Volume 52

Numerical Simulation of Pore-Scale Supercritical CO₂ Enhanced Oil Recovery Based on Tight Sandstone Core Bingtao Yang, Pingchuan Dong

Abstract

Carbon capture, utilization and storage (CCUS) is an important way to deal with the global climate crisis. In recent years, the geological storage of carbon dioxide has been extensively studied from micro to macro. In order to understand the percolation law of CO₂ geologic storage and EOR from the microscopic point of view, the numerical simulation of two-phase flow in conventional sandstone cores during supercritical CO₂ EOR was carried out. The two-dimensional pore structure of tight sandstone was characterized by field emission scanning electron microscopy (FE-SEM), and a two-dimensional flow model was constructed by combining Tyson polygon. The Phase field method was used to simulate the oil and gas phase flow in the process of supercritical CO₂ enhanced oil recovery. The distribution of CO₂ under different initial pressure gradients, rock wettability and viscosity ratio and the changes of oil phase saturation were compared, and the mechanism of CO₂ reservoir and percolation under the micro-three-dimensional pore scale was revealed. The results show that : (1) With the increase of the initial pressure gradient of the two phases, the fingering effect is enhanced, the spread range is reduced, the gas invasion possibility is increased, and it is possible to break through the fingering effect and realize multiple dominant channels in parallel; (2)With the increase of rock’s CO₂ wettability, the spread range of CO₂ expands and the storage of CO₂ increase-es;(3)As the viscosity ratio of two phases decreases gradually, the flow resistance between fluids decreases, and the gas phase seepage capacity increases. In summary, the two-phase flow numerical simulation of CO₂ EOR based on a two-dimensional model reveals the seepage mechanism in the process of CO₂ EOR in a higher dimension, providing theoretical guidance and technical support for the study of CO₂ EOR and CO₂ geological reservoir.

Keywords COâ‚‚ Enhanced Oil Recovery , FE-SEM , Pore-Scale , Phase Field Method ,Numerical Simulation