Oklahoma and fracking

Oil output has doubled in the state since the start of 2010, from 160,000 to 320,000 barrels per day, primarily due to fracking for tight oil.

Introduction
Oklahoma is part of the Caney and Woodford Shales, which are sites of drilling and fracking. The state also has thousands of injection and disposal wells, which have been linked to a 5.7 earthquake in the state in 2011.

Drilling wells
Click here for an interactive map of oil and gas wells. In 2009, the state had more than 32,000 oil wells, almost 9 percent of the U.S. total. Continental Resources, the leading tight oil producer in the Williston Basin beneath North Dakota and Montana, revealed in 2012 that its next big target for development is an area southeast of the Cana play it has called the South Central Oklahoma Oil Province (SCOOP).

Shale plays
According to the U.S. Energy Information Administration (EIA), there are three prospective shale plays in the state: the Ardmore, Arkoma and Cana basins, all of which contain parts of the Woodford formation. The Mississippian is also a tight oil formation.

Caney Shale, Oklahoma
The Caney Shale in the Arkoma Basin is the stratigraphic equivalent of the Barnett Shale in the Ft. Worth Basin. The formation has become a gas producer since the large success of the Barnett play.
 * Bill Grieser: Caney Shale, Oklahoma's shale challenge, PDF file, retrieved 25 February 2009.

Woodford Shale, Oklahoma
The Devonian Woodford Shale in Oklahoma is from 50 to 300 feet (15 – 91 m) thick. Although the first gas production was recorded in 1939, by late 2004, there were only 24 Woodford Shale gas wells. By early 2008, there were more than 750 Woodford gas wells. Like many shale gas plays, the Woodford started with vertical wells, then became dominantly a play of horizontal wells. The play is mostly in the Arkoma Basin of southeast Oklahoma, but some drilling has extended the play west into the Anadarko Basin and south into the Ardmore Basin. The largest gas producer from the Woodford is Newfield Exploration; other operators include Devon Energy, Chesapeake Energy, Cimarex Energy, Antero Resources, St. Mary Land and Exploration, XTO Energy, Pablo Energy, Petroquest Energy, Continental Resources, and Range Resources. Production from the Woodford Shale has peaked and is now in decline, however.
 * Oklahoma Geological Survey: Map of Woodford shale wells, accessed 25 February 2009.
 * Brian J. Cardott: Overview of Woodford gas-shale play in Oklahoma, 2008 update, PDF file, retrieved 25 February 2009.

Disposal wells
Click here for an interactive map of disposal wells.

As of 2012, there are an estimated 11,000 private and commercial injection and disposal wells in Oklahoma. Each year those wells are injected with billions of gallons of oil and gas wastewater, according to the Oklahoma Corporation Commission -- 8.8 billion gallons of wastewater in the last two years. The Corporation Commission says they have not tallied the amount of water injected through private wells.

Earthquakes
Oklahoma has seen a sharp rise in the number of earthquakes in the last few years. In August 2011, the Oklahoma Geological Survey examined a cluster of earthquakes in Oklahoma and found "that shortly after hydraulic fracturing began small earthquakes started occurring, and more than 50 were identified, of which 43 were large enough to be located. Most of these earthquakes occurred within a 24 hour period after hydraulic fracturing operations had ceased."

On April 18, 2012, University of Memphis scientist Stephen Horton released his findings that a 5.7 quake in November 2011 was "possibly triggered" by injection wells near the fault that ruptured. Horton found that 63 percent of earthquakes have occurred within 10 kilometers (about 6 miles) of a deep injection well, compared to a 31 percent chance of a random, natural earthquake happening within 10 kilometers of a deep injection well. He did note that the correlation between the location of the quake centers and the wells was complicated by the fact that some of the nearby injection wells had been in operation for 10 years, and the amount of fluid being injected has reportedly been on the decline for the last five years.

In July 2012 it was reported that Oklahoma officials ignored advice about injecting water into faults, to maintain production of oil and natural gas.

A 2013 study published in Geology linked Oklahoma's 5.7 earthquake to underground injection of wastewater, saying a decades-long time lag between injection and tremors is possible. Geologists placed seismometers in the area after the initial quake and were able to track fault rupture areas, which showed close proximity to disposal wells. According to the researchers: "we interpret that a net fluid volume increase after 18 yr of injection lowered effective stress on reservoir-bounding faults. Significantly, this case indicates that decades-long lags between the commencement of fluid injection and the onset of induced earthquakes are possible."

In October 2013 a drilling wastewater operator ceased injections at Oklahoma's Love County Disposal Well after a series of earthquakes. Injection began Sept. 3 and the earthquakes started Sept. 17 in the area near the Texas border, about 100 miles north of Dallas. The strongest was magnitude 3.4.

Spills and accidents
Click here for an interactive map of spills, leaks, and other drilling incidents.

A 2009 and 2010 report from the EPA Water Quality Protection Division lists concerns the agency has with the state's injection well program, including inaccurately reported data and operators injecting for years without valid permits. Ultimately the report recommends the Corporation Commission in Oklahoma take immediate actions to fix "critical problems."

Worker deaths and injuries
Between October and June 2012, the U.S. Occupational Safety and Health Administration (OSHA) Oklahoma City reported nine work-related deaths in the oil/gas industries and three people who were injured in a drilling rig fire. In response, OSHA, the state Department of Labor, and the Mid-Continent Exploration & Safety Production Network asked Oklahoma’s oil and gas exploration and production companies to stand down and stop operations for a meeting on safety issues.

Legislative issues and regulations
In July 2011 the Oklahoma Corporation Commission was established to regulate hydraulic fracturing of oil and gas wells as a well completion operation. The Commission’s environmental protection rules were set up to address various aspects of well completion, and compliance with the rules is assured through inspection, reporting, investigation, and enforcement mechanisms.

Chemical disclosure
In May 2012 it was voted that Oklahoma oil and natural gas producers would to forced to disclose the chemicals used in their hydraulic fracturing operations under new rules set to go into effect July 1, 2012. Oklahoma Governor Mary Fallin signed off on the rules, which were approved by the Oklahoma Corporation Commission. Companies will report directly to the commission or use FracFocus.org.

As of January 2014, operators of all oil and gas wells in the state must report the chemicals used in hydraulic fracturing either directly to the website FracFocus.org or to the Oklahoma Corporation Commission, which will add the information to the FracFocus database.

Federal lands
In September 2013 it was reported that the Oklahoman government would join Alabama, Montana and Alaska in protesting Bureau of Land Management plans to regulate hydraulic fracturing on federal land.

Fracking and earthquakes
A 2011 United States Geological Survey (USGS) report, Examination of Possibly Induced Seismicity from Hydraulic Fracturing in the Eola Field, Garvin County, Oklahoma," links a series of earthquakes in Oklahoma in January 2011 to a fracking operation underway there. The USGS found that, overall, some 50 small earthquakes had been registered in the region, ranging in magnitude from 1.0 to 2.8. The bulk occurred within 2.1 miles of Eola Field, a fracking operation in southern Garvin County. The USGS determined that "the character of the seismic recordings indicate that they are both shallow and unique.”

Related SourceWatch articles

 * United States and fracking

Click on the map below for state-by-state information on fracking: