库车坳陷的断裂有效运移通道及其物理模拟

Effective migration pathway and its physical simulation in the Kuqa Depression

库车坳陷区的变形,垂向上可分为3大构造层:盐上层、新生代膏盐层和盐下层。根据该地典型构造的含气性差异,分析了断裂有效输导天然气的地质条件,认为充足且有效的气源条件、沟通源岩与圈闭且不断穿区域性盖层的盐下断裂以及完整的圈闭是决定天然气沿断裂运聚成藏的重要条件,因而不断穿区域性盖层的盐下断裂是有效油气运移通道,并用物理模拟对其进行了验证。通过分析与断裂有效运移通道相配置的砂体的封闭程度、体积和物理性质的差异发现:沿断裂有效运移通道运移的天然气向断裂两侧储层分流的优势运移路径明显不同,在发育断裂有效运移通道时,断裂带内部的流体总是向着断裂带两侧封闭程度差、体积大和物性好的储层分流运移。

There developed the salt-underlying beds, the Cenozoic salt（ or gypsum）beds and the salt- overlying beds in the Kuqa Depression, Tarim Basin. Based on the difference of contain gas for typical structures in the depression, this paper analyzed the geologic conditions of fault transporting natural gas effectively, and thought that the full and effective gas source, the faults of linking source rock and trap but not through regional cap rock and entire trap were significant conditions for natural gas migration and accumulation through fault. So, the salt-underlying faults which did not cut through the regional cap rock were effective hydrocarbon migration pathways, and this viewpoint was verified by our physical simulation. Based on analyses on the sealing degrees, volumes and physical properties of the sand bodies related to the effective migration pathway of fracture, it was found that the dominant migration pathways were obviously different for natural gas migrating along the pathways to flow into the reservoirs in both sides of the fault. In situation of the fracture effective migration pathway developing, the fluid bodies inside the fault zone were always flowing to the reservoirs which had relatively poor sealing, larger volume and better physical properties .