Fracking and Earthquakes in Oklahoma: An Analysis of the Linkages

Over the last twenty years the number of earthquakes in the State of Oklahoma has increased significantly. This study investigates the relationship between hydraulic fracturing wastewater injection wells and the increase in seismicity. In this work SPSS (Statistical Program for Social Sciences) was used to analyze all the data for correlations between wastewater well injection volumes. And psi (pounds per square inch), and earthquakes. SPSS was also used to examine the relationship between the injection of wastewater and the time-delay of seismicity. ArcGIS 10.3.1 (Geographic Information System) was used to explore the density of earthquakes and their distance from wastewater injection wells. This study finds that there is a relationship between wastewater injection volume, distance and time-delay of the injections and earthquakes. Pore pressure was not found to be a contributor to seismicity. However, the depth of the wastewater wells, which was not one of the variables in this study, showed a positive correlation to the increase in earthquakes in Oklahoma. This study reveals some important practical suggestions for the wastewater disposal industry. By setting up industry standards, such as, keeping volume below 150,000 barrels/month, and shortening well depth to at least 1km from the Precambrian crystalline basement the wastewater disposal industry could be more confident that they are lowering their risk of inducing earthquakes and thereby reducing their risk of insurance liability claims and litigation.