库车坳陷迪那2气田异常高压成因机制及其与油气成藏的关系

通过对间接估算和地层测试获取的地层压力分布特征的研究，结合实际地质资料和前人最新研究成果，分析了库车坳陷迪那2气田异常高压的成因机制，并估算了主要超压机制对现今超压的贡献，探讨了异常高压形成过程及其与天然气藏形成的关系。结果表明，不均衡压实、构造应力和超压传递作用为迪那2气田异常高压的主要形成机制，其中断裂的垂向开启和褶皱形成引起的超压传递作用是最主要原因。迪那2气藏的形成与气藏内异常高压的形成具有同步性，康村期的早期油气充注时，储层基本为正常压力系统；库车沉积期快速的沉积作用产生了压实不均衡作用，形成了约5~10 MPa的过剩压力；库车组剥蚀期到第四纪，在强烈的构造挤压作用下，断裂幕式开启形成的垂向超压传递作用、褶皱形成引起的侧向超压传递作用和水平的构造应力作用，极大地增大了储层中异常压力的幅度，形成了约40~50 MPa的过剩压力，该时期为迪那2气田超高压及气藏形成的主要时期。

Genetic mechanism of overpressure and its relationship with hydrocarbon accumulation in Dina-2 gasfield,Kuqa depression

Based on the distribution of formation pressure estimated from acoustic logging data and measured with the DST/RFT method,we investigated the genetic mechanism of overpressure in the Dina-2 gasfield of the Kuqa depression in combination with practical geological data and latest research results.The contribution of main overpressure mechanisms to the present overpressure was estimated,and lastly the forming process of overpressure and its correlation with natural gas accumulation were studied as well.The results show that disequilibrium compaction,tectonic stress and overpressure transmission are the main mechanisms of overpressure in the Dina-2 gasfield,of which the overpressure transmission caused by vertical opening of faults and fold formation is the most important influence factor.The gas accumulation in reservoirs of the Dina-2 gasfield shows synchroneity with overpressure formation.Reservoirs in the Dina-2 gasfield used to have a normal pressure system during the early oil-gas charging in the Kangcun stage.Rapid sedimentation in the Kuqa Formation sedimentary stage resulted in disequilibrium compaction,which forms an excess pressure of about 5 to 10 MPa in reservoirs.Vertical overpressure transmission formed by the episodic opening of faults and lateral overpressure transmission by folds and the horizontal tectonic stress under intensive tectonic compression greatly increased the scope of the excess pressure since denudation stage of the Kuqa Formation,which makes reservoirs form an excess pressure of about 40 to 50 MPa.This stage is the major period of the extremely high overpressure formation and gas accumulation in the Dina-2 gasfield.