Seismogenic response to fluid injection in California hydrocarbon basins: The role of permeability structure and implications for crustal stresses

Thomas Gobel, UC Santa Cruz

Wednesday, September 9, 2015 at 10:30 AM

Building 3, Room 3240 (main USGS conference room)
Sarah Minson

The seismogenic response to induced pressure changes provides insight into the proximity to failure of nearby faults. We examined wastewater disposal operations and seismicity throughout the San Joaquin Valley. We developed a method to objectively identify regions with strong correlations between short-term injection rate changes and seismicity. Applying the method to the San Joaquin valley, we find four cases for which short-term injection rate changes are correlated to near-by seismicity. Using a relocated earthquake catalog and a template matching technique to detect small magnitude events, we perform a detailed analysis of geologic setting and pressure diffusion for one of these cases, located at the southern end of the San Joaquin valley. We identify an earthquake swarm with three events above M4 associated with the White Wolf fault (WWF) that followed a rapid increase in wastewater disposal rates. The earthquake activity started within 4 km of a nearby injection well and migrated toward the WWF. Hydrogeological modeling suggests that wastewater disposal likely contributed to seismicity via localized pressure-increase along a seismically active fault between injection-site and WWF. Our analyses shows, that the most acute anthropogenically induced seismic hazard in CA likely stems from injection activity close to active faults, which may result in noticeable seismic activity.

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