库车坳陷天然气高效成藏过程分析

塔里木盆地库车坳陷具备大中型天然气藏形成的基本地质条件。其中,三叠-侏罗系烃源岩不仅累积生气强度大,而且新近纪以来的快速生、排气过程,形成了一类高效气源灶,为形成克拉2型的高效天然气藏起到了关键作用。其次,新近纪以来,库车坳陷山前冲断带受挤压作用发生了强烈的构造变形,盐下白垩系-侏罗系发生垂向叠复使地层出现体积增容。在优质盖层保护下,地层增容产生构造抽吸作用,是克拉2型高效天然气藏形成的重要途径。通过生烃动力学及构造物理模拟实验,证实了这些新的认识,并进一步揭示了库车坳陷侏罗系烃源岩的有效生气及天然气的有效运移聚集成藏的过程。

Analysis of highly efficient gas reservoiring process in Kuqa depression

Kuqa depression in Tarim basin has the basic geologic conditions to form medium and large gas pools. The Triassic-Jurassic source rocks not only have very large cumulative gas generating intensity, but also have experienced a very rapid gas generating and discharging process since Neogene; thus they have become highly efficient gas kitchens and played a key role in the formation of Kela 2 type high efficient gas pools. The piedmont thrust zone in Kuqa depression has been strongly deformed due to the compression since Neogene. Vertical superimposition of Cretaceous-Jurassic strata below the halite resulted in increment of rock volume. Being sealed by good caprock, the rock volume enlargement would lead to structural swabbing, an important process for the formation of Kela 2 type high efficient gas pools. Simulation experiments of hydrocarbon-generating kinetics and tectophysics have proved these new understandings and further revealed the effective gas generation of Jurassic source rocks and effective gas migration and accumulation process in Kuqa depression.