Abstract: Phase of CO₂ flooding is studied, combining with MMP and maximum gas injection pressure in the study area. The results show that the MMP is 22.2 MPa. The fracture pressure of formation is 33.88 MPa. The maximum gas injection pressure of wellhead is 15.8 MPa. The gas injection pressure is 10.5 MPa, and corresponding injection gas pressure of well bottom is 19.1 MPa. CO₂ flooding belongs to immiscible flooding. When the gas injection pressure of wellhead is increased to 15.0 MPa, the bottom hole pressure is 23.6 MPa, which is higher than the minimum miscible pressure, there is miscible zone near the well area in the gas injection well.

Key words: Yanchang oilfield, CO₂ flooding, Phase, Injection pressure, Immiscible

摘要： 为了研究延长油田J区块CO₂驱相态，根据细管实验得到工区最小混相压力，考虑地层破裂压力计算井口最大注气压力，结合工区目前井口注气压力分析了CO₂驱相态。结果表明，工区CO₂驱最小混相压力为22.2 MPa,井底破裂压力为33.88 MPa，井口最大注气压力可达15.8 MPa；目前工区单井最高注气压力为10.5 MPa，对应注气井底压力为19.1 MPa，低于最小混相压力，属于非混相驱油。当井口注气压力提高到15.0 MPa时，注气井底压力为23.6 MPa，高于最小混相压力，注气井近井地带存在混相区。

关键词: 延长油田, CO₂驱, 相态, 注气压力, 非混相