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以四川盆地乐山—龙女寺古隆起区古老的震旦系深层碳酸盐岩气藏为研究对象,通过系统分析气藏形成的各种特征,包括气藏类型、流体性质、天然气成因与来源、油气充注期次与成藏演化等,研究了气藏的形成模式机制。结果表明,四川盆地震旦系灯影组发育构造、岩性、地层—岩性等多类型气藏,不同气藏流体的性质存在差异。天然气为震旦系烃源岩与寒武系烃源岩混源气,不同气藏混源比例存在差异。气藏的形成经历了“三阶段”:古油藏生成、原油发生裂解、气藏调整与定型;具“三机制”:古油藏裂解异位聚集、古油藏裂解原位(就近)聚集、晚期干气聚集。对于类似于研究区这种高演化阶段的深层碳酸盐岩气藏,古油藏裂解原位聚集机制可能是气藏形成与保存的最有利模式,最近勘探取得重大突破的川中地区灯影组大型气藏即属于这种模式机制。
Taking the ancient Sinian deep carbonate reservoir in the Leshan-Longnupsi paleo-uplift area of Sichuan Basin as the research object, various characteristics of gas reservoir formation, such as gas reservoir types, fluid properties, gas genesis and source , Oil and gas filling period and hydrocarbon accumulation and evolution, studied the formation mechanism of gas reservoir. The results show that Sinian Dengying Formation in Sichuan Basin has many types of reservoirs such as structure, lithology, stratigraphy and lithology, and the properties of fluids in different gas reservoirs are different. Natural gas is a mixed source gas between Sinian source rocks and Cambrian source rocks. There are differences in the proportions of mixed sources between different gas reservoirs. The formation of gas reservoirs has experienced “three stages”: the formation of ancient reservoirs, the cracking of crude oil, the adjustment and stereotypes of gas reservoirs; the “three mechanisms”: ectopic aggregation of ancient reservoirs and ancient fractures of reservoirs (Nearby) gathered, late dry gas gathered. For deep carbonate reservoirs similar to the high evolution stage of the study area, the mechanism of in situ accumulation of paleo-reservoirs may be the most favorable model for the formation and preservation of gas reservoirs. Recently, Gas reservoir belongs to this mode mechanism.