{"id":24208,"date":"2015-06-18T14:50:37","date_gmt":"2015-06-18T19:50:37","guid":{"rendered":"http:\/\/stateimpact.npr.org\/oklahoma\/?p=24208"},"modified":"2015-06-19T13:58:40","modified_gmt":"2015-06-19T18:58:40","slug":"new-research-links-oklahomas-earthquake-surge-to-oil-and-gas-disposal-w","status":"publish","type":"post","link":"https:\/\/stateimpact.npr.org\/oklahoma\/2015\/06\/18\/new-research-links-oklahomas-earthquake-surge-to-oil-and-gas-disposal-w\/","title":{"rendered":"New Research Links Oklahoma Earthquake Surge to Oil and Gas Disposal Wells"},"content":{"rendered":"
\"Oil-field<\/p>\n

Joe Wertz \/ StateImpact Oklahoma<\/p>\n

Oil-field workers lining up a section of pipe at a disposal well plug-back operation in Grant County, Okla.<\/p>\n<\/div>

The vast majority of Oklahoma\u2019s recent earthquakes occurred in areas where the energy industry pumped underground massive amounts of waste fluid byproducts of oil and gas production, scientists write in a new paper published Thursday.<\/p>

<\/p>

Conversely, regions with relatively low amounts of waste fluid injection have experienced comparatively few earthquakes, doctoral student Rall Walsh and geophysics professor Mark Zoback, both of Stanford University, write in \u201cOklahoma\u2019s Recent Earthquakes Linked to Saltwater Disposal<\/a>,\u201d a paper published in the journal Science Advances.<\/i><\/p>

The new research adds to a growing body of scientific evidence<\/a> linking Oklahoma’s earthquake surge to wells used by the oil and gas industry.<\/p>

Briny, chemical-laden waste fluid is a byproduct of oil and gas production. To keep the toxic fluid from contaminating land and sources of drinking water near the surface, energy companies pump it into disposal wells, which trap it deep underground. Once injected, the fluid builds pressure and spreads underground, where it can contact fractured rock formations, \u201cunclamp\u201d faults and release centuries of stored tectonic stress, Zoback says.<\/p>

\u201cThousands of years of earthquakes are occurring in just a few years in Oklahoma due to this massive injection of produced water,\u201d he says.<\/p>

To study how fluid injection correlates to earthquake activity, Walsh and Zoback focused on six regions in Oklahoma: Three areas experiencing a lot of earthquakes, and three adjacent and equally sized areas that are less seismically active.<\/p>

The research shows that the earthquakes are more likely triggered by waste fluid injection than other types of fluid injection, such as enhanced oil recovery<\/a> wells or \u201cwaterflooding<\/a>\u201d operations, where extracted fluid is re-injected underground to pressurize and help push oil to production wells.<\/p>

The three quake-prone regions \u2014 areas near Cherokee, Jones and Perry \u2014 account for 71 percent of Oklahoma\u2019s earthquakes, 27 percent of the state\u2019s total volume of waste fluid disposal, and show a \u201cclear\u201d connection between increased rates of fluid disposal and elevated earthquake occurrence, the research shows.<\/p>

Two of the less seismically active areas, Enid and Oklahoma City, had recorded much less waste fluid disposal. The third of the less seismically active areas, near Ardmore, had \u201cappreciable\u201d levels of fluid injection, but nearly all the injection was into enhanced oil recovery wells, the researchers found.<\/p>

By re-injecting waste fluid into the same formation from which it came, \u201cyou avoid increasing the pressure at depth,\u201d Zoback says. For regulators and the oil industry, the science suggests that oil industry waste fluid might pose less of an earthquake risk if it were re-injected back into the same formation it was pumped out of.<\/p>

Make disposal wells more like enhanced oil recovery wells, basically.<\/p>

\u201cScientifically that\u2019s a solution, but whether it\u2019s practical and economically feasible\u201d is a decision for the oil industry and regulators, Zoback says.<\/p>

The new research also suggests Oklahoma\u2019s earthquake surge has been fueled by the cumulative pressure generated by many waste fluid disposal wells. Most of that fluid is injected into an underground formation known as the Arbuckle, which underlies most of the state.<\/p>

\u201cWhat\u2019s happening is really this regional or large-area response to many wells,\u201d Zoback says. \u201cThe pressure spreads out and the earthquake occurs where the fault is.\u201d<\/p>

The pressure can trigger earthquakes from faults that are miles away from injection wells, this and other research show<\/a>. In some cases, there can be a substantial lag time between fluid injection and the onset of earthquakes, the research suggests.<\/p>

\u201cIt takes a few years for the pressure to spread out in the Arbuckle, find the faults, penetrate to depth, and for the earthquakes to occur,\u201d Zoback says.<\/p>

Wells\u2019 and Zoback\u2019s research also underscores the potential risk of injecting fluid into granite basement rock, which is located just below the popular Arbuckle disposal zone.<\/p>

Oklahoma\u2019s oil and gas regulator has been zeroing in on those potentially risky disposal wells, too. In March, the Corporation Commission ordered the operators of 357 wells to prove they weren\u2019t injecting into basement rock, \u201cplug back\u201d their well to a shallower depth or reduce their waste fluid injection.<\/p>

As of mid-June, 127 wells have been plugged back or are in the process of being plugged back; 86 were proven to not be contacting basement rock; the rest of the wells were inactive or operating with reduced volumes, records from the Corporation Commission show.<\/p>

Most of the earthquakes are small, but many can be felt. Some scientists have linked the 5.7-magnitude quake that struck near Prague, Okla., in November 2011 and injured people to disposal wells. The magnitude and damage caused by the Prague quake gives scientists and officials some indic<\/p>

“It’s more than just a nuisance, it’s a problem that has to be dealt with,” Zoback says.<\/p>

In a separate study published Thursday<\/a> in the journal Science<\/i>, researchers linked an \u201cunprecedented increase\u201d in earthquakes throughout the Central United States \u2014 including Oklahoma, Arkansas, Colorado, Illinois and Texas \u2014 to injection wells. The paper suggests high-rate injection wells \u2014 the ones that pump more than 300,000 barrels per month \u2014 are much more likely to trigger earthquakes than low-rate injection wells.<\/p>\n","protected":false},"excerpt":{"rendered":"

The vast majority of Oklahoma\u2019s recent earthquakes occurred in areas where the energy industry pumped underground massive amounts of waste fluid byproducts of oil and gas production, scientists write in a new paper published Thursday.<\/p>\n","protected":false},"author":36,"featured_media":24002,"comment_status":"open","ping_status":"closed","sticky":false,"template":"","format":"standard","meta":[],"categories":[490],"tags":[489,500,238,419],"acf":[],"_links":{"self":[{"href":"https:\/\/stateimpact.npr.org\/oklahoma\/wp-json\/wp\/v2\/posts\/24208"}],"collection":[{"href":"https:\/\/stateimpact.npr.org\/oklahoma\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/stateimpact.npr.org\/oklahoma\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/stateimpact.npr.org\/oklahoma\/wp-json\/wp\/v2\/users\/36"}],"replies":[{"embeddable":true,"href":"https:\/\/stateimpact.npr.org\/oklahoma\/wp-json\/wp\/v2\/comments?post=24208"}],"version-history":[{"count":10,"href":"https:\/\/stateimpact.npr.org\/oklahoma\/wp-json\/wp\/v2\/posts\/24208\/revisions"}],"predecessor-version":[{"id":24212,"href":"https:\/\/stateimpact.npr.org\/oklahoma\/wp-json\/wp\/v2\/posts\/24208\/revisions\/24212"}],"wp:featuredmedia":[{"embeddable":true,"href":"https:\/\/stateimpact.npr.org\/oklahoma\/wp-json\/wp\/v2\/media\/24002"}],"wp:attachment":[{"href":"https:\/\/stateimpact.npr.org\/oklahoma\/wp-json\/wp\/v2\/media?parent=24208"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/stateimpact.npr.org\/oklahoma\/wp-json\/wp\/v2\/categories?post=24208"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/stateimpact.npr.org\/oklahoma\/wp-json\/wp\/v2\/tags?post=24208"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}