应力敏感裂缝型储层多相渗流规律实验

Experiment on multiphase flow rules in stress-sensitive fractured reservoirs

针对隐裂缝发育储层存在的压裂或者增注过程中,注入压力不升或者升幅不明显的问题,采用室内物理模拟实验进行多相渗流规律研究。自制应力敏感裂缝型储层大尺寸三维岩心和纯砂岩储层大尺寸三维岩心,进行不同岩心的应力敏感测试与分析;开展近活塞式驱替和非活塞式驱替实验进行多相渗流规律分析;利用油藏数值模拟反演方法,明确应力敏感裂缝型储层应力敏感产生机理和水淹、水窜形成机制。研究结果表明,应力敏感裂缝型储层的应力敏感性强,驱替过程中受裂缝或裂隙张开的影响,储层渗流能力增大;宏观和微观上存在2个水驱前缘,即裂缝中的水驱前缘和基质中的水驱前缘;沿面窜流是应力敏感裂缝型储层最主要的窜流方式之一,易导致水淹程度极不均匀。实验研究揭示了应力敏感裂缝型储层多相流体的渗流规律和水窜机制,为应力敏感裂缝型储层高效开发和优化设计提供了科学指导和理论依据。

In view of the problem that the injection pressure does not increase or the increase is not obvious during the fracturing or injection process of the reservoirs with hidden fractures,the study on multiphase flow rules was performed by using physical simulation experiments.The large-scale 3D cores from stress-sensitive fractured reservoirs and the large-scale 3D cores from pure sandstone reservoirs were made to test and analyze stress sensitivity of different cores.The near-piston-like displacement and nonpiston-like displacement experiments were carried out to analyze multiphase flow rules.By using the reservoir numerical simulation inversion method,the stress-sensitivity mechanism of stress-sensitive fractured reservoirs and the formation mechanism of water flooding and water channeling were clarified.The research results show that the stress-sensitive fractured reservoirs have strong stress sensitivity,and the flow capacity of the reservoir increases due to the influence of fractures or fracture opening during the displacement process;there are two water flooding fronts in the macroscopic and microscopic perspectives,that is,the water flooding front in the fractures and the water flooding front in the matrix;channeling along surface is one of the most important channeling patterns in stress-sensitive fractured reservoirs,which can easily lead to extremely uneven water flooding.The study reveals the flow rules and water channeling mechanism of multiphase fluids in stress-sensitive fractured reservoirs,which can provide a scientific guidance and theoretical basis for efficient development and optimal design of stress-sensitive fractured reservoirs.