Full Title: Injection Wells and Earthquakes: Quantifying The Risk
Author(s): Energy In Depth
Publisher(s): Energy In Depth
Publication Date: 11/2015
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According to the U.S. Geological Survey (USGS), approximately 150,000 Class II injection wells are used in connection with oil and natural gas activities across the United States. These include wells for secondary or enhanced recovery (in which wastewater is returned to the reservoir from where it originated to “enhance” the flow of hydrocarbons) as well as disposal wells, where wastewater is disposed in non-producing formations. Roughly 40,000 of these wells are designated for disposal, according to the USGS.
Data from the USGS and several peer-reviewed studies show that out of an estimated 40,000 disposal wells across the United States, only 218 of them have been linked to or even suspected as a possible cause of seismicity. In other words, only 0.15 percent of all Class II injection wells and 0.55 percent of all federally regulated disposal wells in the United States have been tangentially associated with a seismic event of any size. This means that 99.85 percent of all the Class II wells in the United States – and 99.45 percent of all disposal wells in the United States – continue to operate without any issues whatsoever related to seismicity.