Abstract
Abstract The Delaware basin of west Texas and southeast New Mexico has experienced elevated earthquake rates linked spatiotemporally to unconventional petroleum operations. Limited knowledge of subsurface faults, the in situ geomechanical state, and the exact way in which petroleum operations have affected pore pressure (Pp) and stress state at depth makes causative assessment difficult, and the actions required for mitigation uncertain. To advance both goals, we integrate comprehensive regional fault interpretations, deterministic fault-slip potential (DFSP), and multiple earthquake catalogs to assess specifically how faults of two systems—deeper basement-rooted (BR) and shallow normal (SN)—can be made to slip as Pp is elevated. In their natural state, the overall population faults in both the systems have relatively stable DFSP, which explains the low earthquake rate prior to human inducement. BR faults with naturally unstable DFSP and associated earthquake sequences are few but include the Culberson–Mentone earthquake zone, which is near areas of wastewater injection into strata above basement. As a system, the SN faults in the southcentral Delaware basin are uniformly susceptible to slip with small increases in Pp. Many earthquakes sequences have occurred along these shallow faults in association with elevated Pp from shallow wastewater injection and hydraulic fracturing. Our new maps and methods can be used to better plan and regulate petroleum operations to avoid fault rupture.
Highlights
The Delaware basin of West Texas and Southeast New Mexico is one of the world’s most productive petroleum basins (Fig. 1)
The deterministic fault-slip potential (DFSP) map we provide should be used to assess the faultture of exclusively deep faults, it is the shallow normal (SN) faults in direct com- slip hazard related to petroleum operations in the Delaware munication with ΔPp that host most of the earthquakes in the basin region and as a general guide for mitigation
BR faults that are potentially unstable exist throughout the Delaware basin region, but only a few earthquake sequences are associated with these faults, most prominently the Culberson–Mentone earthquake zone
Summary
The Delaware basin of West Texas and Southeast New Mexico is one of the world’s most productive petroleum basins (Fig. 1). Dvory and Zoback (2021b) provide a smoothed and interpolated stress field (Fig. 1) that closely fits the discrete stress observations We use this interpolation for our DFSP analysis and assume an intermediate Aφ value between the Delaware basin and the Central basin platform of 0.7. The great majority of recent earthquakes do not occur on BR faults, but on northwest-trending shallower normal (SN) faults in the central Delaware basin that do not extend to the depth of the BR faults Our interpretation of these seismogenic faults is newly presented here and based on integrating 3D reflection seismic data (extending the work of Charzynski et al 2019; Cook et al, 2019), unpublished records from Railroad Commission of Texas, and as directly reported to us by petroleum operators (Fig. 2a). The SN faults, which are uniformly unstable, spatially correlate to many earthquake sequences in the central Delaware basin
Sign-in/Register to view highlights & summary Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
