断块油藏人工气顶-底水双驱替渗流特征

Flow characteristics of artificial gas cap-bottom water drive in fault block reservoir

在注水开发后期,断块油藏会进入高含水阶段,剩余油主要集中在构造高部位,水驱效果不理想,基于该问题开展断块油藏双驱替渗流特征研究。通过双驱替可视化实验,观察油、气、水的运移规律;在模拟油藏条件下进行岩心管驱替实验,总结双驱替增产机制并进行治窜措施分析。结果表明油藏顶部注气会在重力分异作用下形成人工气顶,驱动高部位剩余油,改善水驱后期开发效果;在可视化实验及岩心管实验中,双驱替阶段采收率提高幅度分别为6.43%和5.80%;在双驱替渗流过程中,油水、油气界面的推进导致剩余油分布状态发生改变,驱替介质的流动特性取决于生产压差的建立以及储层渗透率的变化;由于气体的黏性指进和储层非均质性的影响,驱替过程中易产生气窜现象,建立的针对倾斜断块油藏不同开发阶段注气增产的方法可有效改善气顶驱的增产效果。

The fault block reservoir enters the high water cut in the last stage of bottom water flooding.The remaining oil is mainly concentrated in the high part of the structure,and the effect of water flooding is not ideal.The flow characteristics of the two-way drive in fault block reservoir were studied to solve this issue.The migration characteristics of oil,gas and water were observed through the two-way drive visualization experiment.Then,the core tube flooding experiment was carried out in simulated reservoir conditions,and the stimulation mechanism of two-way drive was summarized and the channeling control measures were analyzed.The results of experiment show that the gas injection at the top of the reservoir can form an artificial gas top under gravity differentiation and drive the remaining oil to improve the later development effect of water flooding.In the visualization experiment and the core tube experiment,the increase in recovery factor of the two-way drive stage is 6.43%and 5.80%,respectively.In the process of two-way drive,the advancing of the oil-water and oil-gas interface results in the change of remaining oil distribution.The flow characteristics of the displacement medium depend on the establishment of production pressure difference and the change of reservoir permeability.However,due to the viscous fingering of gas and the heterogeneity of reservoir,gas channeling is prone to occur during the displacement process.A set of methods for increasing gas production in different development stages of inclined fault block reservoirs has been established to improve the stimulation effect of gas-cap drive.