Hydraulic Fracture Injection Strategy Influences the Probability of Earthquakes in the Eagle Ford Shale Play of South Texas

Abstract

Seismicity in the Eagle Ford play grew to 33 times the background rate in 2018. We identified how hydraulic fracturing (HF) contributed to seismicity since 2014 by comparing times and locations of HF with a catalog of seismicity extended with template matching. We found 94 ML ≥ 2.0 earthquakes spatiotemporally correlated to 211 HF well laterals. Injected volume and number of laterals on a pad influence the probability of seismicity, but effective injection rate has the strongest effect. Simultaneous stimulation of multiple laterals tripled the probability of seismicity relative to a single, isolated lateral. The 1 May 2018 MW 4.0 earthquake may have been the largest HF-induced earthquake in the United States. It occurred ~10 km from a MW 4.8 earthquake in 2011 and was thought to be induced by fluid extraction. Thus, faults in this area are capable of producing felt and potentially damaging earthquakes due to operational activities.