库车油气系统北带中、新生界主要储层孔隙流体超压成因探讨

库车油气系统北带在第三系盐－膏质区域盖层之下已经发现了6个孔隙流体超压的大小、中型气田,其主要产层的压力系数多在1．8－2．0之间。通过对他们的地质特征,分布特点和地应力环境分析,及与系统南带各油气田和北带第三系盐－膏质区域盖层之上油田对比研究认为：在第三系盐－膏质区域盖层之下封闭体系中高速充填－强烈压实和剧烈构造挤压是克拉2等气田孔隙流体超压的根本原因;由二诱发的深部岩系中（包括气源岩在内）更高的超压流体不断注入是主要储层超压生成的物理机制;生烃过程中产生的相变膨胀压力、构造挤压引发的抬升也会对气层超压的形成有一定的影响。

DISCUSSION ON ORIGIN OF OVERPRESSURE IN MAIN RESERVOIR OF THE MESOZOIC AND CENOZOIC IN NORTH ZONE OF KUQA PETROLEUM SYSTEM

Six giant and middle gas fields with overpressure, whose pressure coefficients measure mostly from 1.8 to 2.0 in main reservoir, were discovered under the Tertiary halite-gypsum regional cap rocks in the north zone of Kuqa petroleum system. According to analysis on geological characteristics and geostressed environments of these gas pools, and comparative study between the north zone and south zone, and the pools under halite-gypsum regional cap rocks and the pools above the regional cap rocks, the ultimate origin of overpressure was rapid filling and intense compaction, and strong tectonic compression inside closed system. Continuous injections of overpressure fluid caused by the rapid filling and strong tectonic compression from deeper stratum (including gas source rock) are the formation mechanism of the overpressure in the main reservoir. Expansion forces by hydrocarbon generation and rising processes caused by rapid filling and strong tectonic compression might affect formation of the overpressure in a certain extent.