Background
Graphic by EPA
Disposal wells take fluids from drilling and fracking and store them deep underground.
Yana Skorobogatov of KUT News researched and reported this article.
What is a Disposal Injection Well?
Injection wells are vertical pipes drilled into deep layers of rock. Natural gas companies use the wells to dispose saltwater waste produced as a result of hydraulic fracturing, or “fracking.” The wells utilize the earth’s soil and bedrock to filter and treat the contaminated water, which is then spread across a wide subsection of the surrounding bedrock for final storage.
Disposal injection, with its cost effectiveness and reportedly low environmental impact, is viewed by many energy companies as the best way to dispose water waste. Other disposal alternatives involve directly discharging treated wastes into receiving waters, or utilizing treated water for irrigation purposes. Both techniques suffer from prohibitive financial and environmental costs, as well as large electric and maintenance requirements. Injection wells, it seems, offer the perfect solution.
Do Disposal Wells Cause Earthquakes?
Disposal wells, however, have failed to provide a panacea for oil-extractors wondering how best to dispose of their dirty byproducts. A recent spate of earthquakes in the Midwest has attracted the attention of many geologists who link the abnormal seismic activity to disposal wells located suspiciously close to the quake epicenters. Quakes in Arkansas, Colorado and Oklahoma, where hard bedrock has a harder time absorbing shock waves emitted during the disposal process, have been tied to injection well activity.
Christopher Joyce, an NPR science correspondent, explains how the use of disposal wells can cause quakes: “The water first used in fracturing rock is retrieved and pumped into these waste wells, which take lots of water. And at more than 9,000 feet deep the water is under high pressure that can build up over months or years. It’s this pressure that can actually create earthquakes.”
Experts attribute the abnormal seismic activity in Oklahoma, where a 5.8-magnitude quake took place on November 5, 2011, to the 181 wells located just miles from the quake’s epicenter. Until two years ago, Oklahoma typically experienced about 50 earthquakes a year, but in 2010, 1,047 quakes shook the state. The explanation, according to the U.S. Army and the U.S. Geological Survey, rests in pressure-breaks from deep-well injections.
Do Earthquakes Linked to Disposal Wells Happen in Texas?
Texas is not immune to the injection well trend. As the nation’s number one oil and gas producer, it’s developed a wastewater disposal system to match. There are more than 50,000 injection wells in Texas servicing more than 216,000 active drilling wells, according the Railroad Commission. Each well uses about 4.5 million gallons of chemical-laced water, according to hydrolicfracturing.com.
Should Texans think of stocking up on earthquake survival kits? Maybe. An October 20, 2011 quake in an otherwise seismically-sound South Texas certainly got people’s attention when it clocked in at 4.8 on the Richter scale. Many experts quickly blamed hydraulic fracking for causing the quake. But a University of Texas seismologist was the first to point out that pumping wastewater into the ground, rather than extracting oil from it, resulted in the sudden eruption in the bedrock. “They [drilling companies] pump the water back into the ground into a deep aquifer to get rid of it,” earthquake researcher Cliff Frohlich at UT’s Institute for Geophysics told KUT News.
