高温高压碳酸盐岩油藏合理驱替方式及参数实验研究

Experimental investigation of reasonable displacement modes and parameters in a high-temperature and high-pressure carbonate reservoir

伴生气回注逐渐成为海上油田兼顾气处理和提高采收率的重要技术之一.为揭示海上深水目标油田特殊油藏条件下合理开发方式和参数,开展细管驱替、高温高压长岩心驱替等系列实验,重点研究不同驱替方式和驱替参数对开发效果的影响.实验结果表明:在地层原始条件下,目标油田伴生气(主要成分为二氧化碳和甲烷)回注可形成混相气驱.在目标油田储层物性条件下,水气交替驱最终驱油效率为83.0%,相比纯水驱和纯气驱驱油效率分别提高39.8%和9.8%.水气交替注入在大幅提高驱油效率同时,有效延缓见水时间(约为纯水驱的4倍)和见气时间(约为纯气驱的2倍).水、气注入顺序对最终驱油效率无明显影响,但实验条件下优先注气在驱替初期表现出更高的产油速度.实验参数范围内,目标油田最优注入段塞大小为0.1倍烃孔隙体积(HCPV),最优气水比为1∶2.本实验研究结果可为目标油田开发方案设计及现场应用提供有益指导.

Associated gas injection is becoming a broadly practiced technique in some offshore oilfields as an alternative to combine managing produced gas and increasing recoveries.In order to investigate the effects of different injection modes and injection parameters on production performance under specific reservoir conditions of the target oilfield,slim-tube test and extensive long-coreflood experiments were carefully conducted.The results showed that the main composition of the associated gas was CO2 and CH4.Under the target reservoir conditions,miscible flood could be achieved with the associated gas injection.For WAG food process,the ultimate oil displacement efficiency was 83.0%,which was 39.8%and 9.8%higher than that of water food and gas flood,respectively.WAG process above minimum miscibility pressure presented a great potential of enhancing oil recovery and delaying water production(near 4 times longer than water flood)and gas channeling(near 2 times longer than gas flood).Water and gas injection sequence has little impact on ultimate oil recovery,while faster oil production was observed when gas slug was firstly injected.Within the tested parameters,the optimal slug size and gas-water ratio was 0.1 HCPV and 1∶2,respectively.The experimental results obtained in this paper is essential to guide the development plan and the field application.