Considering the amount of fracking going on in the United States, any coincident increase in related seismic activity is relatively small, an engineering professor and fracking entrepreneur told an audience at the Conference of Western Attorneys General's Colorado Energy Summit on Wednesday.
While it has been documented in other parts of the world as well as in the United States that quakes have been associated with oil/gas production, William Fleckenstein, head of petroleum engineering at the Colorado School of the Mines, said the U.S. association of quakes with oil/gas work has not been with fracking, per se, but rather with fracking water disposal wells.
Fracking and the disposal of the fracking water "are two different things," Fleckenstein told Summit attendees in Denver. "But the news media picks up on the seismicity and says it has to be caused by fracking, and therefore, that is what a lot of people believe."
Fleckenstein, who as a entrepreneur has developed some patented fracking technology advances, contends that when the fracking process ceases, any seismic activity goes away. "Historically, when [wastewater] injection stops, the seismicity stops," he said.
He said there have been close to 1.5 million hydraulically fractured wells now in the United States, and there has not been very much seismicity associated with it. "It is kind of a new topic, and people are trying to understand the data, but so far, there is just not much data to look at.
"So far, the seismicity has been pretty small and has been something that you almost can't feel at all, and if you do, it is very slight. And it appears that it does not lead to larger earthquakes that have been associated with it."
For Fleckenstein, the amounts of data on the seismic questions is still too small, and he is convinced that given the overall volume of fracking ongoing these days, "there just hasn't been a tremendous amount of seismicity associated with [fracking]."
Noting that the combination of horizontal drilling and hydraulic fracturing have changed the U.S. energy landscape, Fleckenstein said shale development is "really a worldwide phenomenon because we don't have any kind of corner on the rocks necessary for it."
Based on his experience as a petroleum engineer working in California in the 1990s, Fleckenstein said it is important to know how close drilling activity is to known faults, both active and dormant. "In California, as soon as the drilling activity stopped, the seismicity went away," he said.
"One of the key things we would do in California was to make sure we were not in, or near, a fault. The ability to identify faults beforehand is obviously a very important thing to do."
Just recently, Ohio regulators established what is believed to be the country's first set of permitting conditions for hydraulic fracturing (fracking) in horizontal wells near fault lines or areas of previous seismic activity (see Shale Daily, April 11). The move comes after a month of investigation into the cause of a 3.0-magnitude earthquake on March 10 near a well pad about eight miles southeast of Youngstown (see Shale Daily, March 11).
In a press release announcing the new regulations, ODNR said its geologists believe that sand and water injected into one of the six wells on the pad during stimulation operations in the days leading up to the earthquake (see Shale Daily, March 12) increased pressure on an unknown micro-fault in the area, triggering the seismic activity.
A series of recent small quakes in Oklahoma have triggered speculation as to whether they are linked to hydraulic fracturing or to injection of wastewater into underground wells. A producer spokesman suggested that since "oil and gas production is found in 70 of Oklahoma's 77 counties. [Thus,] any seismic event is likely to occur near oil and gas activity, but that does not mean oil and gas activity is the cause." (see Shale Daily, April 8).