Coupled flow and geomechanics modeling of ground deformation and fault stability at the Wilmington Field, CA, 1936-2020

Lluis Salo-Salgado, Josimar A. Silva, Andreas Plesch, John H. Shaw, & Ruben Juanes

Submitted September 7, 2025, SCEC Contribution #14471, 2025 SCEC Annual Meeting Poster #TBD

Improving energy access while mitigating environmental impacts requires the development of subsurface systems at an unprecedented scale. These systems, however, are complex, and hazards such as surface deformation and induced seismicity are difficult to quantify. Wilmington is the largest hydrocarbon field in the Los Angeles Basin; since the 1930’s to today, there has been approximately 2.5 billion barrels of oil produced and ten times as much water injected in the field. Subsidence reached a maximum of 8.8 m in 1965. This history provides a unique opportunity to assess the long-term impacts of reservoir operations on ground deformation and seismic hazard.

Here, we leverage an extensive dataset spanning 85 years of hydrocarbon production at Wilmington to build a coupled model of multiphase flow and geomechanics of the field. Our flow-geomechanics model includes a detailed representation of faults in and around the field, monthly production and injection history, and the effect of permanent (plastic) deformation. First, we assess the impact of initial stress conditions on ground deformation. We show that the background stress controls subsidence and rebound, and that it is not possible to reproduce the deformation history of the field using a purely thrust-faulting stress regime commonly associated with the region. Instead, we find that extensional or strike-slip regimes in the sedimentary section better reproduce the observed ground motions. We then evaluate the evolution of fault stability within and around the main injection interval. Compaction and water injection, in particular, lead to destabilization in faults around and within the main reservoir. This motivates a comparison of the spatial and temporal distribution of seismicity relative to changes in fault stability. These results suggest that subsurface fluid storage in similar settings may destabilize faults, and highlight the need for local stress-state measurements and seismic monitoring protocols.

Key Words
induced seismicity, coupled flow-geomechanics, fault stability

Citation
Salo-Salgado, L., Silva, J. A., Plesch, A., Shaw, J. H., & Juanes, R. (2025, 09). Coupled flow and geomechanics modeling of ground deformation and fault stability at the Wilmington Field, CA, 1936-2020. Poster Presentation at 2025 SCEC Annual Meeting.

Related Projects & Working Groups
Seismology