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介绍了从古流体的角度对海相碳酸盐岩区油气保存条件研究的新思路、方法、原理和实例。利用古流体对保存条件进行动态评价,是在建立流体活动事件序列的基础上,对每一期流体尤其是那些关键性流体进行地质与地球化学示踪,确定古油气藏盖层以上的地层中是否有来自于古油藏或古气藏中的流体,或者储层中是否有大气淡水的注入,从而就盖层对流体的封盖能力进行评价。采用这一方法,对川中安平1井、高科1井和合12井的油气保存条件进行了分析,恢复了古油气藏的形成-破坏过程。研究表明,研究区生油窗之前下组合内部的流体相互连通,下组合内部的泥质岩和膏盐岩对下伏流体不具有封隔能力。生油窗期、生气窗期保存条件相对较好,形成了古油藏和古气藏。燕山期-喜马拉雅期以来的隆升,使保存条件变差、热裂解气逸散和水溶气脱溶;古气藏之中的盐水流体由下向上发生垂向流动迁移到上覆寒武系-二叠系之中,古气藏被完全破坏。向上运移的热裂解气和水溶气有可能在上覆三叠系海相碳酸盐岩中重新聚集成藏。
The new ideas, methods, principles and examples of oil and gas storage conditions in marine carbonate area from the paleo-fluidic point of view are introduced. The dynamic evaluation of the preservation conditions by using paleo-fluid is based on the sequence of fluid activity events. Geological and geochemical tracing of each fluid, especially those critical fluids, is performed to determine the formation above the caprock of the ancient oil-gas reservoir Whether there is fluid from an ancient or paleo-gas reservoir or whether fresh air is injected into the reservoir to assess the ability of the cap to seal the fluid. By using this method, the hydrocarbon reservoirs in Anping 1, Gaoke-1 and Hehe 12 wells in central Sichuan were analyzed to restore the formation-destructive process of paleo-oil reservoirs. The results show that the fluid inside the lower combinatorial reservoir before the oil production window in the study area are interconnected, and the mudstone and gypsum salt rock in the lower combinatorial assemblage have no sealing ability to the underlying fluid. During the oil-generating window and the angry window, the preservation conditions are relatively good, forming the paleo-oil reservoir and the paleo-gas reservoir. The Yanshanian-uplift since the Himalayan period has worsened the preservation conditions, dissipated pyrolytic gas and dissolved water, and the saline fluid in the paleo-gas reservoir migrated vertically from below to above the Cambrian- Among the Permian, the ancient gas reservoir was completely destroyed. Upward migration of pyrolysed gas and water-soluble gas may re-accumulate in the overlying Triassic marine carbonate rocks.