Core Flooding Application in EOR WAG Implementation: The Impact of Asphaltene Precipitation and Deposition

Abstract

Pressure depletion, temperature changes, and injection of CO2 or solvents into reservoirs can induce asphaltene precipitation and deposition in porous media. The dynamic displacement efficiency of a water alternating gas (WAG) process is controlled by relative permeability. Asphaltene deposition may alter the original characteristics of relative permeability curves. In this study, the effects of asphaltene deposition on the three-phase relative permeability using dynamic displacement experiments are investigated. A synthetic experimental approach is used to simulate the effect of in situ asphaltene deposition on the three-phase relative permeability of a water-wet system. Independent core flooding experiments are conducted on the different core-plug samples. The experimental results show that the asphaltene deposition changes the system from water-wet to mixed-wet. However, the results for the gas-oil system indicate it does not have a significant effect on gas-oil relative permeability. The oil relative permeability in a three-phase system shows different trajectories for oil iso-perm with different levels of asphaltene deposition until a certain gas saturation is achieved. Beyond this saturation point, all oil iso-perm trajectories merge, indicating no significant effect of asphaltene deposition. Understanding the impact of asphaltene precipitation and deposition in WAG application can provide valuable insights for optimizing enhanced oil recovery strategies.