注CO_(2)改善河南双河油田低渗储层注水能力机理研究

Mechanism of CO_(2) injection to improve the water injection capacity of low permeability reservoir in Shuanghe Oilfield in Henan

针对双河油田低渗储层注水能力差、注水水质不达标和高凝原油蜡沉积等问题,通过自主设计的水-CO_(2)储层注入能力评价装置,开展流动性实验、CO_(2)驱油实验,结合岩心扫描电镜等测试手段,明确双河低渗储层注水能力差的主要机制,探索CO_(2)改善低渗储层注入能力的主要机理。结果表明,产出水中的悬浮颗粒和油中蜡晶等组分的沉积可导致孔隙堵塞,从而降低储层的注水能力。CO_(2)对产出水中无机悬浮颗粒及岩石碱性矿物、碳酸盐岩矿物有明显溶蚀作用,是显著提高储层注水能力的主要机理。CO_(2)可溶解在岩石表面的原油蜡质组分沉积,有效改善储层注水能力。同时,CO_(2)驱提高采收率效果明显,采收率提高13.01%~21.51%,后续水驱进一步提高5.40%~6.04%。研究表明:注CO_(2)可显著改善双河油田低渗储层注入能力,为CO_(2)增注驱油技术在现场应用提供理论支撑。

Addressing issues such as poor water injection capacity,substandard water quality and wax deposition of high pour point crude oil in low permeability reservoirs of Shuanghe Oilfield in Henan,an independently designed water-CO_(2) reservoir injection capability evaluation device was utilized to conduct flowability experiments and CO_(2) displacement tests.Combined with core scanning electron microscopy and other testing methods,the main mechanism of poor water injection capacity of Shuanghe low permeability reservoirs was clarified,and the main mechanism of CO_(2) improving the injection capacity of low permeability reservoirs was explored.The results show that the deposition of suspended particles in the produced water and wax crystals in the oil can lead to pore blockage,thereby reducing the water injection capacity of the reservoir.CO_(2) has a significant dissolving effect on inorganic suspended particles in produced water and on alkaline minerals and carbonate minerals in rocks,which is the main mechanism for significantly enhancing the reservoir's water injection capacity.CO_(2) can dissolve paraffin deposits on the rock surface,effectively improving the reservoir's water injection capability.At the same time,the effect of CO_(2) flooding is obvious,the recovery rate is increased by 13.01%~21.51%,and the subsequent water flooding is further increased by 5.40%~6.04%.This study shows that CO_(2) injection can significantly improve the injection capacity of low permeability reservoirs in Shuanghe Oilfield,and provides theoretical support for the field application of CO_(2) injection and oil displacement technology.