关键词: 岩盐, 白垩系, 大北克深, 库车坳陷, 储层

Abstract: The deep subsalt reservoir is an important field for natural gas exploration in Kuqa depression. The salt is widely developed in the Cretaceous reservoirs, and the detailed characterization and evaluation of salt-bearing characteristics of the reservoirs is of great significance to the optimization of exploration zones in this area. By taking 72 core samples in the Cretaceous sandstone reservoirs as the research object, based on thethin section identification, scanning electron microscope, spectrum and QEMSCAN analysis, the microscopic characteristics, distribution, diagenetic conditions, and provenance of salt in the Cretaceous reservoirs were studied. The results show that the halite crystals in the Cretaceous sandstone reservoirs occurred between clastic particles, on the surface of clastic particles, and in the dissolution pores and cracks, and they existmainly in three forms: Skeleton crystal, grain-shaped, and block-shaped. Different types of halite crystals have different atomic percentages of elements such as Na and Cl. In the whole Dabei and Keshen area, the distribution of halite content is higher in the west and lower in the east, and the closer the vertical distance is to the overlying gypsum layer, the higher the salt content. The aggregate form of the halite crystals is affected by many factors, such as salt source supply conditions, reservoir burial depth, sandstone particle size and sorting, etc. The salt source is mainly the dissolution seepage of the Paleogene paste salt sediments, and it may also be related to the lateral infiltration of saline fluids along tectonic faults. 

Key words: halite, Cretaceous, DabeiandKeshenarea, Kuqadepression, reservoir