Encana halts completion work after earthquakes

Newfield/ Encana on Thursday stopped completion efforts on a well it drilled in the STACK play of northwestern Oklahoma after two stronger earthquakes that affected Kingfisher County were associated with its work.

The Oklahoma Corporation Commission announced the company decided to end hydraulic fracturing work at the unidentified well about eight miles west of Kingfisher after consulting with the agency's Induced Seismicity Department.

According to Oklahoma Geological Survey records, recent stronger earthquakes have affected two areas in Kingfisher County — the area near the Newfield/ Encana well west of Kingfisher, and another about four miles north- northeast of Loyal. Both appeared to be associated with well completion work.

As for the Newfield/Encana well, the Oklahoma Geological Survey recorded a 3.2 magnitude earthquake Wednesday evening, which prompted the operator to pause completion work to re-evaluate its plans.

Then, early Thursday, a 3.9 magnitude earthquake was observed near the well while the work was still halted.

Oklahoma State Seismologist Jake Walter said the latter event is the strongest seismologists have ever observed related to well completion work in Oklahoma, if that turns out to have been the cause.

“We will be evaluating what factors might have contributed to the event, based on the limited public regulatory information that we have,” Walter said.

The other recent instance of induced seismicity believed to have been associated with completion work on a STACK well was observed about 9:30 p.m. Wednesday, when 3.33 and 3.03 magnitude events occurred as hydraulic fracturing was underway on Chisholm Oil and Gas Operating's Cattle Drive 18-09-23 No. 1MH.

That operator, following regulatory protocol, suspended those completion operations for six hours to re- evaluate plans, before resuming the completion job without further observed issues.

The protocol for dealing with induced seismicity suspected to be caused by completion activities was adopted in late 2016 for operators in the South-Central Oklahoma Oil Province and Sooner Trend Anadarko Basin Canadian and Kingfisher counties (STACK) plays.

In early 2018, the protocol was tightened as regulators sought to address increased observance of seismic events in those plays.

The tightened protocol required that all operators in the defined area have access to a seismic

array capable of providing them with real-time readings.

It also required operators to suspend operations after observing a magnitude 2 or greater event during completion operations.

Generally, the minimum magnitude level at which earthquakes can be felt is a 2.5.

On Thursday, Walter stated monitoring efforts conducted by the

Oklahoma Geological Survey provides valuable data to regulators as they continue to look at induced seismicity issues.

Pausing and re-evaluating completion efforts in many cases allows underground pressure to bleed away before work resumes, he observed.

But he reiterated additional financial resources are needed by the Oklahoma Geological

Survey to create a more robust monitoring network to enhance the data scientists and regulators need to grow their understanding of the phenomenon.

“It helps inform the public and promotes safety around these hydraulic fracture completion operations. But we can't do that without investment in our seismic network infrastructure,” he said.