高凝油油藏CO2驱转水气交替驱动态及储层伤害特征

Production performance and reservoir damage characteristics of CO2 water?鄄alternating?鄄gas injection after continuous CO2 injection for high pour?鄄point reservoir

许正恩 辛文明 刘誉 荣晓丹 管璐 王小宇

中国石油青海油田分公司采油三厂，青海 海西 816400）

No.3 Oil Production Plant, Qinghai Oilfield Company, PetroChina, Haixi 816400, China)

CO2驱及其水气交替驱（WAG）开发高凝油油藏导致蜡的沉积，是制约该类型油藏开发效果的关键因素之一。文中基于组合长岩心模型，开展了高凝油油藏连续CO2驱转WAG混相驱及非混相驱的室内实验，研究了该开发方式提高采收率的潜力，分析了对储层沿程伤害特征的差异性，并揭示了其机理。研究表明：高凝油油藏采用CO2驱转WAG混相驱可将采收率进一步提高19.30百分点，提升的采收率主要由前3个段塞贡献，且2#，3#段塞作用更显著，气油比及水油比的变化与注入相的对应上，大约滞后1个段塞周期；CO2驱转WAG非混相驱对储层的伤害主要发生在储层中间段，最高渗透率伤害率为4.58%，而混相驱对储层的伤害则发生在储层中后段，最高渗透率伤害率为6.72%。

The development of high pour?鄄point reservoirs by CO2 injection and water?鄄alternating?鄄gas(WAG) injection leads to wax deposition, which is a key factor restricting the oil recovery performance of this type of reservoirs. Based on a composite long core model, laboratory experiments of miscible and immiscible flooding after continuous CO2 injection for high pour?鄄point oil were carried out in this paper. Through miscible flooding experiment, the potential of enhanced oil recovery of high pour?鄄point oil was clarified and its production performance was summarized. The characteristics of permeability reduction for miscible and immiscible flooding were compared and analyzed, and the mechanism was revealed. The study shows that the oil recovery factor of CO2 injection can be further increased by 19.30% in the ensuing miscible CO2?鄄WAG process in high pour?鄄point reservoirs, and the recovery is mainly contributed by the first three slugs, especially the second and the third. The change of gas?鄄oil ratio and water?鄄oil ratio delays almost a cycle corresponding to the injection phase. The reservoir damage of ensuing immiscible CO2?鄄WAG process mainly occurs in the middle section, with a highest permeability reduction ratio of 4.58%, while the reservoir damage of ensuing miscible CO2?鄄WAG process mostly occurs in the middle and rear section, with a highest permeability reduction ratio of 6.72%.

10.6056/dkyqt201905015