Experimental investigating of the effect of CO2 injection parameters on asphaltene precipitation and formation damage in live oil

With the increasing consumption of oil in the world and increasing production of oil from oil reservoirs, the reservoir pressure starts to decrease. On the other side, the use of oil leads to an increase in carbon dioxide production in the environment and causes global warming.

One of the effective methods of reducing the amount of carbon dioxide emitted into the atmosphere and increasing the reservoir's pressure is CO₂-EOR and carbon capturing and storing (CCS) which injects produced carbon dioxide from industrial sources into underground reservoirs. Carbon dioxide reduces oil viscosity and increases oil mobility producing an economical state. Moreover, with CO₂-EOR and CCS carbon dioxide can be stored in a depleted reservoir and helps reduce pollution and global warming.

Besides the environmental and economic benefits due to reducing carbon dioxide emissions to the atmosphere and increasing oil production, CO₂ injection causes various problems in the formation. Many experiments indicate that asphaltene precipitation and wettability alteration caused by asphaltene, dissolution/precipitation of rock, salt precipitation, and sludge formation are some of the problems that occur during CO₂ injection operations in low pressure and temperature. However, few experiments evaluate asphaltene precipitation effective factors, such as pressure, injection rates, temperature, etc., in high temperatures and pressure (HPHT) near reservoir conditions. Therefore, there was a need for a comprehensive investigation of various factors and the impact of each of them on the asphaltene precipitation and formation damage in HPHT conditions, so this research was designed to help future simulation and industrial utilization.

A core-flood setup was prepared to conduct CO₂ flooding experiments and formation damage studies in HPHT conditions. The main objective of this study was to evaluate the effect of different parameters including pressure, injection rate, and type of injected gas on asphaltene and its effect on formation damage caused by CO₂ injection. The second goal of this study was to investigate the optimum injection in every section. The third goal was to determine the oil recovery during the process of CO₂ injection in different conditions.

The results showed that an injection rate of 0.1 cc/min and higher injection pressures minimized asphaltene precipitation and maximized oil recovery. Replacing CO₂ with natural gas liquids (NGL) gas reduced oil production and asphaltene precipitation. Overall, the experiments demonstrated the importance of optimizing injection parameters to limit formation damage during CO₂ flooding. © 2024 The Authors. Greenhouse Gases: Science and Technology published by Society of Chemical Industry and John Wiley & Sons Ltd.