Framing the Reservoir: Impact of Area of influence, Boundary Pore Volume and Transmissibility on CCS Simulations

Reducing GHG, especially CO2, is essential for addressing global climate change. Carbon capture and storage (CCS) is a leading, practical and scalable strategy, with deep saline aquifers offering significant potential. Numerical modelling is used to assess storage potential, particularly the extent of pressure and saturation plumes, necessary for forecasting regulatory compliance, risk management, and addressing potential liabilities associated with legacy wells. Modelling also evaluates geomechanical stability, and potential impacts on underground sources of drinking water. Due to computational limits, simulations need to focus on smaller subregions of the reservoir.

We use synthetic models to study how to reduce the size of extended reservoirs and to frame the dynamic model with specific boundary conditions. We consider the behaviour of the bottom hole pressure at the injector well and its behaviour with the pore volume multiplier of boundary cells and the consequent transmissibility. We study the influence of the whole reservoir size, whether limited or boundless, and of the permeability and injectivity. We first present the theory on a small base 1D model. We then push the limit on an extensive model and for various permeabilities. Finally, we propose an effective solution to accurately frame any reservoir model with specific boundary conditions.