The ongoing earthquake swarm has brought together regulators, scientists and the oil and natural gas industry to help determine what is causing the quakes and what, if anything, can be done to stop them or minimize the risk they pose.
Earlier this year, the parties worked together to develop new rules for new and existing water disposal wells. The Oklahoma Corporation Commission has not made a determination as to whether the wells are to blame, but the commissioners and staff have strengthened rules in an effort to gain more information and minimize risk.
“I haven’t seen anything in what I’ve reviewed that would cause me to come to the conclusion that the injection wells are causing this swarm. I see it as still unknown,” Commissioner Dana Murphy said. “Whether we know exactly what’s causing this or not, we need to move in the direction we’re moving.”
New rules that become effective Sept. 1 require disposal well operators to monitor volumes and pressures daily and to make that information available to commission staff or Oklahoma Geological Survey staff upon request.
The more up-to-date information is designed to help researchers and regulators determine whether specific quakes are centered near injection wells that have particularly high pressure or volumes at the time of the rumbling.
“I think the main thing we have to do now is continue to collect data,” Commissioner Patrice Douglas said. “We want to make decisions that benefit Oklahoma and that provide safety for Oklahomans. We have to continue to collect data and continue to have these open streams of communication, not just with industry, but also with seismologists that are employed in the industry and outside the industry.”
Red light, green light
The commission also has developed a graduated system of approving new disposal wells. If no risk factors are identified, the proposed well receives a green light to begin construction. If one or two risk factors are identified, the well receives a yellow light and is subject to further discussion and investigation. If there are too many risks or concerns, the project is rejected.
The commission also is paying special attention to disposal wells within seven “areas of interest” in central and northern Oklahoma. The areas are near the epicenters of the 20 magnitude 4.0 or greater quakes the state has experienced over the past five years.
Oklahoma is dotted with nearly 12,000 water injection and disposal wells. Corporation commission staff are paying special attention to the 97 disposal wells within the areas of interest.
The commission, the state geological survey and industry leaders also have developed a much clearer picture of natural faults that crisscross central Oklahoma.
Southwestern Oklahoma rests above the Meers fault, which is known to have been active in geological history. But the extent of the faulting in central Oklahoma is only now becoming well documented.
Oil and natural gas companies over the past 15 years have used three-dimensional seismic imaging to develop a much clearer picture of the rock layers that underlay the state.
The expensive and proprietary data and maps they have produced have been used by companies to choose the best locations for wells and to guide sophisticated horizontal drilling techniques that can bury a well bore for up to two miles in length in a rock lay that may be only a few dozen feet thick.
The 3-D images also detect natural fault lines.
Companies initially were reluctant to share proprietary imaging data, but as part of the joint group with the Corporation Commission and Oklahoma Geological Survey, the fault data has been pooled and distributed. As a result, maps that just six months ago showed a smattering of fault lines now are covered in lines portraying the thousands of natural fractures that are found throughout much of central Oklahoma.
Companies and regulators can use the new information to help avoid natural faults when new disposal wells are drilled.
Oilman Kim Hatfield said companies are working with regulators and researchers, but that they do not believe their industry is contributing to the earthquakes.
“Since we know the possibility exists, we want to make sure we’re doing everything we can to avoid the circumstances that might accidentally trigger something,” said Hatfield, regulatory committee chairman for the Oklahoma Independent Petroleum Association. “Even if 99.999 percent of these are naturally occurring, if one is induced, that’s not a good thing. We’re doing everything we can to make sure we avoid that one.”