Earthquakes linked to oil and gas activity are in the news. A recent study in Ohio linked a rash of small earthquakes to fracing of wells in the area. Earthquakes in Oklahoma have increased tenfold since 2009. A swarm of small earthquakes hit the Dallas-Fort Worth area recently. The US Geological Survey is raising its evaluation of earthquake hazard risk in Texas as a result.
In Texas, the spate of small earthquakes is tentatively tied to injection wells rather than fracing of new wells. The theory is that the injected water lubricates lithologic layers, allowing them to slip and causing quakes.
The Environmental Protection Agency estimates that there are 144,000 Class II injection wells in the US. The RRC has permitted more than 50,000 Class II injection wells in Texas since the 1930’s. These injection wells are used to dispose of water and waste produced from wells, both that from the fracing process and water produced with oil and gas in the production phase. Many oil wells produce hundreds of barrels of water for each barrel of oil produced. Without injection wells, the Texas oil and gas industry would screech to a halt.
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