High Resolution Simulations with a Compositional Parallel Simulator for History Matching Laboratory CO²/Brine Core Flood Experiment

Numerical simulators are essential tools to develop a better understanding of the geologic characteristics of brine reservoirs and to build support for future CO₂ storage projects. Modeling CO₂ injection requires the implementation of multiphase flow and an equation of state to compute the dissolution of CO₂ in brine and vice versa. Capillary pressure and relative permeability need to be consistent with permeability/porosity variations. It is, therefore, crucial to gain confidence in the results of numerical simulators by validating the models and numerical accuracies using lab and field pilot scale results. A published steady state core scale CO₂/brine displacement results was selected for our numerical study. The experimental results accompanied by fluid properties, relative permeability and capillary pressure curves, and medical X-ray CT images of subcore porosity, CO₂ saturation CT images, and gas saturation histogram. Published saturation measurements provided insight into the role of heterogeneity in final CO₂ distribution where slight variation in porosity gives rise to large variation in CO₂ saturation distribution.

High resolution compositional simulations of brine displacement with supercritical CO₂ are presented using IPARS (parallel compositional reservoir simulator). 3D numerical model of the Berea core was constructed using geostatistical based permeability and porosity distributions. Grid cells were on the order of 1 mm x 1 mm x 6 mm with a total of 32000 cells. The core was initially saturated with brine before the injection of supercritical CO₂.Fluid properties were calibrated against the measured data. Capillary pressure and relative permeability curves were based on the measurement with capillary pressure scaling based on Leverett J-function for permeability, porosity, and interfacial tension for every grid element. Simulation results indicated that accurate representation of capillary pressure at small scales was critical. Water drying and the shift in relative permeability had significant impact on final CO₂ distribution along the core.