中高渗砂砾岩油藏聚合物驱后非均相复合驱技术研究OA

After polymer flooding in Interval Ⅳ 1-3 of the northern block of Shuanghe Oilfield,severe underground water-channeling zones have developed,and the remaining oil distribution has become increasingly scattered and complex.To further enhance oil recovery(EOR),this study focused on the optimization of heterogeneous composite flooding systems and the investigation of their displacement mechanisms.Based on the reservoir pore-throat structure characteristics and remaining oil distribution rules,a heterogeneous composite flooding system with graded plugging capacity was developed.Physical simulation experiments show that after polymer flooding,0.50 pore volume(PV)of high-concentration polymer flooding,binary composite flooding,and heterogeneous composite flooding systems were injected separately.The oil recovery rate of 2 000 mg/L polymer flooding was only increased by 5.2%,whereas that of the heterogeneous composite flooding system was at least 2.5%higher than that of binary composite flooding.This indicates that the PPG particles in the heterogeneous composite flooding system exert viscoelastic effects,which promote fluid diversion and improve oil displacement efficiency.Field pilot test data demonstrate that the injection pressure in the test area increased by 5.4 MPa,the daily oil production rose from 24.0 t(before injection)to 65.7 t,the cumulative oil increment reached 8.2×104 t,and the stage oil recovery rate was enhanced by 2.1%.The study confirms that heterogeneous composite flooding technology can effectively produce the remaining oil in reservoirs after polymer flooding,thereby providing a new technical scheme and theoretical support for EOR in similar high-water-cut reservoirs.