Effects of the errors between core heterogeneity and the simplified models on numerical modeling of CO2/water core flooding

Abstract Core heterogeneity is an important factor influencing CO2 and brine migration in porous media but difficult to be accurately described using models. In this study, we quantitatively evaluate the effects of the errors between core heterogeneity and the simplified models on numerical modeling of CO2 core flooding. Results indicate: 1) The model error from the 1D simplification of 3D petrophysical heterogeneity could make the multiphase flow modeling fail to reflect the mean behavior of the core plug, and the resultant deviations in the averaged CO2 saturation (SCO2) can span from -0.1 to 0.2. Besides, using the 1D heterogeneous core model in the modeling generally conceals the local SCO2 buildup and accordingly clouds judgment about variation trend of the local SCO2. 2) The settings of the local petrophysical properties for the low-porosity heterogeneous structures in the cores have a significant impact on the predicted SCO2 distribution in front of these structures. Particularly, the errors in their capillary entry pressure could lead to the significant underestimation of the local SCO2 near them. Consequently, the model outputs cannot reflect the local SCO2 buildup behavior. 3) Both magnitude and variation trend of the predicted local SCO2 could be numerically sensitive to 3D heterogeneity distribution, notably increasing the probability of the mismatching between model predictions and experimental observations. Comparatively, more efforts should be paid to the parameter setting of the heterogeneous structures in order to improve the reliability of the CO2 core flooding modeling.