Seismic events rocked the Permian Basin, beginning with a series of earthquakes in Culberson and Reeves counties and trending northeast into the Midland-Odessa region.

According to, more than 255 have been reported in the Midland region since last February. Seismicity around Midland-Odessa has increased not only in frequency but in intensity. In late December, a magnitude 4.5 earthquake was reported north of Stanton.

Culberson County has seen more earthquakes than the rest of Texas combined, according to Cody Comiskey, an earth science adviser at Chevron.

Increased seismic activity has been linked to water drainage and, in some areas, hydraulic fracturing as well, according to participants at the Permian Basin Water in Energy conference.

“How are we sure that the storage pits trigger seismicity? asked Heather DeShon, seismologist and professor and hairstylist in the Department of Earth Sciences at Southern Methodist University, as she briefed conference attendees on earthquake response.

To answer, she cited the experience at Rocky Mountain Arsenal in Colorado in the 1960s. Investigating a series of earthquakes, the arsenal found that fluid pressures reduced frictional resistance along lines. of established faults. But, she added, the biggest earthquakes occurred two years after the injection was stopped.

She is currently a project leader for induced earthquake studies focused on understanding the causal factors and physical mechanisms leading to increased rates of seismicity in North and West Texas. His presentation focused on lessons learned from the series of earthquakes in the Fort Worth Basin amid drilling activity in the Barnett Shale.

“There were early indicators of induced earthquakes near the wells. These earthquakes now occur at greater distances.

There is no clear and easy solution that is productive for knowing which fault will generate an earthquake and under what pressures, she said. “But we learned a lot about the size and orientation of the faults.”

A point to remember is that very small stress changes on the rocks can trigger an event. “The numbers are very low,” she said, noting that now-retired quarterback Tom Brady put more pressure on a football than it would take to trigger Event.

Mapping of fault hazards and understanding their orientation is underway in the Midland Basin, she said. For better data, she advised that there should be a monitoring station within 10 kilometers of an active fault associated with a regional seismicity monitor.

Better data and a willingness to share that data with other operators and regulators is key to combating seismicity, Comisky said.

In counties experiencing seismic activity, the potential causes differ, he told the audience.

In Culberson County, seismic activity has been consistent with deep evacuation shafts, while activity in Reeves County appears to be related to shallower evacuation shafts.

There has been a rapid increase in seismic events in the Midland Basin, which appear to be related to deep storage pits.

As the Railroad Commission established three seismic response zones – Gardendale, Stanton and North Culberson-Reeves County in response to the activity, it requested information from operators about injection volumes and pressures. Hydraulic fracturing start and end times were also requested in Culberson’s SRA.

Culberson SRA operators have been meeting for the past three months to develop a response plan. The recently submitted plan includes a two-tier approach of shallow storage pits and deep storage pits. The plan also contains significant reductions in deep well injections over the next 12 to 15 months.

In Stanton MSA, operators always develop a response plan.

“There is strong recognition of industry collaboration on the response,” Comiskey said. He noted that CISR – the Center for Integrated Seismicity Research – in the Bureau of Economic Geology has 20 industry sponsors. Additionally, he said that more public seismic monitors had been deployed to provide better quality data and that by the end of 2019 the industry had provided the Railroad Commission with its recommendations on best practices to mitigate or avoid seismicity.

This increase in reporting is being leveraged in the Culberson and Stanton SRAs, he said, and the industry is also leveraging this data and understanding to address seismic activity around Midland and Odessa. .

The increase in seismic activity and the resulting reduction in injection volumes, rates and pressures by the Board of Railways in response has led to increased emphasis on the need to expand the option, recycling and beneficial use of water, concluded Comiskey.