Exploring the potential linkages between oil‐field brine reinjection, crystalline basement permeability, and triggered seismicity for the Dagger Draw Oil field, southeastern New Mexico, USA, using hydrologic modeling

Abstract

We used hydrologic models to explore the potential linkages between oil‐field brine reinjection and increases in earthquake frequency (up to Md 3.26) in southeastern New Mexico and to assess different injection management scenarios aimed at reducing the risk of triggered seismicity. Our analysis focuses on saline water reinjection into the basal Ellenburger Group beneath the Dagger Draw Oil field, Permian Basin. Increased seismic frequency (>Md 2) began in 2001, 5 years after peak injection, at an average depth of 11 km within the basement 15 km to the west of the reinjection wells. We considered several scenarios including assigning an effective or bulk permeability value to the crystalline basement, including a conductive fault zone surrounded by tighter crystalline basement rocks, and allowing permeability to decay with depth. We initially adopted a 7 m (0.07 MPa) head increase as the threshold for triggered seismicity. Only two scenarios produced excess heads of 7m five years after peak injection. In the first, a hydraulic diffusivity of 0.1 m2 s−1 was assigned to the crystalline basement. In the second, a hydraulic diffusivity of 0.3 m2 s−1 was assigned to a conductive fault zone. If we had considered a wider range of threshold excess heads to be between 1 and 60 m, then the range of acceptable hydraulic diffusivities would have increased (between 0.1–0.01 m2 s−1 and 1–0.1 m2 s−1 for the bulk and fault zone scenarios, respectively). A permeability–depth decay model would have also satisfied the 5‐year time lag criterion. We also tested several injection management scenarios including redistributing injection volumes between various wells and lowering the total volume of injected fluids. Scenarios that reduced computed excess heads by over 50% within the crystalline basement resulted from reducing the total volume of reinjected fluids by a factor of 2 or more.

Induced Seismicity in the Delaware Basin, Texas

“…Map of seismicity near the Permian Basin (green polygon) in western Texas and southeastern New Mexico, including the Dagger Draw (Herzog, ; Zhang et al, ) and Snyder (Davis & Pennington, ; Gan & Frohlich, ) sequences. Epicenters (black crosses) are from the Advanced National Seismic System (ANSS) catalog, New Mexico (Pursley et al, ), and TexNet earthquake catalogs.…”

The Role of Fault‐Zone Architectural Elements on Pore Pressure Propagation and Induced Seismicity

“…The permeability axis assumes a specific storage coefficient of 10 −6 /m. The gray boxes are permeabilities reported by Zhang et al () for the Dagger Draw oil field in southeastern New Mexico (Figure from Zhang et al ).…”

“…The link between wastewater reinjection into basal reservoirs—that is, reservoir formations located directly on top of basement rocks—and triggered seismicity within the underlying crystalline basement has been documented at a number of sites, including Ohio, with injection into the basal Mt. Simon Sandstone (Nicholson and Wesson ; Kim ), New Mexico Permian Basin; with injection into the basal Ellenburger Limestone (Zhang et al ), Oklahoma; with injection into the basal Arbuckle Limestone (Keranen et al , ; Walsh and Zoback , ; Yeck et al ), Texas Fort Worth Basin; with injection into the Ellenburger Limestone (Hornbach et al ), Kansas; with injection into the Arbuckle Limestone (Choy et al ), and Arkansas; with injection into the basal Ozark Aquifer (Horton ). Earthquake hypocenters occur at a wide range of depths (typically 2 to 8 km) below the injection reservoir within the underlying crystalline basement (Table ), sometimes at significant lateral distances (greater than 10 km) from injection wells (Keranen et al ; Zhang et al ).…”

“…Relocation studies of earthquake hypocenters associated with crystalline basement seismicity suggest that fluid migration can occur along conductive sub‐vertical fault zones (e.g., Shapiro et al ; Horton ; Zhang et al ). Faults can act as barriers or conduits to fluid flow (e.g., Antonellini and Aydin ; Caine et al ) or as conduit‐barrier systems (Bense and Person ).…”

“…The failure envelope, which encompassed elevated pressures between 60 and 160 m head (0.6 and 1.6 MPa), extended to 4 km depth after 10 years. Zhang et al (2016) considered fluid migration along a much wider (2 km) conductive (k = 10 −14 to 10 −15 m 2 ) fault zone in their analysis of potential linkages between triggered seismicity (mean hypocenter depth ∼ 11 km) and oil field brine reinjection adjacent to the Dagger Draw oil field in the Permian basin, NM. In that study, elevated fluid pressures (greater than 7 m or 0.07 MPa) extended to depths of greater than 10 km after about 6 years of injection.…”