柴达木盆地尕斯断陷的油气生成与初次运移

Modelling Oil Generation and Primary Migration in Gasi Faulted Depression of Caidam Basin

利用岩石学、地层学和有机地球化学资料,对柴达木盆地尕斯断陷下第三系主力生油层下干柴沟组上段(E_(3×g)~2)进行了生烃史与石油初次运移的定量模拟。分析了该生油层的埋藏受热史和有机质生烃史,并计算了生油层孔隙流体压力、孔隙度、含油饱和度及排烃系数。研究表明,在加热速度远大于1℃/my的尕斯断陷,用基于阿仑尼斯方程的生烃化学动力学模式比用Loptin法能更准确地计算生烃量。石油初次运移只有在生油层的含油饱和度大子5%这一临界值时才能发生。通过对切2井、跃110井和红参2井的生油层(E_(3×g)~2)模拟,表明尕斯断陷跃进地区与切克里克地区的生油岩已成熟,并达到了排烃门限;而红柳泉地区的生油岩则没有达到排烃门限。

The modelling of oil generation and primary migration for Oligocene source rocks (E^2_(3×g) in Gasi faulted depression of Caidam Basin is discussed with the data about petrology, stratigraphy, and organic geochemistry. The main attention is paid to the reestablishment of its heat and oil generation history, and the calculation of its overpressure, porosity, oil saturation and rate of expelled oil It is suggested TTI_(ARR) method models the oil generation more accurately than the Lopatin method in such area of heating rate significantly greater than 1℃/my as this region(2.9℃ /my). Primary oil migration can be occured once the oil saturation is higher than a critical level(5%). From the modelling source rocks in the wells of Qie 2, Yue 110 and Hongchan 2, the results indicate that the oil saturation of the source rocks in Yuejing and Qiekelike have excessed the irreducible level, but that in Hongliuquan has not.