The characteristics of produced oils in the miscible CO₂ displacement process

Abstract

CO2 flooding is an effective technique for enhancing oil recovery by changing the hydrocarbon fluid’s characteristics. One of the fundamental mechanisms of the interaction between CO2 and hydrocarbon fluid by miscible CO2 injection is the extraction phenomenon of the hydrocarbon components by CO2. It results in altered produced and residual oil characteristics. This study aims to examine the characterizations of produced oil during the process of CO2 displacement. It is critical to anticipate any issues that can arise from miscible CO2 flooding, such as asphaltene deposition. A light-dead oil sample from an Indonesian oil field was used in this investigation. The miscible CO2 displacement process was conducted by a slim tube experiment at operating temperature of 90°C and 70°C, which represents the reservoir and surface temperature, respectively. The properties of produced oil were further characterized by analyzing the composition based on its polarity, including saturate, aromatic, resin, and asphaltene. The results show that increasing injection pressures decrease resin and asphaltene fractions in produced oil. Furthermore, the proportions of asphaltene and resin fractions in the crude sample exhibit a significant decrease when conducted at a lower temperature in comparison to when carried out at a higher temperature. This study helps to explain how the displacement process by CO2 affects the properties of the produced oil.