily stopped activities and later reported they would discontinue hydraulic fracturing and stimulation operations at the well pad indefinitely.
Recommendations in the DEP report include discontinuation of the practice of zipper fracturing during any future completions when there is less than a ¼ mile between lateral portions of adjacent wellbores. This applies to Hilcorp’s Utica gas wells in North Beaver, Union, and Mahoning Townships. Zipper fracturing is allowed when there is more than ¼ mile distance between lateral portions.
In addition, it is recommended that Hilcorp maintain operation of its own seismic network within these townships. The seismic network will allow for the accurate detection of local, low-magnitude events.
A seismic event reporting schedule and operator response plan is also included in DEP’s recommendations:
• For seismic events of 1.0 or greater magnitude occurring within 6 miles of the wellbore path, the company should notify DEP within 10 minutes via email and within one hour by telephone.
• For any succession of three seismic events of 1.5 to 1.9 magnitude that occurs within a three-consecutive-day period and within a 3-mile radius of the wellbore path, Hilcorp should notify the DEP within 10 minutes via email and within one hour by telephone. Actions taken for this magnitude range of seismic events include suspension of stimulation operations, submittal of seismic data to DEP for review and a plan detailing modifications to stimulation operations.
• Finally, for any seismic event of 2.0 or greater magnitude that occurs within a 3-mile distance of a wellbore path, Hilcorp should notify the DEP within 10 minutes via email and within one hour by telephone. Actions taken include cessation of stimulation operations, flowing back of the well, submittal of seismic data to DEP for review and a plan detailing any potential modification to stimulation operations.
On November 16, 2016, DEP approved a seismic monitoring plan submitted by Hilcorp implementing the recommendations set forth in the DEP report.
DEP has also recommended that these terms apply to any new permits requested by Hilcorp and that other operators follow similar plans within the referenced townships.
See the DEP website for the report, a webinar discussion, and more information on the seismic events.