阿尔及利亚某油田富气混相驱试验研究

THE PILOT TEST OF ENRICHED-GAS MISCIBLE FLOODING IN CERTAIN OIL FIELD OF ALGERIA

针对油田储层物性和流体特性,选择了具代表性的试验井组系统地开展了注富气混相驱提高采收率技术研究。室内研究结果表明,油藏适合开展混相驱提高采收率技术,长细管实验确定的液化石油气和天然气最小混相组成(MMC)在实验条件下能与地层原油混相;长岩芯流动实验结果表明在水驱含水98%后,实施混相驱可提高采收率15%以上。通过长细管模拟,确定油藏条件下(温度83.9℃,压力10.2 MPa),液化石油气与天然气最小混相组成为37.1∶62.9。利用数值模拟对注入方式、注入量、注入速度及注入层位进行了敏感性分析,推荐方案为EOR-1井组为交替注入,注入量0.10 PV,注入速度600 m3/d(地下体积),注Ⅱ、Ⅲ层,采Ⅰ、Ⅱ、Ⅲ层;EOR-2井组为连续注入,各井组注入量为0.30 PV,注入速度600 m3/d(地下体积)。推荐方案预测可提高采收率14%～15%。从矿场实施先期效果来看,EOR-1井组有明显的超覆现象发生,混相效果变差,建议采取适当措施抑制气窜;EOR-2井组混相效果理想。

By considering the reservoir quality and property of crude oil in certain oilfield of Algeria,we choose the representative well group to develop the Enriched-Gas miscible flooding systematically.Based on the laboratory experiment results,this reservoir is suitable to implement the miscible flooding.The slim tube experiment indicates that under the reservoir condition(83.9℃ and 10.2MPa),the MMC of LPG and nature gas is 37.1∶62.9.The results show that the MMC is capable of forming miscible fluid with the formation oil;the long core displacement experiment shows that after the water cut reaches 98%,the miscible flooding is able to enhance the oil recovery more than 15%.By numerical simulation,we analyze the sensitivity of a series of injection parameters including the injection rate,volume,mode and layers.The recommendation scheme is alternative injection in EOR-1 well group and continuous injection in EOR-2 well group,the injection ratio is 600m3/d(under the reservoir condition) and the injection volume is 0.3 PV.The simulation result of recommendation scheme can enhance oil recovery about 14%~15%.The result of pilot test reveals taht there is override phenomenon in EOR-1,the efficiency of miscible flooding is poor,and a kind of treatment is proposed to kill gas breakthrough;while the efficiency of miscible flooding in EOR-2 is very good and inspiring.