塔里木盆地库车坳陷盐构造特征及其与油气的关系

库车坳陷发育古近系和新近系两套膏盐层,其分布特征各异.膏盐层的塑性流动形成多种类型的盐构造.盐构造演化可大致分为4个阶段.前两个发育阶段与盐序列本身及其上覆地层的差异负载作用有关,后两个发育阶段主要与南天山的山前冲断构造作用有关.盐构造在不同的演化阶段具有不同的形态特征,因而对库车坳陷的油气成藏至关重要.盐构造不仅有利于储层发育、油气保存和圈闭形成,而且有利于油气运聚,构成了油气成藏的界限.盐构造发育区是大-中型油气田勘探的有利地区.

SALT STRUCTURE CHARACTERISTICS AND ITS RELATION TO HYDROCARBON ACCUMULATION IN THE KUQA DEPRESSION, TARIM BASIN

There developed two sets of salt bed in the Kuqa depression, Tarim Basin, namely, the Paleogene Kumgramu Group and the Neogene Jidike Formation, with varied characteristics of the both salt beds. The salt structures were well developed there, especially, the plastic flow structures. Four stages could be distinguished in the evolutional process of the salt structures. In the first and second stages the development of salt structures was related mainly with the succession of salty strata and differential loading effects, while in the third and forth stages the evolution of salt structures was mainly controlled by the thrusting in the area south of the Nan-Tianshan Mountains. Varied morphological salt structures could be observed in different stages, which might play an important roles in reservoir-forming in the Kuqa Depression. The salt structures provided some conditions, not only for better developing of cap rocks, oil-gas reservation and formation of large-scale traps, but also for higher porosity, more favorable migration and accumulation, so as to be boundaries of oil gas pools. In short words, the areas where the salt structures well developed might be potential regions for exploration of large-mesoscopic oil-gad fields.