Long Core Simulation of Advanced CO2 Injection in Ultra-Low Permeability Reservoir

摘要

CO2 flooding is a promising enhanced oil recovery method both on technical and environmental bases, especially for ultra-low permeability reservoir, because this reservoir is characterized by low porosity, ultra-low permeability, low deliverability, water sensitive, and water-flooding inefficient. In this paper, crude oil and cores from H-59 block of Jilin oilfield were used to conduct tests for studying oil recovery of different types of gas injection. Continuous CO2 steam injection and advanced CO2 steam injection were compared to select the optimal injection patterns. Results indicate that oil recovery of advanced CO2 steam injection is higher than continuous CO2 steam injection. It is considered that injecting CO2 steam before production can keep the pressure of the ultra-low permeability reservoir effectively, and the advanced injected CO2 can highly contact with crude oil, which will decrease the viscosity and swell the volume of the oil, ultimately improve mobility of the oil.