Cardott B.J.,Oklahoma Geological Survey
International Journal of Coal Geology
Coal rank, generalized for all coal beds at or near the surface, in the eastern Oklahoma coalfield has been known since 1915. Near the surface (depths <305m, <1000ft), coal rank increases from high volatile bituminous to low volatile bituminous from west to east in the Arkoma Basin in Oklahoma. The rank of subsurface (depths >305m, >1000ft) coals in Arkoma Basin coalbed methane (CBM) prospects was previously unknown. A new Hartshorne coal (Middle Pennsylvanian) rank map is based on mean maximum vitrinite reflectance values of 0.76% to 2.41% Rmax from 70 coal samples from vertical depths of 0 (surface) to 1327m (4355ft). Hartshorne coal rank in the subsurface increases from high-volatile bituminous to semianthracite from west to east in the Arkoma Basin in Oklahoma. Bituminous rank boundaries changed considerably from earlier surface rank maps (primarily by increasing the area of medium volatile bituminous rank coal in the subsurface) and revealed a previously unknown semianthracite rank area. This discrepancy is significant because the rank of deep (>305m, >1000ft) coal resource assessments and CBM exploration projects have been based on shallow coal rank assignments.A total of 2635 Hartshorne (Hartshorne, Lower Hartshorne, and Upper Hartshorne) CBM wells have been completed in Oklahoma since 1988. Most (1610) wells are horizontal with lateral lengths ranging from 4 to 1498. m (14 to 4914. ft; an average of 669. m [2195. ft]). Coal in most Hartshorne CBM wells is medium volatile bituminous rank. Hartshorne coal is semianthracite rank in about 160 CBM wells in Le Flore County. The four Hartshorne CBM wells with the highest initial potential (IP) gas rates (48 to 65 thousand cubic meters per day, Mcmd; 1.7 to 2.3 million cubic feet per day, MMcfd) are medium volatile bituminous rank from horizontal wells in Haskell and Pittsburg counties. IP gas rates < 28.3 Mcmd (< 1 MMcfd) in low volatile bituminous and semianthracite rank Hartshorne horizontal CBM wells may be low due to complications in drilling into high rank coals with cleat spacing < 1. cm, to stimulation differences, or to gas migration into adjacent sandstone channels. © 2011. Source
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PAWNEE, Okla. (AP) — The Latest on the large earthquake in Oklahoma (all times local): Oklahoma Gov. Mary Fallin has declared a state of emergency in Pawnee County after a magnitude 5.6 earthquake struck northwest of Pawnee. The earthquake struck at 7:02 a.m. Saturday and was felt throughout the Midwestern United States, although no severe damage or serious injuries were reported. The quake ties a 2011 earthquake for the strongest earthquake in recorded state history. Fallin's order allows state agencies to make emergency purchases for disaster relief and is the first step toward asking for federal assistance, if necessary. Fallin said in a statement that information is still being gathered and will be reviewed by her coordinating council on seismic activity. The state of emergency lasts for 30 days and additional counties may be added. The Oklahoma Corporation Commission is requiring the shutdown of 37 wastewater disposal wells in the area around the epicenter of a magnitude 5.6 earthquake. The mandate from the commission's Oil and Gas Division comes after the Saturday morning earthquake near Pawnee and includes 514 square miles under commission jurisdiction. Commission spokesman Matt Skinner says another 211 square miles in Osage County is under the jurisdiction of the Environmental Protection Agency. He says the commission is working with the EPA, which will decide what action to take there. Skinner says it isn't known how many wells in Osage County might be affected. The wells will be shut down within 10 days according to a schedule that Skinner says is necessary because seismologists have warned that a large and sudden shutdown of the wells could cause another earthquake. Skinner says the wells were directed to shut down due to scientific links that the increase to the underground disposal of wastewater from oil and gas production induces earthquakes. The commission has previously asked producers to reduce wastewater disposal volumes. The 5.6 magnitude earthquake that struck north-central Oklahoma apparently did not cause significant damage partly because of the type of rock beneath the region. Geophysicist Jefferson Chang with the Oklahoma Geological Survey said a hard, or competent, bedrock crosses north-central Oklahoma while the subsurface around Prague is softer. Chang said the harder rock absorbs more of an earthquake's energy, reducing potential damage. Emergency officials say the Saturday morning quake northwest of Pawnee led to sandstone facings of some buildings falling, but that no buildings collapsed. The quake is the same magnitude and approximately the same depth as a 2011 earthquake near Prague, about 60 miles to the south. In that quake, two towers collapsed at a university in nearby Shawnee. Officials at a nuclear power plant in the southeast corner of Nebraska say tremors from the Oklahoma earthquake were felt at the plant. Nebraska Public Power District's Cooper Nuclear Station south of Brownville declared an "unusual event" just after 7 a.m. because of the minor tremors. Officials say there was no damage to the plant or equipment, and no threat to the public or plant personnel occurred. The plant continued operating Saturday, but station personnel increased monitoring of plant equipment, per the plant's policy. Station emergency preparedness manager Jim Stough says the nuclear station was built to withstand some earthquakes and other scenarios that are likely to occur in the region. Officials say local, county, state, and federal agencies were notified of the event. The Oklahoma Corporation Commission has directed dozens of wastewater disposal wells within an approximate 500-square-mile radius of the epicenter the Oklahoma earthquake to shut down. The commission says about 35 wells are included in the directive, which was issued following the 5.6 magnitude earthquake that struck Saturday morning about nine miles northwest of Pawnee in north-central Oklahoma. The number of magnitude 3.0 or greater earthquakes has skyrocketed in Oklahoma, from a few dozen in 2012 to more than 900 last year. Commission spokesman Matt Skinner says the wells were directed to shut down due to scientific links that the increase to the underground disposal of wastewater from oil and gas production induces earthquakes. The commission has previously asked producers to reduce wastewater disposal volumes. The earthquake ties the record for the strongest earthquake in recorded Oklahoma history. No major damage was reported, and there was one minor injury. One minor injury has been reported as the result of a 5.6 magnitude earthquake in north-central Oklahoma. Pawnee County Emergency Management Director Mark Randell says a man protecting his child suffered a head injury when part of a fireplace fell on him. Randell says the man was treated at a hospital and released. The U.S. Geological Survey reports the quake struck at 7:02 a.m. about nine miles northwest of Pawnee, a town of about 2,200 about 70 miles northeast of Oklahoma City. The USGS also reports about a half-dozen aftershocks in the same area, including one that was a 3.6 magnitude at 7:58 a.m. This update has been corrected to show that the area where the earthquake hit is northeast of Oklahoma City, not northwest. Staffers at the Wolf Creek nuclear power plant in southeast Kansas found no damage to the plant after an earthquake rattled a large swath of the Midwest. Spokeswoman Jenny Hageman says Saturday's 5.6 magnitude earthquake centered in north-central Oklahoma did not shake the plant near Burlington, Kansas, enough to set off a seismic alarm but staff checked it as a precaution. KVOE reports (http://bit.ly/2bKgNRo ) the plant was shut down Friday by a water leak. Hageman says the source of the leak in the reactor cooling system inside the plant's containment area has been identified and that there was never of threat of a radiation leak. It's unclear when Wolf Creek will return to operation. A Pawnee business owner says the 5.6 magnitude earthquake shook his house "like a rubber band" and knocked items off cabinets and broke glass. Furniture store owner Lee Wills told The Associated Press he was awake when the quake struck at 7:02 a.m. Saturday and first thought it was a thunderstorm. But then his home, which is about 2½ miles outside of town, started shaking. Wills said buildings in the downtown area are cracked and sandstone facing on some buildings fell and described the scene as "a mess." The quake was felt as far away as Nebraska. The Pawnee County emergency management director says no injuries have been reported and no buildings have collapsed following a magnitude 5.6 earthquake that ties a 2011 temblor for the strongest in Oklahoma history. Mark Randell said the Saturday morning quake did cause cracks and damages to city buildings, some of which date to the early 1900s. The U.S. Geological Survey reports the quake struck at 7:02 a.m. about nine miles northwest of Pawnee, a town of about 2,200 about 70 miles northeast of Oklahoma City. The U.S.G.S. also reports a 3.6 magnitude aftershock in the same area at 7:58 a.m. This update has been corrected to show that the area where the earthquake hit is northeast of Oklahoma City, not northwest. Oklahoma Gov. Mary Fallin says that crews are checking bridges and structures for damage after the 5.6 magnitude earthquake, which ties a 2011 temblor for the biggest on record in the state. Fallin tweeted Saturday morning that the Oklahoma Department of Transportation is checking bridges in the Pawnee area for damage. The quake was centered about 9 miles northwest of the town of about 2,200 people. Fallin also tweeted that state officials want structural engineers to look at building safety in the wake of the quake, which the U.S. Geological Society happened at 7:02 a.m. No major damage was immediately reported. The quake was felt as far away as Nebraska. An earthquake has rattled a swath of the Great Plains, from Kansas City, Missouri, to central Oklahoma. The United States Geological Survey didn't immediately post data on its website about the size of the earthquake or where it was centered. People in Kansas City, Missouri, Fayetteville, Arkansas, and Norman, Oklahoma, all reported feeling the earthquake at about 7:05 a.m. Saturday.
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The Oklahoma Corporation Commission's new plan about doubles the amount of land covered under a previous plan released in February to help deal with the increase of seismic activity in the state that officials say is caused by oil and natural gas disposal wells. Quakes above magnitude 3.0 now strike the state at a rate of two per day or more, compared with two or so per year prior to 2009. The new plan affects more than 5,000 square miles (12,950 sq km) and more than 400 disposal wells, bringing the combined effect of the two plans to more than 10,000 square miles (28,900 sq km) and more than 600 disposal wells. The new plan that covers central Oklahoma calls for the reduction of wastewater volume by 40 percent below totals from 2014, which equals more than 300,000 barrels of wastewater a day, the commission said. The volume reduction plans will be phased in over two months, with full compliance expected by May 28, the commission said. In 2015, Oklahoma geologists documented strong links between increased seismic activity in the state and the injection into the ground of wastewater from oil and gas production, stating that it is "very likely that the majority of the earthquakes" are triggered by wastewater injection activities tied to the oil and gas industry, according to the Oklahoma Geological Survey. The spike in earthquake activity has put Oklahoma in the center of a national debate over whether wastewater disposal from oil and gas production triggers earthquakes. In response, the commission, and many oil and gas exploration companies, have reduced injection depth and volume in the wells nearest to the seismic activity. Injection wells are used by the oil and gas industry to store wastewater extracted during hydraulic fracturing, or fracking. The water is extracted from the ground along with oil and gas, separated and re-injected into deep wells. The February plan, which covers Oklahoma's northwest region, was after several earthquakes near Fairview in northwest Oklahoma. In the past month, several areas in central Oklahoma experienced earthquakes as well. The expansion also includes 118 disposal wells in the Arbuckle area. Oil and gas operators there must prove the disposal well has not drilled into the basement rock and provide daily and weekly volume reporting.
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The seismic risk maps are used by emergency management officials as well as the country's major engineering and design associations to guide how strong to construct buildings. "By including human-induced events, our assessment of earthquake hazards has significantly increased in parts of the U.S.," Mark Petersen, Chief of the USGS National Seismic Hazard Mapping Project, said in a statement. Some 7 million people in the Central and Eastern United States live or work in areas threatened by so-called induced seismicity, and in parts of these regions, the damage caused by earthquakes could be at parity with that seen in high-hazard regions of California, the USGS said. Oklahoma is at the greatest risk for hazards associated with induced seismicity, the USGS said, followed by Kansas, Texas, Colorado, New Mexico and Arkansas. Oklahoma in 2015 experienced 907 magnitude-3.0 or greater earthquakes, compared with just two of similar size in 2009. In February, a 5.1-magnitude temblor shook the area around Fairview, Oklahoma - the third strongest recorded in the state. The uptick in quakes has prompted serious concern among those near the oil storage hub at Cushing, Oklahoma, home to some 66 million barrels of oil and the delivery point for the West Texas Intermediate futures contract. "We have had some earthquakes that were way to close to those tanks," said Michael Teague, Oklahoma's Secretary of Energy and Environment. The disposal of saltwater - a natural byproduct of oil and gas drilling - into wells has been tied to earthquakes. Oklahoma regulators have already ordered many disposal wells to curb operations. "The good news is that we are already seeing a very positive response to those actions in the form of reduced seismic activity in the central and north central areas of Oklahoma," the Oklahoma Oil & Gas Association said in a statement. Saltwater injections into disposal wells is down by roughly half from a peak of 1.8 million barrels per day in 2014, the Oklahoma Geological Survey said, with half the wells shutting due to low oil prices. The USGS said building code committees are still deciding whether to include induced earthquakes in their revisions, in part because they could be temporary. The American Society of Civil Engineers' 2016 guidelines do not take into account man-made earthquakes and it does not plan to update them until 2022. "There is always a delay in design codes adapting the USGS Seismic Hazard Maps," said Muralee Muraleetharan, a civil engineering professor at the University of Oklahoma.
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"The recent series of strong quakes have spiked public concern and accusations that industry is negligent in disposing of wastewater deep underground." "Two lawsuits in Oklahoma accuse more than a dozen oil and gas companies of triggering recent earthquakes by disposing of their drilling waste in deep wells. The lawsuits filed last week come on the heels of heightened earthquake activity in Oklahoma, where more than 130 this month have registered magnitude 2.5 or higher on the Richter Scale. These events have caused property damage, knocked out the local power supply, and shaken people's faith in the state government's ability to control the situation. "It's pretty intense right now," said Jeremy Boak, a geologist at the Oklahoma Geological Survey. He explained that the state has already experienced seven earthquakes of at least magnitude 4.0 in the past three weeks—about one-quarter the total of such quakes in 2015."