Gas injection serves as a main enhanced oil recovery (EOR) method in fractured-vuggy carbonate reservoir, but its effect differs among single wells and multi-well groups because of the diverse fractured-vuggy configuration. Many researchers conducted experiments for the observation of fluid flow and the evaluation of production performance, while most of their physical models were fabricated based on the probability distribution of fractures and caves in the reservoir. In this study, a two-dimensional physical model of the karst fault system was designed and fabricated based on the geological model of TK748 well group in the seventh block of the Tahe Oilfield. The fluid flow and production performance of primary gas flooding were discussed. Gas-assisted gravity flooding was firstly introduced to take full use of gas–oil gravity difference, and its feasibility in the karst fault system was examined. Experimental results showed that primary gas flooding created more flow paths and achieved a remarkable increment of oil recovery compared to water flooding. Gas injection at a lower location was recommended to delay gas breakthrough. Gas-assisted gravity flooding achieved more stable gas-displacing-oil because oil production was at a lower location, and thus, the oil recovery was further enhanced.

中文翻译：

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塔河裂缝性碳酸盐岩缝状碳酸盐岩储层二维地质物理模型中的注气法提高采收率

注气是缝洞型碳酸盐岩油藏的主要提高采收率的方法，但由于缝洞型构造的多样性，注气效果在单井和多井组之间是不同的。许多研究人员进行了观察流体流动和评价生产性能的实验，而他们的大多数物理模型是根据储层中裂缝和溶洞的概率分布构造的。本研究基于塔河油田七区TK748井群的地质模型，设计并制作了岩溶断层系统的二维物理模型。讨论了一次天然气驱的流体流动和生产性能。首次引入气体辅助重力驱以充分利用气油重力差，并研究了其在岩溶断裂系统中的可行性。实验结果表明，与水驱相比，一次天然气驱产生了更多的流动路径，并显着提高了石油采收率。建议在较低位置注入气体以延迟气体突破。气体辅助重力驱由于产油量较低，因此驱油效果更加稳定，从而进一步提高了采收率。