A new study led by researchers at The University of Texas at Austin has found that the majority of earthquakes in the Delaware Basin, a prolific oil-producing region in West Texas and New Mexico, can be linked to oil and gas production.
The study, published in Seismological Research Letters, analyzed data from 2017 to 2020 and found that 68% of earthquakes above magnitude 1.5 were highly associated with one or more of the following oil and gas production activities: hydraulic fracturing or the disposal of produced formation water into shallow or deep geologic formations. These activities are known to increase subsurface pore pressure, which can trigger earthquakes.
The researchers used a combination of statistical analysis and physics-based modeling to disentangle the connection between earthquakes and oil and gas activities. The model divided the Delaware Basin region into a grid of five kilometer squares (about 3 miles) and analyzed the connection between seismicity, oil and gas activity, and subsurface pore pressure for each square over time.
The study found that 43% of earthquakes above magnitude 1.5 were linked with injection into shallow sedimentary formations, above the hydraulic fracturing depth; 12% were linked with injection into deep sedimentary formations above the basement rock and below the hydraulic fracturing depth. Hydraulic fracturing was linked to only 13% of earthquakes, but this was higher than previously expected.
The 2020 magnitude 5.0 earthquake that occurred in Mentone, Texas happened in a region where seismicity was strongly associated with deep produced water injection.
The study’s lead author, Iason Grigoratos, said that the model is applicable to other regions experiencing seismicity linked to subsurface fluid injection operations. He added that the findings could help oil and gas producers and regulators identify potential risks and adjust production and disposal activity to decrease them.
The study was funded by the State of Texas through the TexNet program. Ellen Rathje, a professor at the UT Cockrell School of Engineering, is also a study co-author.