CCUS in a Complex Fluid Column, From Gas Condensate to Heavy Oil: A Mature Compositional Reservoir Real Case in the North of Monagas, Venezuela

Carbon Capture Utilization and Storage (CCUS) in El Carito-Mulata-Santa Barbara Field represents a great challenge due to the multiple phases present in the reservoir (significant variation of composition with depth from gas condensate to heavy oils and Tarmat) and the presence of local water zones and aquifers. For more than 20 years this field has been under pressure maintenance to avoid asphaltene precipitation issues, by injecting water along with natural gas, and several studies have been focused on the injection of alternative gases such as carbon dioxide and nitrogen. The scope of this study is to evaluate the feasibility of CO2 injection in El Carito-Mulata-Santa Barbara Field through a compositional simulation model, and to understand the main mechanisms of the process. To evaluate the feasibility of CO2 injection in the study area, a compositional model previously tuned with real laboratory and field data was used, including PVT tests, swelling, slim tube and coreflood tests. This compositional model considers the three parameters of the Peng Robinson equation of state for the adjustment of laboratory experiments and a lumping scheme that allows for the evaluation of natural gas, nitrogen, and carbon dioxide injections. Different scenarios were evaluated in the full field numerical simulation model to predict the injection of CO2 in different zones of the reservoir (in the gas condensate zone, black oil zone and in the water zone), as well as the possible WAG CO2 injection. Results of this study predict the impact of mechanisms such as miscibility/solubility/oil swelling on the evaluation of CCUS in El Carito-Mulata-Santa Barbara Field, and their effect on the recovery of hydrocarbons. The importance of data acquisition and lab test programs as well as a field monitoring plan for the calibration of the reservoir model to current reservoir conditions are highlighted. These results will provide input for the technical-economic evaluation of CCUS in El Carito-Mulata-Santa Barbara Field and future feasibility studies of CCUS for field application in Venezuela.