次生大孔道地层精细调堵可视化模拟研究

长时间高强度注水开发导致疏松砂岩油藏形成次生大孔道，注入水无效循环，严重影响原油采收率。为此，研究了不同条件下堵剂的封堵规律，开展了精细调堵可视化模拟实验研究。研究结果表明:理论上，等剂量堵剂封堵深度越大波及系数越高，应致力于研发低成本深部调驱体系；剩余油分布对调堵作业效果具有重要影响，若剩余油集中在油井附近，则应进行深部堵水；而剩余油富集在水井附近，则应适当进行近井调剖；堵剂投放量存在一个经济限度，实验条件下封堵段塞长度为井距的10%左右时，封堵时效果最佳，且二次调堵效果优于一次调堵；对于弯曲大孔道地层，应尽可能在弯曲后段的远井地带进行封堵，以充分发挥大孔道高导流能力和井口附近高压力降的协同作用机理。

Visualized simulation of ifne proifle control and water plugging in reservoirs with secondary porous channels

Secondary porous channels are formed due to the long time forced water-flooding in unconsolidated sandstone reservoirs, which lead to the invalid circle of injected water and low oil recovery. Research on regular patterns of profile control and water plugging has great significance for field production. With the visualized simulation experiments, process of the improvement of sweep efficiency could be much more intuitive and concrete. The results showed that: sweep efficiency would be higher with the deeper location in theory, which needed the support of plugging agents with high flow capacity and low price; Results of the plugging operations depend on the distribution of remaining oil, plugging agents should be put deeper, if remaining oil was near production well; while this distance should not be so long with remaining oil near injection well; An economic limit was existed for the injection volume of plugging agents, which is about 10 percent under the condition of experiments, and injection twice showed a much better results. For reservoirs with bending channels, areas after the corner and far away from the wells were proved to be a good place to locate the plugging agents, which could make a full use of the high conductivity of porous channels and high pressure drop near wells.