Abstract
Long-term production of gas from the Groningen field has led to subsidence and seismicity in the region. Most of the prior Groningen modeling studies assumed elastic deformation of the reservoir due to the challenges in modeling poroplasticity in a reservoir with hundreds of faults and decades of production history. Here we quantify the role of inelastic deformation in production-induced subsidence and seismicity in the field via 3D high-resolution multiphysics modeling which couples multiphase flow and elastoplastic deformation in a complex geologic system made of claystone overburden, carboniferous underburden, and the gas-bearing sandstone reservoir compartmentalized with 100+ faults. We drive the model with four decades of historical production, spanning the period of induced seismicity, and two decades of future production under gas injection-enhanced recovery. We calibrate the model using the available pressure and subsidence data and analyze compartmentalized depletion and deformation due to spatially varying production and fault distribution. We analyze stress and strain in the caprock-reservoir depth interval to elucidate the role of inelasticity. We use the evolution in shear and normal tractions on seismogenic faults that hosted 1991-2012 seismicity to quantify the evolution in Coulomb stress and geomechanical stability of the faults.
