STUDY OF CO₂ MISCIBLE FLOODING TECHNIQUE IN THE CAOSHE OIL FIELD, THE QINTONG SAG, THE NORTHERN JIANGSU BASIN

The Taizhou Formation reservoir in the Caoshe Oil Field of the Qintong Sag of the Northern Jiangsu Basin is a complex fault block reservoir.Border faults work as good barrier while internal ones are unbounded,resulting in communication of reservoirs.Injection of CO₂ in laboratory experiment obviously expands crude oil and reduces viscosity,hence is qualified for CO₂ miscible flooding.Before gas injection,there are many problems with flooding pattern of the Taizhou Formation reservoir.For example,the division of development series is too simple;interlayer contradicts with each other;well pattern in some region is not perfect;plane productions are unbalanced;and vertical production degrees are different,et al.Dynamic monitoring after CO₂ injection has proved that,gas entry profiles of gas injection well are improved;formation reaches the minimum miscibility pressure;heavy components in crude oils are produced;and production in the whole region is stable and advancing.