Geologic influence on induced seismicity: Constraints from potential field data in Oklahoma

Abstract

Recent Oklahoma seismicity shows a regional correlation with increased wastewater injection activity, but local variations suggest that some areas are more likely to exhibit induced seismicity than others. We combine geophysical and drill hole data to map subsurface geologic features in the crystalline basement, where most earthquakes are occurring, and examine probable contributing factors. We find that most earthquakes are located where the crystalline basement is likely composed of fractured intrusive or metamorphic rock. Areas with extrusive rock or thick (>4 km) sedimentary cover exhibit little seismicity, even in high injection rate areas, similar to deep sedimentary basins in Michigan and western North Dakota. These differences in seismicity may be due to variations in permeability structure: within intrusive rocks, fluids can become narrowly focused in fractures and faults, causing an increase in local pore fluid pressure, whereas more distributed pore space in sedimentary and extrusive rocks may relax pore fluid pressure.

Aeromagnetic Data Reveal Potential Seismogenic Basement Faults in the Induced Seismicity Setting of Oklahoma

“…Corresponding magnetic gradients highlight linear features that in some areas correspond to major mapped faults (Jones & Lyons, 1964;Luza & Lawson, 1982;Shah & Keller, 2017). Combining these data gravity and drill data reveals a relation between seismicity and interpreted lithology, where most earthquakes appear to occur in fractured intrusive rocks (Shah & Keller, 2017), especially the central Oklahoma granite and Spavinaw granite groups described by Denison (1981) and areas in northwestern Oklahoma believed to contain intrusive rocks associated with the midcontinent rift. There is also a lack of seismicity in areas marked by intrusions associated with relatively smooth magnetic anomalies such as the Cleveland magnetic anomaly ( Figure S1), attributed to a lack of major faults that might serve as fluid pathways.…”

Reservoir Structure and Wastewater‐Induced Seismicity at the Val d'Agri Oilfield (Italy) Shown by Three‐Dimensional Vp and Vp/Vs Local Earthquake Tomography

“…As observed in the CM2‐linked earthquakes, migration fronts of injection‐induced seismicity show commonly a dominant updip component coherently with the migration attitude of pressurized fluids along preferential pathways (Cox, ). Nevertheless, downward migration of seismicity and deep sequences in the basement rocks have been reported and related to the strong hydrological control exerted by deep seated large faults that promote pressure channeling effects under the injection formations (Chang & Segall, ; Goebel et al, ; Keranen et al, ; McNamara et al, ; Shah & Keller, ). Seismicity linked to well CM2 has a cutoff depth of 4.5–5.0 km (Figures a, b, and ).…”

“…Pore fluid pressure changes induced by high‐rate disposal wells can trigger noticeable seismicity at great distances (> 10 km) from injection sites (Yeck et al, ) and at significantly greater depths than those of the formations where fluids are disposed (Horton, ; Keranen et al, ). In such cases, high permeable fault zones play a key role in triggering large earthquakes because they can transmit pore pressure perturbations and channel fluid flow over large distances from high‐rate wells to critically stressed basement faults (Shah & Keller, , and references therein). Therefore, a better understanding of the reservoir where fluids are injected and the identification of structures that may channel pore pressure diffusion and fluid migration toward large active faults are fundamental issues for a safe management of disposal activity.…”

The Geological Susceptibility of Induced Earthquakes in the Duvernay Play

“…However, in some cases, geological proxies (e.g., Eaton, 2017;Schultz et al, 2016;Shah & Keller, 2016;Brudzinski et al, 2016) have been successfully used to provide first-order explanations of potential induced seismicity locations. However, in some cases, geological proxies (e.g., Eaton, 2017;Schultz et al, 2016;Shah & Keller, 2016;Brudzinski et al, 2016) have been successfully used to provide first-order explanations of potential induced seismicity locations.…”