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Proactive Approach Urged to Prevent, Better Understand Induced Seismicity

A former top official at the Ohio Department of Natural Resources (ODNR) says the issue of induced seismicity related to oil and natural gas activity is not going away anytime soon, and he urged both the industry and state regulators to work to ease public concern and prevent future incidents.

Tom Tomastik, a senior geologist and regulatory specialist at Oklahoma-based ALL Consulting, said earthquakes caused by human activity, such as those related to drilling wells or injecting waste underground, is a national issue that will require more monitoring, more data sharing and more attention from operators.

"Induced Seismicity, even though it's in the media, it's extremely rare. But it's a nationwide issue and it's not going away anytime soon," Tomastik told a crowd gathered for the Ohio Oil and Gas Association's Oilfield Expo in Cleveland on Thursday. "I think it's really crucial that the oil and gas industry approaches the issue of induced seismicity proactively with good sound sciences, and we need to work in cooperation with regulatory agencies to address this and see how we can identify any geological features that might be causing some of these events."

Tomastik, who formerly served as lead geologist of ODNR's Underground Injection Control Program, said seismic events related to oil and gas activity were first recorded in the 1960s. Although they haven't been linked to the oil and gas industry alone, the shale boom has attracted more public attention to a series of events in recent years in Arkansas, Ohio, Oklahoma, Kansas and Texas in which earthquakes were tied to underground injection wells and even horizontal hydraulic fracturing (fracking).

Those states have, or are developing, new regulations to ease public concerns about the earthquakes, but Tomastik said that's not enough.

"Regulation of oil and gas tends to be reactive, not only in Ohio, but across the United States," he said, "something happens and it gets in the media, gets to the public, gets to the government, and what's the response? The government swings into action and you get regulatory measures designed to prevent future incidents. Is that a knee-jerk reaction? I think it is because it's not typically based on sound science."

Tomastik cited a recent example of how operators can do more to help state regulators. He pointed to an incident in March when four earthquakes, ranging in size from a 2.2-magnitude to 3.0-magnitude were recorded at a Hilcorp Energy Co. site near Youngstown, OH (see Shale Daily, March 11). It was learned that Hilcorp had been stimulating a well at the site that likely caused the earthquakes (see Shale Daily, March 12) .

At the time of the earthquake, the company had been conducting zipper fracks on two wells at the site, said Tomastik, who worked for ODNR at the time. The company was pumping 100 bbl per minute of frack fluids at 10,000 psi. ODNR discovered that half way through a frack stage, "when the seismic event occurred," Tomastik said, the fluid rate dropped to 70 bbl per minute and the pressure spiked.

"It was like they hit something hard and the fluid just broke loose," he said. "So, there was very good evidence that something did happen in that frack stage that caused the earthquake."

Regulators working with Hilcorp learned that a Precambrian fault line did run beneath the company's pads. But Tomastik said the company had no idea until it went back to examine its 2-D and 3-D seismic data.

ODNR has since issued more stringent permitting standards for wells near known fault lines (see Shale Daily, April 11). It also moved to install a network of seismic monitoring devices across eastern Ohio after a 4.0-magnitude earthquake on New Year's Eve 2011 (see Shale Daily, May 22; Jan. 4, 2012). Tomastik said more monitoring devices will be needed in Ohio and across the country to gather as much data as possible about earthquakes when they occur near well sites.

He added that operators must pay closer attention to their own seismic data and be more willing to share it with regulators in the public sector, where in some places geological information is limited.

"I think we're going to have to be willing to share, to some extent, some of the seismic data," he said. "Somehow, we have to be willing to work with the regulatory agencies to show them some of the technology we've used to identify things. I'm not saying give it to them so that it becomes public record, but at least work with them and show them there are other geologic structures out there that we need to be looking at."

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