The not so simple relationship between seismicity and oil production in the Permian Basin,west Texas

We have relocated seismicity occurring in the Permian Basin of west Texas between 1975 and 1979 using three-dimensional velocity models constructed from well log information and compared the locations to detailed geological and geophysical models of specific oil fields. The seismicity appears to be related to a variety of causes including migration of naturally occurring overpressured fluids, tectonic activity, reservoir production, and enhanced recovery operations. Many earthquakes may represent a combination of these effects. Although the Permian Basin is the site of numerous oil and gas fields, only a limited number of fields appears to be associated with seismicity. We find that there are similarities in the structural setting in the fields associated with seismicity. Furthermore, fields within the Delaware Basin that are associated with seismicity are located in regions of high vertical and lateral fluid pressure gradients related to an overpressured zone within the Delaware Basin.