Various problems exist in the development of Fuyang extra-low permeability oil layer using water flooding, including injection difficulty, recovery difficulty, low effectiveness, and low recovery rate. To solve these problems, a CO₂ flooding test was carried out at Shu101 well block in Daqing Yushulin Oilfield. Systematic evaluation of the displacement state, development characteristics and effects of CO₂ flooding was conducted. The results show that when the injection rate of CO₂ was 0.1 HCPV, through comparison of high pressure physical properties of two samplings, the light component increased by 5.7%, and the minimum miscibility pressure decreased from 32.2 MPa to 28.6 MPa, a drop of 3.6 MPa. Three kinds of displacement states existed in the test area: miscible, semi-miscible and immiscible phases, which account for 2/8, 1/8, and 5/8, respectively. Through research and oilfield practice, the development and adjustment technology of CO₂ flooding for different gas injection stages and different types of wells was developed. The oil recovery rate in the test area remained above 1% for four consecutive years. Numerical simulation predicted that the ultimate recovery using CO₂ flooding will be 10% higher than that using water flooding.

CO₂ flooding  /  ultra-low permeability oilfield  /  Fuyang reservoir