二氧化碳混相压裂吞吐实验

针对南堡凹陷高5断块V油组常规水力压裂开发效果不佳的问题,通过开展PVT和岩心混相吞吐实验,明确CO₂混相压裂吞吐提高采收率作用机理,并利用矿场试验进一步验证技术有效性。研究结果表明:在目前地层压力(33.00 MPa)下,CO₂与原油可实现混相,且注入摩尔分数为60%的CO₂后原油体积膨胀41.01%,黏度降低33.08%,密度增加7.28%,表明CO₂对原油具有较好的增溶、膨胀、降黏作用;CO₂混相压裂吞吐采出程度可达到60%以上。试验井CO₂混相压裂吞吐后稳定生产26个月,累计增油2 200 t,原油重质组分得到了有效动用。该研究为低渗及致密油藏效益开发提供了有效技术途径。

Test of CO2 Miscible Fracturing and Huff and Puff

To address the problem of poor development of conventional hydraulic fracturing in V Formation of Fault Block Gao 5, Nanpu Sag, PVT and core miscible huff and puff tests were conducted to clarify the mechanism of enhancing oil recovery by CO₂ miscible fracturing and huff and puff, and the technical effectiveness was further verified by field tests. The study results showed that: at the current formation pressure (33.00 MPa), CO₂ and crude oil could be mixed, and the crude oil volume was expanded by 41.01%, the viscosity decreased by 33.08%, and the density increased by 7.28% after the injection of CO₂ with a mole fraction of 60%, and CO₂ was effective in solubilization, expansion and viscosity reduction of crude oil; the recovery efficiency could reach more than 60% by miscible fracturing and huff and puff. After CO₂ miscible fracturing and huff and puff, the production of test wells was stable for 26 months, with a cumulative increase of 2 200 t in oil production, and the heavy components of crude oil were effectively utilized. The study provides an effective technical approach for the profitable development of low-permeability tight reservoirs.