Experimental and Numerical Simulation Study on Single Layer Injectivity for CO2 Flooding in Low Permeability Oil Reservoir

Abstract

Abstract Supercritical carbon dioxide can keep miscible with crude oil, and eliminating the two-face interface existed in conventional water and gas flooding. The displacement efficiency in laboratory experiment is nearly 100%, so it has the potential to increase oil recovery significantly. However, in practical application of CO2 miscible flooding, severe disaccord appears with injection time increasing between the single layer’s injectivity and its physical property because of many influencing factors, the injection ratio of high permeable layers increases, and the injection ratio of low permeable layers decreases, the injectivity of single layers is unbalanced seriously, so the CO2 swept volume will be influenced, finally leading to the poor EOR result. According to the laboratory experiment of parallel connection cores, injection and production profile in practice and the prediction of numerical reservoir simulation, getting the conclusion that the main influencing factors for the injectivity of single layer are interlayer heterogeneity, mobility ratio, gravity, CO2 molecular diffusion and capillary force, and interlayer heterogeneity influences injectivity most seriously. For avoiding the injectivity disaccord, based on these influenced factors, suggestions have been offered to the CO2 miscible flooding pilot test in Jilin oilfield, these suggestions can provide reliable methods for enlarge CO2 flooding swept volume.