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.

Hydraulic Fracturing‐Induced Seismicity

“…Inset shows cumulative number of earthquakes ( M ≥ 3.0) for this area from the USGS Comprehensive Catalog. Figure modified from Fasola et al (2019).…”

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“…In the mid-continental USA, we use the clusters of HF-IS identified by Yoon et al (2017) from stimulation of the Fayetteville Shale in Arkansas in 2010, where magnitudes reached M 2.9. To these, we add the 2011 sequence from Garvin County, OK, where magnitudes again reached M 2.9 (Holland, 2013); the 2014 sequence from Carter County, OK, where magnitudes reached M 3.2 (Darold et al 2014), and the 2018 M 3.5 sequence near to Karnes City, TX (Fasola et al, 2019). In the Appalachian Basin, we consider the 2013 Harrison County sequence identified by Friberg et al (2014), and the Mahoning County sequence identified by Skoumal et al (2015), both of which were associated with stimulation of the Utica Shale.…”

“…We use the Kolmogorov-Smirnov test, with a 20% significance threshold (Clauset et al, 2009) to determine M MIN , requiring at least 30 events larger than this magnitude. This limits our analysis to the 3 UK Bowland Shale cases; the Crooked Lake clusters 1, 2, 3, and 6 (Bao and Eaton, 2016); Tony Creek (Eaton et al, 2018); the Red Deer ESB02 and ESB10 clusters (Schultz and Wang, 2020); the 2015 Montney sequence described by Babaie Mahani et al (2017); the Septimus sequence described by Peña-Castro et al (2020); Garvin County, OK (Holland, 2013); Karnes City (Fasola et al, 2019); and the Guy-Greenbrier clusters (Yoon et al, 2017).…”

“…While detailed stress information on a site by site basis is often not available, it is of interest to consider the general stress conditions for the different plays and formations identified in Table 1, as revealed by the focal mechanisms of recorded events. The only HF-IS case study from Table 1 which appears to have extensional stress conditions (S hmin < S Hmax < S V , where S hmin , S Hmax , and S V are the minimum horizontal, maximum horizontal, and vertical principal stress components, respectively) was the Karnes case from the Eagle Ford Shale (Fasola et al, 2019). The majority of cases of HF-IS appear to be from sites with strike-slip stress conditions (S hmin < S V < S Hmax ), including the UK Bowland Shale (e.g.…”

“…The largest earthquake in the USA to have been linked to hydraulic fracturing occurred in the Eagle Ford Shale, southwest Texas. Fasola et al (2019) identified 94 earthquakes with M > 2.0 that could be correlated with hydraulic fracturing wells, with the largest having a magnitude of M 3.5 located near to Karnes City. While the primary cause of the Guy-Greenbrier sequence, where the largest event reached M 4.7, is believed to be high-volume wastewater disposal wells (Horton, 2012), Yoon et al (2017) were able to identify clusters of events, with magnitudes below M 3, which appeared to be caused by nearby hydraulic fracturing activities in the Fayetteville Shale.…”