Permian Basin Earthquakes Rattling Up a Mess of Trouble in Texas

Abstract

_ Few sounds in the American Southwest make the heart race like a rattlesnake’s warning. But lately it’s the rattle of glass windows and grandma’s dishes making hearts skip a beat across the Permian Basin as these tattletale signs indicate an earthquake is slithering through the subsurface. Two of the five largest earthquakes in Texas history—a magnitude (M) 5.4 on 16 November and a M 5.2 on 16 December—occurred in the Permian during the fourth quarter of 2022. In the 30 days following the December temblor, there were more than 230 lower-magnitude seismic events across the basin recorded by TexNet, the Texas state earthquake monitoring network managed by the Bureau of Economic Geology (BEG) at The University of Texas at Austin (UT). In 2017—the first year that TexNet began data collection—there were 46 M ≥2.5 earthquakes recorded in the Permian’s Delaware Basin and 26 in the Midland Basin. In 2022, there were 634 and 72 earthquakes recorded, respectively. This increase in the number of seismic events is troubling as the Permian is the nation’s leading oil and gas production basin. Roughly shaped like a butterfly—with the left wing the Delaware Basin, its body the Central Basin Platform, and the right wing the Midland Basin—the Permian Basin spans more than 75,000 square miles, with the breadth of the historic basin’s century of hydrocarbon production as equally wide. The first commercial oil well was completed in 1921, with oil production continuing through the decades before peaking at nearly 2 million B/D and natural gas production reaching almost 10 Bcf/D in the 1970s. The combination of directional drilling and hydraulic fracturing, along with the application of new technologies, returned the Permian to its perch as the nation’s top producer after many years of production declines. In 2022 the Permian accounted for more than 43% of all oil produced in the US, according to the Federal Reserve Bank of Dallas. December’s oil production surpassed 5.5 million B/D and natural gas exceeded 21 MMcf/D, the US Energy Information Administration reported. While Prosperity returned to the Permian, she did so with considerable produced water baggage that the industry and its regulators are working to address as the complexities of the basin’s geology are rattling dishes and nerves. Slippery When Wet Thirty billion barrels or 1.3 trillion gallons: that’s the volume of produced water disposed underground in the Permian over the past 10 years, according to Rob Bruant, director of product and research at B3 Insight. It’s the equivalent of 2 million Olympic-sized swimming pools. Therein lies the irony of the Permian’s expansive growth. For every 1 bbl of oil produced from formations so impermeable that explosive charges and sand are needed to open and prop up pathways for fluid to flow, there are anywhere from 2 to 15 bbl of brackish and saline formation water produced, requiring proper management and disposal by the operator. Historically, the most common way of managing this produced water was through disposal into EPA Class II injection wells. It was estimated in 2012 that 99% of produced water in Texas was managed through injection, either for disposal or enhanced oil recovery, according to a Groundwater Protection Council report, with about 53%, or 5.3 billion bbl, disposed that year.