Effect of Phase Behavior and Mass Transfer Mechanisms on Crude Oil Recovery and CO2 Storage in a CO2 Injection Process in Colombian Reservoirs

Abstract In this study, the potential of the CO2 injection process in CO2 solubility trapping and enhanced oil recovery was analyzed for immiscible and near miscible conditions in Colombian reservoirs. A compositional conceptual simulation of the CO2 injection process was carried out for black oil and heavy crude oil. Since in the early stages of evaluating the EOR-CCUS process there is no experimental data on the interaction of live crude oil-CO2 and CO2-formation water, a methodology based on the characterization of the C7+ fraction through physical distillation curves (ASSAY III), compositional analysis and correlations (Sanchez Lemus 2015) was developed to generate a gas-liquid behavior predictive model with the experimental PVT data. Then, for the estimation of the minimum miscibility pressure, correlations, multiple contact calculations, and 1D simulation of the Slim-Tube test were used (Hoier 1997). These predictions were made with different binary interaction coefficients (Xu et al., 2019) between the pseudocomponents of crude oil and CO2 to establish miscible phase behavior scenarios or partial solubility, and thus evaluate different cases of recovery efficiency and CO2 solubility through the numerical compositional simulation, where CO2 can vaporize light oil components and/or condensate into the oil. To estimate the CO2 sequestration potential in the formation water, a formation water-CO2 thermodynamic model was built from the modified Peng-Robinson equation of state (EOS) and correlations (Harvey 1996; Nghiem et al. 2004; Søreide and Whitson 1992). The results show a dependency of the CO2 recovery factor and storage on the type of process: immiscible, near miscible or miscible, and the type of hydrocarbon. The difference in the salinity of water, pressure and temperature conditions in the analyzed fields also had a considerable influence in the retention of CO2 in the formation water. These results are consistent with experimental observations reported in the literature (Abedini and Torabi 2014; Esene et al. 2019) This study contributes a promising methodology to carry out feasibility studies of CO2 enhanced recovery processes and estimations of CO2 storage potential by solubility trapping when crude oil- CO2 and CO2-formation water experimental data are not available, but robust information is on hand for the characterization of the reservoir fluids. The management of uncertainty provides ranges of variables such as minimum miscibility pressure, condensation and vaporization mechanisms and solubility of CO2 in water. In this way, it is feasible to generate several scenarios to evaluate future CCUS projects in Colombian reservoirs and can be applied to fluids worldwide.