准噶尔盆地南缘异常高压及其成因机制初探

OVERPRESSURE AND ITS GENERATION IN SOUTH EDGE OF THE JUNGGAR BASIN

实测地层压力、测井及泥浆比重等资料均显示准噶尔盆地南缘具有显著的异常高压现象 ,异常高压的分布主要受地层层位的控制 ,其中又以下第三系安集海河组的控制作用最为明显。异常高压的形成主要是快速沉积、厚层泥岩的封闭作用及构造应力等因素综合作用的结果 ,而粘土矿物转化、烃类生成作用的影响则相对较小。

There were overpressures in south edge of the Junggar Basin, which could be proved by observed pressures, such as RFT and DST, and well log information, such as sonic defferential time and mud weights. The maximum value of pressure coefficient of the overpressure was 2.40 in the Well An6, and the distribution of the overpressure was controlled by the stratum, especially by the Anjihaihe Formation in age of Eogene. The overpressure was mainly in the second and third row of anticlines, and part of the Qigu anticline. The generation of overpressures might have a complicated cause, namely, a synthetic result of the rapid sedimentation in Cenozoic, the sealing of heavy mudstone, such as the Anjihaihe Formation, the percentage of mudstone in the formation being 85 2% to 99 7%, and the tectonic stresses. The role of the diagenic dehydration, hydrocarbon generation had relatively smaller effect for the overpressures.