Prediction of Volumetric Sand Production Using a Coupled Geomechanics- Hydrodynamic Erosion Model

The production of sand grains from an unconsolidated porous solid matrix under viscous fluid flow is inevitable. While sand production has been found to increase effectively well productivity in both heavy oil and conventional light oil reservoir, it can also lead to geomechanical problems. This paper presents a simplified reservoir-geomechanics model in which, oil, fluidized sand and sand phases interact together through mechanical stresses and hydrodynamics within the framework of mixture theory. Sand production mechanisms are reflected from the interaction between geomechanics and an erosion process by which sand grains are detached from the solid matrix due to both fluid and stress gradients. More precisely, the plastic shear deformation of a sand matrix around a well during drilling and pressure drawdown increases the erosion potential. In return, the erosion process also weakens the sand matrix through degradation of its mechanical strength. The self-adjusted mechanism enables the proposed model to predict the volumetric sand production. Both axial and radial viscous flow in a thick wall cylindrical sandstone specimen is computed using the developed model.