提高高温高矿化度低渗油藏水驱开发效果研究

Improving the Development Effectiveness of Water Flooding in Medium-Low Oil Reservoir with High Temperature and Salinity

针对印度尼西亚Sungai Lilin油田油藏岩石渗透率低、温度高和注入水矿化度高等特点,以渗流力学为理论基础,通过仪器检测和物理模拟,研究了聚合物溶液和聚合物/表面活性剂二元复合体系在低渗油藏环境下的渗流特性及其影响因素,考察了岩心渗透率、注入时机、驱油体系和驱油剂组合方式对驱油效果的影响。二元复合体系中,部分水解聚丙烯酰胺相对分子质量400×104,浓度300 mg/L,SUN非离子型表面活性剂质量分数0.2%。结果表明,在溶剂水矿化度较高和岩心渗透率较低时,二元复合驱油体系的阻力系数和残余阻力系数大于聚合物溶液。采用二元复合体系可以大幅提高原油采收率,并且岩心渗透率越大、注入时机越早,采收率越高。注入0.57 PV二元复合体系时的采收率增幅为17.8%。推荐二元复合体系段塞尺寸为0.38 0.57 PV,考虑到油藏非均质性比较严重,建议在二元复合体系主段塞之前添加Cr3+聚合物凝胶(聚合物浓度300 mg/L,聚铬质量比270∶1)前置段塞,段塞尺寸0.05 0.08 PV。

Based on Indonesia Sungai Lilin oil reservoir with low permeability, high temperature and high salinity of injected water, the seepage characteristics and its influencing factor of polymer solution and surfactant-polymer system in low permeability reservoir and the effect of permeability, injection timing and combination modes of displacement system and displacement agent on displacement efficiency were studied by instrument testing and physical simulation. In polymer-suffactant system, the molecular weight of HPAM was of 400 × 10^4 and the concentration was of 300 mg/L, while the content of non-ionic surfactant （SUN） was of 0.2%. The results showed that under the condition of high salinity of solvent water and low permeability of core, the resistance factors and residual resistance factors of polymer-surfactant system were greater than that of polymer solution. Polymer-surfactant system could significantly improve the oil recovery. The higher permeability was and the earlier system was injected, the higher oil recovery was. A recovery increment of 17.8% could be achieved when the polymer-surfactant system was injected with a slug of 0.57PV. The recommended slug size was of 0. 38-0.57PV. Considering the high salinity of oil reservoir and heterogeneity, the polymer gel contained Cr^3＋ （cp = 300 mg/L, polymer： Cr^3＋=270：1 ） with slug size 0. 05-0.08 PV should be injected to adjust profile before polymer-surfactant system injected.