The state Department of Environmental Protection has attached requirements to future permits of Hilcorp Energy for any fracking specific to an area of Lawrence County where mild earthquakes occurred last year.
Seth Pelepko, chief of the division of well plugging and subsurface activities in DEP’s Bureau of Oil and Gas Planning and Program Management, addressed the relationship between Hilcorp’s drilling to four low-level earthquakes that began at about 4:15 a.m. April 25 in Mahoning, North Beaver and Union townships.
Pelepko detailed the information about the local seismic activity during a webinar hosted Friday by the DEP.
“What we can say based on data that’s available ... is that this is the first time (in Pennsylvania) we have seen that spatial and temporal correlation with operator activity,” he noted, referring to the earthquakes.
Patrick McConnell, acting DEP secretary, showed that the earthquakes that occurred in that area of the county on those dates registered between 1.8 and 2.3 on the Richter Scale, and were considered “microseismic.” A microseismic event registers at 3.0 or less and is generally not felt but is recorded by seismometers.
Pelepko explained that the occurrences locally that day were from “an induced tectonic seismic event,” meaning that the contributing factors of the quakes were caused, and not naturally occurring. A compilation of observations suggests there was a relationship between the event and operator activities, he said.
Hilcorp’s New Castle Development Pad in North Beaver Township lies within a five-mile radius of the reported epicenters. Hydraulic fracturing activities began at the pad on March 30. The Utica Shale was being hydraulically fractured at 7,900 feet below the ground surface, a separation of 2,500 to 3,000 feet from crystalline rock, he said.
Hilcorp was using a technique known as “zipper fracturing,” which the DEP explained as hydraulic fracturing operations that are carried out concurrently at two horizontal well bores that are parallel and adjacent.
“Hilcorp immediately and voluntarily stopped all activities and discontinued those activities indefinitely as of noon on April 25,” Pelepko said, adding that the last earthquake was on the morning of April 26.
Pelepko added that the well site lies north of the Rome Trough, a noted geological feature that is an elongated depression. Fracturing there is much closer to basement rock, he said, making the area more prone to seismic activity.
In response to the Lawrence County earthquakes, the DEP published a formal report regarding its recommendations to Hilcorp. Pelepko said that Hilcorp has adopted the plans. Those recommendations were made to Hilcorp in September or October and are part of an ongoing development process, he said.
The recommendations for Hilcorp’s well drilling in that entire area include discontinuation of the practice of zipper fracturing when there is less than a quarter-mile between lateral portions of adjacent well bores. In addition, it is recommended that Hilcorp maintain operation of its own seismic network within these townships to allow for the accurate detection of local, low-magnitude events. Other recommendations involve notifying the DEP about seismic events that occur.
On Nov. 16, the DEP approved a seismic monitoring plan submitted by Hilcorp that implements the DEP recommendations. DEP also has recommended that those terms apply to any new permits granted to Hilcorp and that other operators follow similar plans within the referenced townships.
Hilcorp is complying, Pelepko said, and one permit has since been issued to the company in a township that has the recommendations applied as permit conditions, he said.
Contacted later on Friday, Justin Furnace, Hilcorp Energy Co.’s director of external affairs, commented by email that the company is reviewing the DEP’s report regarding the April 2016 Lawrence County microseismic events.
“At this time we do not have a comment on the report itself,” he wrote. “As noted by DEP, we immediately discontinued our activity on the well pad in question. We have no immediate plans to resume completion activities on the well pad. We will continue to work with DEP to implement the plan outlined in the report.”
The DEP meanwhile is developing “field rules” that allow it to look at conditions throughout the oil- and gas-producing regions of the state and to develop recommendations that apply specifically to those areas, Pelepko said.
Penn State University conducted a study in 2013 and 2014 with seismic data and has been monitoring earthquake activity statewide, he added. There are 41 seismic monitoring networks throughout the state and in parts of neighboring Ohio. The DEP has taken steps to ensure that all earthquake events are recorded, and the analysis by Penn State allows it to determine if an occurrence is a surface-disturbing or a natural event, he said.
“This is a developing science. We are paying close attention to earthquakes of any kind and monitoring activities to determine how they are affecting different parts of Pennsylvania.”
CNHI News Service