四川盆地川西坳陷高异常地层压力分布特征

DISTRIBUTING CHARACTERISTICS OF ABNORMAL PRESSURE IN THE WEST SICHUAN DEPRESSION OF SICHUAN BASIN

本文通过分析川西地陷20多个含气构造的主要地层压力资料,对川西坳陷高异常地层压力的分布特征有了一定的认识.认为川西高异常地层压力在纵向层位上主要分布于侏罗系和上三叠统,压力分段明显.相同的压力段在不同构造既不等时也不等深;在平面上离异常地层压力分布广泛,超高压区则分布于川西北地区,并形成两个超高压中心.整个高异常地层压力的分布虽然总体上基本一致,但在不同层位,不同时期也存在着差异.

The Sichuan basin is one of the most important petroliferous basins in China. Many abnormal pressure gas reservirs have been discovered in the west Sichuan depression of the basin. The distributing characteristics of abnormal-pressure in the depression are analysed based on the formation pressure data of more than 20 gas-bearing.structures. It is revealed that the abnormal pressure mainly occurrs in the Jurassic and Upper Triassic and can be clearly divided into several different parts in the cross sections. The corresponding parts are neither isochronous nor isobathic in the different structures. The contour maps of abnormal pressure indicate that the abnormal pressure, is widespread and the distribution patterns are similar in different stages and horizens. Futhermore, the overpressure is mainly distributed in the northen part of the depression and formed two overpressure centers.