Time-resolved model for geothermal engineering in high porosity Slochteren sandstone

Abstract

This work is an extension of the time-resolved poro-elasto-plastic Mohr-Coulomb model by Fokker et al to include a more realistic constitutive model. Experiments on Slochteren sandstone revealed that the inelastic deformation contributes significantly in compressive deformation almost in all stages of loading and instigated the development of a Cam-Clay-like model to reproduce the Slochteren sandstone behavior. This model was adopted for the current extension. A typical behavior of this model is that the presence of a borehole causes both elastic and inelastic deformation everywhere in the reservoir, as opposed to the conventional philosophy with plastic and elastic zones. Our solution handles the spatial and temporal evolution of pressures, permeability, elastic and plastic properties under the assumption of symmetric loading. The applicability of the approach is demonstrated through a number of cases, like fluid injection, shut-in, production, stimulation, and an injection-production sequence.