Pressure Jump Stabilization for Compositional Poromechanics on Unstructured Meshes

Abstract

While commonly used in practice for large-scale simulation of coupled subsurface flow and displacement, discretizations in which the solid matrix displacement is represented using linear, nodal elements and flow variables are represented as piecewise constants over each cell are not inherently inf-sup stable. This means that when undrained and incompressible conditions are approached, spurious pressure oscillations will appear in the numerical solution. This is particularly relevant in simulations of carbon sequestration, where the caprock above the injection location should be nearly impermeable. In this work we extend the idea of pressure jump stabilization to the compositional poromechanics setting in order to suppress these spurious oscillations. We apply this method to simulations of CO2 injection into a synthetic aquifer which is represented using a fully unstructured mesh. The results show that the stabilization is effective at smoothing the pressure field without adversely affecting the prediction quality of other quantities of interest.