塔河缝洞型油藏水驱后期开发方式研究

Development Mode of Tahe Fracture- Cave Reservoirs in Late Water Flooding Stage

塔河碳酸盐岩油藏储集空间以孤立溶洞和溶蚀裂缝为主,三维空间展布极其复杂,针对缝洞型油藏单元注气驱油规律认识不清、常规物模研究方法适用性较差的问题,设计制作了缝洞型可视化模型,开展不同驱替方式驱油规律研究。实验结果表明:"阁楼油"是缝洞型油藏水驱开发后期剩余油的重要存在形式;N2在高部位流动,作用于构造顶部"阁楼油",水在低部位流动,驱替低部位剩余油,泡沫在高、低部位均可流动,波及面积最大;对比不同注入方式提高采收率程度,泡沫驱最高达38.0%,其次为气水混注,提高采收率19.7%。实验研究揭示了缝洞型油藏注N2驱油规律,为后续段塞组合优化、注采参数设计和现场试验提供了技术支持。

The reservoir spaces of Tahe carbonate reservoirs are dominated by isolated caves and corrosion fractures,and the three-dimensional spatial distribution is extremely complex. Due to the unclear displacing law of unit gas injection in fracture- cave reservoirs and inapplicability of conventional physical simulation models,the fracture- cave visualization model was established to study the displacements under different displacing modes. Experimental result shows that the remaining oil mainly distributes in the form of attic oil. The injecting N2 flows and displaces remaining oil in the high parts. Water flows and displaces remaining oil in the low parts. Foam can both flow in the high and low parts and result in the largest swept area. Comparison of recovery factors under different injecting modes indicates that the recovery factor of foam flooding is up to 38. 0%,followed by gas- water mixed injection with a recovery factor of 19. 7%. The displacing law of N2 injection in fracture- cave reservoirs was researched by laboratory experiments,which can provide technical support to the subsequent slug combination optimization,design of injection- production parameters and field test.