The Railroad Commission of Texas (RCC) said June 12 it completed its analysis of fall-off pressure test results from five disposal wells in Johnson County.

The tests were ordered following a reported 4.0 magnitude earthquake which occurred in the area on May 7, pursuant to the commission’s rules on seismicity adopted last year.

The commission said the test results didn't indicate any bounding faults in the immediate vicinity of the wells tested. At this time, there is no conclusive evidence the disposal wells tested were a causal factor in the May 7 seismic event, the commission concluded.

The commission's staff of seismologist, geologists, and petroleum engineers conducted the tests to help determine the effect of injection operations on pressures within subsurface rock formations.

The five wells tested are all within 100 square miles of the estimated epicenter of the seismic event, as prescribed in commission rules addressing seismicity. The operators of the wells cooperated fully with the Commission in conducting these tests.

The operators are:

  • Bosque Disposal System LLC;
  • EOG Resources Inc. (EOG)—two wells;
  • MetroSaltwater Disposal Inc.; and
  • Pinnergy Ltd.

“We appreciate the cooperation of the operators to voluntarily shut down and collect data that will help us better understand what, if any relationship there is between these wells and seismicity,” said Craig Pearson, the commission's seismologist, in the release.

The commission said it will continue to work closely with seismic researchers and industry to collect, analyze and evaluate seismic data, geological information and oil and gas activity in the region to determine if there is any connection.

“While we can’t say at this time there is a connection, this is the beginning of the process, not the end in analyzing and understanding whether there is any correlation and what, if any action by the commission may be necessary in the future to protect public safety and our natural resources,” Pearson added.