石柱地区上组合油气保存条件分析

石柱地区上组合气藏具备上三叠统下侏罗统、中三叠统巴东组和下三叠统嘉陵江组3套区域盖层,以及气层上覆的直接盖层;石柱复向斜盖层的宏观封闭性能较好,直接盖层的微观封闭性能也较优越;地层水化学性质纵向具分带性、横向具分区性;复向斜内受渗入水影响较弱,主要表现为沉积承压水动力系统。区内断层的封闭性主要依赖于岩性对置封堵,泥岩滑抹作用较弱。控制油气保存条件的主要是水动力条件和断裂分布及其封堵条件,划分出了有利、较有利的油气保存区域。

Conditions for Hydrocarbon Preservation in the Upper Assemblage of Shizhu Area

There exist 3 sets of caprocks of upper Triassic-lower Jurassic,mid Triassic Badong Formatin and lower Triassic Jialingjiang Formation and the direct caprock of overlapping gas reservoir.The macroscopic seal of synclinorium caprock is better in Shizhu Area,while the microscopic seal of the direct caprock is more superior,the chemical property of formation water is zonation vertivally and partitioning longitudinally,the synclinorium is weakly influenced by invasion water,which presents a depositionally pressureized hydrohynamic system.The seal in the fault depends mainly on opposed lithologic plugging,mudstone sliding is weaker.The key controlling the reservoir preservation condition is the hydrodynamic condition,fault distribution and seal-off condition.The areas of beneficial and more beneficial for oil and gas preservation are established.