注CO2对延长化子坪原油物性的影响

Effect of CO2 Injection on Physical Properties of Huaziping Crude Oil in Yanchang Oilfiled

张忠林 王 伟 赵习森 王世玉 黄春霞 姚振杰

ZHANG Zhonglin WANG Wei ZHAO Xisen WANG Shiyu HUANG Chunxia YAO Zhenjie

针对延长化子坪油区开展CO2驱存在驱油机理不明确的问题，采用PVT和细管实验，结合相态模拟，研究了注CO2对化子坪长6储层原油性质及其相态的影响。PVT实验表明，化子坪原油属于典型的欠饱和原油，气油比仅为68m3/m3左右，地层能量相对较弱；但在地层原始温压条件下 CO2在化子坪原油中的溶解量可达 34.17mol%，可使饱和油体积膨胀超过15％，黏度下降近50%，且CO2降压析出后对原油具有较强的提抽作用和溶解气驱能力。相态模拟和细管实验结果表明，化子坪原油与 CO2的一次接触和多次接触最小混相压力分别为33.31 MPa 和 14.27 MPa。因此，化子坪油藏 CO2驱为非混相驱，其驱油机理以膨胀、降黏、提抽及溶解气驱为主。图5表3参14

In order to clear mechanism of CO2 flooding in Huaziping oildom of Yanchang oilfiled，the effects of CO2 on physical properties and phase states of crude oil for Huaziping chang 6 reservoir were studied by PVT and slim-tube test combined with phase simulation. PVT experiment showed that the crude oil was a typical undersaturated crude oil with a gas-oil ratio of only about 68m3/m3，indicating that the Huaziping chang 6 reservoir is short of stratum energy. However，under the condition of original formation temperature and pressure，the dissolved amount of CO2 in crude oil could reach 34.17 mol%，which could make the volume of saturated oil expand by more than 15% and the viscosity drop by nearly 50%. Moreover，CO2 had a strong extraction effect on crude oil and dissolving gas drive ability during the process of decompressive operation. The results of phase simulation and slim-tube test showed that the minimum miscible pressure of primary contact and multiple contact were 33.31 MPa and 14.27MPa，respectively. Therefore，CO2 flooding in Huaziping oildom of Yanchang oilfiled belonged to immiscible flooding，and its displacement mechanism was dominated by expansion，viscosity reduction，extraction and dissolution gas flooding.

10.19346/j.cnki.1000-4092.2019.04.015