Is Two-Way Coupled Geomechanical Modeling Essential for CO2 Storage in Deformable Chalk Reservoirs?

Abstract

This study investigates the benefits of employing two-way coupling simulations over one-way coupling across four stages: gas production, shut-in, CO2 injection, and post-injection. In two-way coupling, dynamic updates to porosity and permeability are captured by iteratively linking a reservoir flow simulator (Intersect) with a geomechanics simulator (Visage), providing more accurate predictions of subsurface behavior. Our results demonstrate that two-way coupling is crucial for accurately modeling platform displacement, pore pressure changes, and caprock integrity, particularly in response to the thermal effects of CO2 injection, which contracts the pore/rock structure and the fluid inside simultaneously. One-way coupling, by contrast, introduces errors by neglecting real-time feedback between mechanical stresses and fluid flow.

The findings underscore the necessity of using fully coupled simulations in CO2 storage projects, particularly for assessing caprock integrity and ensuring long-term storage security. This work offers valuable insights into optimizing THM models for CO2 injection in chalk formations and contributes to the ongoing efforts to develop safe, reliable CO2 storage solutions.

Keywords: THM; deformation, rock contraction, fluid contraction, coupled simulations