Prior oil and gas production can limit the occurrence of injection-induced seismicity: A case study in the Delaware Basin of western Texas and southeastern New Mexico, USA

Abstract

We demonstrate that pore pressure and stress changes resulting from several decades of oil and gas production significantly affect the likelihood of injection-related induced seismicity. We illustrate this process in the Delaware Basin (western Texas and southeastern New Mexico, USA), in which hydraulic fracturing and waste-water injection have been inducing numerous earthquakes in the southernmost part of the basin where there has been no prior oil and gas production from the formations in which the earthquakes are now occurring. In the seismically quiescent part of the basin, we show that pore-pressure and poroelastic-stress changes associated with prior oil and gas production make induced seismicity less likely. The findings of this study have important implications for the feasibility of large-scale carbon storage in depleted oil and gas reservoirs.

Multivariate statistical appraisal of regional susceptibility to induced seismicity: application to the Permian Basin, SW United States

“…Operational earthquake locations from the TexNet network suggest that most earthquakes occur at near-basement depths of 6-8 km (Savvaidis et al, 2019), although there is a lot of scatter (Figure S1). However, more recent analysis for earthquakes close to the boundary between Reeves and Pecos counties suggest shallower hypocentre depths of 1-3 km depth, consistent with the depths of the Delaware Mountain and Bone Spring Groups (Dvory & Zoback, 2021;Yixiao Sheng et al, 2020). These multi-faceted operations at different depths along with the uncertainty of hypocentre depths mean that without detailed hydrogeological models for specific areas, it is not easy to separate the different factors and their effect on seismicity.…”

“…The correlation coefficient between pre-2013 shallow oil production and post-2017 shallow water injection is 0.88 so we cannot confirm the hypothesis of Dvory & Zoback (2021) that shallow injection into the same formations that were produced from earlier production reduces seismicity rates.…”

“…A LR approach is adopted because of the current number of factors that attributed to causing induced seismicity in the Permian Basin in published work so far (e.g. Dvory & Zoback, 2021;Savvaidis et al, 2020;Skoumal et al, 2020;Tung et al, 2020;Zhai et al, 2021). It can also be seen from Figure 3 that there is no obvious relationship between certain industrial operations and seismicity.…”

“…Using a probabilistic distance-time likelihood association of seismicity with well activity, hydraulic fracturing was also shown by Savvaidis et al (2020) to be one of the main factors causing seismicity in the Delaware basin. Moreover, Dvory & Zoback (2021) showed that pore pressure perturbations from HF could feasibly trigger shallower seismicity in the Delaware Mountain and Bone Spring Groups. Earthquake depths remain highly uncertain in the Permian Basin, so it is difficult to ascertain whether some earthquakes occur within, above, or below, the Wolfcamp Shales.…”

“…Although in Oklahoma near-basement injection clearly induces most seismicity, it remains highly debated as to whether earthquakes in the western Permian Basin are primarily influenced by deep SWD into the Ellenburger Group (Lemons et al, 2019;Skoumal et al, 2020;Tung et al, 2020), HF in the Wolfcamp Group (Savvaidis et al, 2020), shallow SWD into the Delaware Mountain Group (Deng et al, 2020;Zhai et al, 2021), or conventional production of fluids at shallow depth (Deng et al, 2020;Doser et al, 1991Doser et al, , 1992. Moreover, in much of the Permian Basin, there has been production of hydrocarbons from shallow formations, such as the Delaware Mountain Group and Bone Spring Group since the 1970s, which may affect the pre-existing state of stress (Dvory & Zoback, 2021). Hypocentre depths also remain uncertain over the region due to a combined effect of uncertain velocity models and station distribution Skoumal et al, 2020).…”