3D geomechanical modeling of induced seismic slips considering realistic
reservoir geometry with intersecting faults
Abstract
Geomechanical simulations of induced seismicity generally involve a
simple reservoir geometry in terms of reservoir structure and fault
distribution. Because the depletion of the reservoir controls the
incremental stress field, the geometry of the reservoir has a
substantial influence on the occurrence of induced earthquakes. We
develop geomechanical models based on a realistic geological model of
the reservoir in the Groningen gas field. The model captures the main
characteristics of the reservoir structures in the Zeerijp region.
Through quasi-static and dynamic simulations, we observe that a smaller
intersection angle between the two normal faults in the Zeerijp region
causes an increase in the incremental Coulomb stress at the lower
reservoir juxtaposition adjacent to the intersection. As a result, this
intersection angle strongly affects the location of the initial seismic
slip, the rupture pattern, and the location of the maximum slip. Our
simulation produces an earthquake of magnitude MW 3.0, due to fault
reactivation occurring at a reservoir depletion value of 26 MPa. These
values are similar to those for the Zeerijp 2018 earthquake of ML 3.4.
The location of the simulated rupture is close to the inverted
hypocenter location for the 2018 earthquake. Our results suggest that it
is crucial to incorporate realistic reservoir structures when simulating
induced seismicity in a specific region.