Volume 56

Application of CO2 Immiscible Flooding Technology of Low-permeability Oil Fields in Northern Songliao Basin Shukun Wang

Abstract

The oil reservoir in the peripheral oil fields of northern Songliao Basin is characterized by low permeability and complex structures. With the decreasing oil production, there is an urgent need to change the injection and production methods. Laboratory experiments is performed in order to study the application of CO2 displacement technology. The results of laboratory experimental studies shows that CO2 injection can significantly increase the fluidity of crude oil through dissolution, viscosity reduction, and gas-injection expansion. It indicates that CO2 has good dissolution, viscosity reduction, and gas injection expansion effects, which can significantly increase the fluidity of crude oil. Based on the characteristics of the reservoir, it is believed that the low-permeability reservoir around northern Songliao Basin is suitable for CO2 flooding. CO2/water alternating injection increases oil recovery by 28.13 percentage points compared to water flooding.Production parameters are optimized by numerical simulation, the results show that the higher the level of formation pressure recovery, the better CO2 flooding effect. The optimization result is to use a gas to water ratio of 3:1, with a water gas alternation cycle of 2 months of water injection and 2 months of gas injection.This method can increase oil recovery by 11 percentage points compared to water flooding,utilizing remaining oil effectively. The research has reference significance for CO2 immiscible flooding in other low-permeability reservoirs.

Keywords low permeability,CO2 flooding,enhanced oil recovery, parameter optimization