Streamline-Based Simulation of Carbon Dioxide Sequestration in Saline Aquifers

Abstract: Subsurface sequestration of CO2 has received attention from the global scientific community in response to climate change concerns due to higher concentrations of CO2 in the atmosphere. Mathematical models have thus been developed to aid the understanding of multiphase flow of CO2 and trapping mechanisms during subsurface sequestration. Solutions to these models have ranged from analytical, semi-analytical and numerical methods, each having its merits and limitations in terms of underlying physics, computational speed and accuracy. We present a streamline-based method for modeling CO2 transport in saline aquifers which leverages sub-grid resolution capabilities of streamlines in capturing small- and large-scale heterogeneity effects during CO2 injection. Our approach is based on an iterative IMPES scheme and accounts for the physical processes characteristic of CO2 injection in saline aquifers. These include compressibility, gravity, capillarity, mutual solubility, precipitation and formation dry-out effects. Our streamline simulation method provides an extension of previous streamline-based models through rigorous treatment of transverse fluxes arising from compressibility, gravity and capillary effects. We present series of examples encompassing different levels of geologic and geometrical complexity to illustrate the relevance, accuracy and computational efficiency of the approach.