WEBBVILLE — If the continued interest in exploring for oil far below the surface of northeastern Kentucky ever results in a production boom, researchers will be ready to gauge the effect on earthquakes.
Seismologists with the Kentucky Geological Survey at the University of Kentucky are installing a network of highly sensitive seismic monitoring stations in the area this summer.
Other parts of the country have experienced more low-level earthquake activity after an increase in the use of high-pressure hydraulic fracturing, or fracking, to produce oil and gas. That matters in Kentucky because there could someday be far more drilling and fracking of deep, horizontal wells in an ancient geologic layer called the Rogersville shale.
Several companies have drilled test wells in Lawrence and Johnson counties to explore the Rogersville.
Seth Carpenter, a seismologist with the Kentucky Geological Survey, is leading a project to install at least 15 stations in the region to measure ground movement.
The goal is to collect baseline data on earthquake activity in the region before any significant increase in oil production there. Then, if that development comes, researchers will have better information to measure its impact, if any, on the number and strength of earthquakes.
"That's the primary benefit to the state," Carpenter said.
There are seismic monitoring stations in the region now, but the ones Carpenter and colleagues are installing are more sensitive and are being placed closer together, so they can register smaller earthquakes. The new stations also will help provide information to better assess the earthquake hazard in the area.
Interest in the Rogersville shale spiked beginning about two years ago based on research that showed the shale could hold significant amounts of oil and gas.
There has been oil and gas development in the area for decades, but not in the Rogersville shale layer, which lies 9,000 feet or more below the surface.
Companies signed hundreds of new leases with mineral owners in the area in 2013 and 2014.
The potential to develop the deep shale layer results from a combination of horizontal drilling and fracking.
Traditional oil wells involve drilling a vertical hole. However, companies developed the ability to curve the pipe as it proceeds underground, meaning it goes down a certain depth and then travels horizontally in a band of rock containing oil or gas, allowing producers to tap a bigger area.
Companies are believed to have drilled — or gotten permits to drill — at least half a dozen deep wells in Lawrence and Johnson counties since 2013 to figure out whether there is sufficient oil in the Rogersville shale to justify commercial development, according to people familiar with the issue.
Companies are allowed to keep much information about test wells secret, but it's clear there is a good deal of interest, said David C. Harris, who heads the Energy & Minerals Section of the Kentucky Geological Survey.
"I think they're trying to prove what's there," said Harris, who has researched the shale.
Fracking involves injecting water — millions of gallons, in some cases — chemicals, and an agent such as sand into boreholes at high pressure to break up rock, freeing oil, gas and natural-gas liquids such as propane and butane locked in tiny pores.
Companies can re-use some of the liquid that flows back up from the hole, but a good deal is wastewater that is typically injected into underground wells, often under pressure.
Wastewater injection has been linked to an increase in earthquakes — called induced seismicity — elsewhere in the country, according to the U.S. Geological Survey.
In one case, such disposal was a contributing factor in a 2011 earthquake in rural Oklahoma that damaged more than a dozen homes and caused a few injuries, according to the agency.
The quake would have caused much more damage in a more densely populated area, the agency said.
Injecting water from oil and gas production into wells can cause earthquakes because it changes the stress on existing faults underground.
The faults are typically at equilibrium because friction counters the push of Earth's plates against them, but the pressure from injecting fluid can alter the balance, Carpenter said.
However, he said the orientation of the fault and other factors have to align for that to happen. Relatively few injection wells in the country have contributed to a fault failing, he said.
"To make these faults fail by injecting fluids, the geologic conditions have to be just right," Carpenter said.
Oil and gas production has not been blamed for any damaging earthquakes in Kentucky. But the state hasn't seen the magnitude of fracking and related wastewater disposal that has ballooned in Texas, Oklahoma and other states in recent years.
Carpenter said it's not likely that fracking or underground injection of wastewater would cause a damaging earthquake in Eastern Kentucky, but he said researchers don't have enough information to rule that out.
Mining and other activities already routinely induce small earthquakes in Kentucky, most of them too small to feel. There will be a greater chance for quakes large enough to be felt as companies inject more waste liquid into the ground, Carpenter said.
The data from the increased seismic monitoring will help researchers differentiate between natural and man-made quakes.
The stations include a very sensitive seismometer and equipment to record data and transmit the information to the KGS office at UK by cellular communication. The units are powered by batteries and have a solar panel to charge the batteries.
The oil industry, an instrumentation maker called Nanometrics Inc., and the UK Department of Earth and Environmental Sciences are participating in the project with the Kentucky Geological Survey.
Carpenter, fellow seismologist Zhenming Wang and Andrew Holcomb, a UK graduate student, have installed four of the units so far this summer, working in the heat to dig holes for a stand to mount the solar panel and electronics and to bury the seismometer.
While the network will help answer one issue related to large-scale fracking, the practice has been controversial for other reasons as well, including concerns about water use, emissions of methane and other pollutants at drill sites, spills or leaks of liquid that contain hazardous chemicals, and heavy truck traffic in rural areas.
The U.S. Environmental Protection Agency said in a study published this month that there have been cases around the country of contamination of wells and water sources because of fracking operations. However, the agency said the number of incidents was small compared to the tens of thousands of wells that have been stimulated with hydraulic fracturing.
The EPA said it found no widespread, systematic harm to water from fracking, though it noted there was a lack of data on some issues, including information needed to compare water quality before and after fracking.
The agency said it could not estimate the frequency of spills at well sites for most states. In the two it could, the estimated number of spills was one per 100 wells in Colorado, but up to 12.2 per 100 in Pennsylvania, the agency said.
Lawrence County Judge-Executive John Osborne said he is concerned about the potential impact on water — including leaks from injection wells — if Rogersville shale production spikes.
"There might not be no good water in Eastern Kentucky," Osborne said. "I have that concern about the future."
State lawmakers approved new rules this year to get ahead of high-volume fracking in Kentucky, requiring water testing near deep horizontal wells; notice to nearby landowners; plans to reclaim well sites; disclosure of the names of chemicals used in fracking; and bonds to cover the cost of plugging and reclaiming wells.
The legislation, which resulted from cooperation between industry, regulators and environmentalists, did not address injection wells or induced seismicity.
However, the group that recommended the changes continues to meet and those issues are part of the discussion, said Andrew V. McNeill, executive director of the Kentucky Oil and Gas Association.
The oil and gas industry contends that hydraulic fracturing is a proven, safe technology that poses no threat to groundwater.
The water and chemicals needed to unlock oil from tight rock formations is typically injected far below the water table.
And Kentucky requires companies to cement steel casings in boreholes to prevent oil or chemicals from escaping into the water table.
Studies have not found significant problems with fracking chemicals leaking from boreholes and contaminating groundwater.
Monte Hay, the fourth generation of his family to be involved in oil and gas exploration in northeast Kentucky, said most operators act responsibly and want to avoid environmental problems, which can be expensive.
"You try to be good stewards of the environment," said Hay, a geologist who operates Hay Exploration Inc. in Ashland.
Lawrence County has been Kentucky's version of the national oil boom. The county did not rank in the top 10 oil producers in the state in 2010, but finished 2014 in front by a wide margin.
Companies pumped 531,676 barrels of oil from beneath Lawrence County last year, more than 10 times the county's 2010 production of 43,105 barrels, according to the Kentucky Department of Revenue. The second-biggest producer in 2014 was Lee County with 307,129 barrels.
The increased activity has helped the local economy, according to officials and businesspeople.
Drilling companies have not hired many local people, but employees and mineral-leasing agents have bought food and gas and helped keep motels full.
The spike in production also has meant a windfall for owners of mineral rights and increased tax revenue for the county.
The state Department for Local Government said the county's share of the state mineral-severance tax went from $150,071 in fiscal year 2013 to $673,563 in fiscal year 2014, which ended last June 30. The county received $512,599 in the first half of the current fiscal year.
As in other parts of the country, however, the drilling boom in Lawrence County has dwindled in recent months because of a drop in oil prices. Companies are still pulling oil from wells put in earlier, but there is little new development.
The jump in production in the county in 2013 and 2014 was from horizontal wells drilled into a layer called the Berea sandstone, which is about 1,500 feet down. It costs far more to put a horizontal well into the much deeper Rogersville shale — $15 million or more.
The fact that companies are still willing to make that investment, even with oil prices so low, is reason for cautious optimism that there will someday be significantly more production and resulting jobs in the area, McNeill said.
The current oil price of about $60 a barrel is not high enough to make it economically feasible to produce deep horizontal wells in the Rogersville, however, Hay said.
And it's still not known if there is enough oil for a significant play, he said.
"It's all a science project now," Hay said. "Will it be commercial? Nobody knows that."