准南地区异常地层压力发育特征及形成机理

根据实测渗透层压力数据、计算的泥岩压力纵向分布、预测的不同层位异常压力分布，分析了准噶尔盆地南部砂、泥岩地层异常高压的分布特征。在综合压实曲线的对比基础上，分析了异常地层压力的成因。凹陷内渗透层异常高压非常发育，泥岩的地层压力分布既可与砂岩的实测压力相似，也可出现小于砂岩实测压力的现象，说明砂岩中的异常压力并非全由泥岩的欠压实作用引起。通过综合压实曲线的对比，可以确认不同井处的超压是否主要由压实作用引起。研究区异常压力的成因主要有压实与排水不平衡、构造挤压、高流体势承压、断层对水动力的垂向贯通，在不同地区，这4个因素所起的作用大小有所差别。概括而言，西部地区超压的成因以压实作用为主，东部则与构造挤压、断层活动导致的水动力贯通等有关。

The development features and formation mechanisms of abnormal high formation pressure in southern Junggar region

Abnormal high formation pressure is an important component of fluid dynamics in petroliferous basins, and relates closely with origin, migration and accumulation of hydrocarbon, and drilling engineering as well. According to data of measured pressure in reservoir bed, vertical distribution of calculated pressure in mudstone, and plans of estimated overpressure in different strata, it is analyzed that the distribution features of abnormal high formation pressure in sandstone and mudstone in the southern Junggar basin, and the cause mechanisms of overpressure mainly by contrast of synthetical compaction curves. It is detected that the overpressure developed well in sandstones in sag, and the distribution of pressure in mudstone is either similar with measured pressure in sandstone, or is smaller than the latter, the abnormal high pressures in sandstones is not completed aroused by under-compaction in mudstone. By contrast of synthetical compaction curves in mudstone, it is affirmed whether or not the overpressure in different wells is caused by compaction. It is summed up that cause of abnormal formation pressure include factors of disequilibrium between compaction and expulsion of water in mudstone, tectonic compression, bearing pressure by high fluid potential, vertically hydrodynamic run-through by fault, etc, and their actions are of distinction respectively among different areas. It is generalized that the formation of abnormal pressure in western area is caused mainly by undercompaction, and in eastern area is from tectonic compression, hydro-dynamic transmission throngh faults, and so on.