准噶尔盆地东部地区异常压力分布特征及成因分析

GENERATION AND DISTRIBUTION OF ABNORMAL FORMATION PRESSURES IN EASTERN PART OF THE JUNGGAR BASIN

在探井实测地层压力数据的基础上 ,分析了准噶尔盆地东部地区地层压力在纵向上和平面上的分布特征 ,探讨了本区异常压力的成因。准噶尔盆地东部不同区带异常压力的特征、类型和成因都有明显的差异 :南部断褶带异常地层压力属超压型异常压力 ,主要由附加水平地应力和欠压实两种作用产生 ,其中附加地应力是最主要的成因 ;中部斜坡带异常地层压力表现为弱高压特征 ,主要由欠压实作用产生 ;北部凹陷区为负压型异常地层压力 。

More and more abnormal pressures were discovered with more intensified petroleum exploration in many localities of eastern part of the Junggar Basin. The data of tested pressures indicated that there was a clear variation about the distribution of abnormal pressures: overpressure in the South Fault Fold Belt, normal pressure and weak overpressure in the Central Slope Belt and underpressure in the North Depression. The distribution and controlling factors of the abnormal pressures were discussed, which might be resulted from disequilibrium compaction, epigenesis of clay minerals, hydrocarbon generation, aquathermal expansion and horizontal stress, etc. The main causes for generation of abnormal pressures were different in three belts: the big abnormal overpressure in the South Fault Fold Belt caused by additional tectonic stress, the normal pressures or weak abnormal overpressures in the Central Slope Belt formed by deficient compaction, and the abnormal or underpressure in the North Depression created by uplift and erosion.