四川盆地乐山——龙女寺古隆起震旦系气藏形成机制  

Formation Mechanism of the Sinian Natural Gas Reservoir in the Leshan-Longnvsi Paleo-uplift,Sichuan Basin

作　　者：罗冰[1] 罗文军[1] 王文之[1] 王志宏[2] 山述娇[1] 

机构地区：[1]中国石油西南油气田分公司勘探开发研究院,四川成都610000 [2]中国石油勘探开发研究院廊坊分院,河北廊坊065007

出　　处：《天然气地球科学》2015年第3期444-455,共12页Natural Gas Geoscience

基　　金：国家科技重大专项(编号:2011ZX05004-005);中国石油天然气股份有限公司重大勘探专项(编号:2012ZD01)联合资助

摘　　要：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。Sinian deep-buried carbonate gas reservoir has been discovered in the Leshan-Longnvsi Paleo-uplift, Sichuan Basin. In this paper, we discuss the formation mechanism of this reservoir based on an integrated analysis of multiple characteristics of the gas formation, including gas reservoir type, fluid nature, origin and source of gas, gas charge phase, and evolution of gas formation. Results show that the Sinian Dengying Formation gas reservoir includes diversified types, such as structural, lithological, and stratigraphic-lithological. The fluid nature varies in different gas reservoirs. The gas is of mixed origin and sourced from Sinian and Lower Cambrian rocks,and the mixed ratio varies in different reservoirs. The gas formation has subjected to three phases,including the primary formation of paleo-oil reservoir, subsequent oil-cracking, and final alteration and accumulation of gas reservoir. The gas formation has three mechanisms,including the remigration and accumulation of the cracking paleo-oil,in-situ or intact accumulation of the cracking paleo-oil, and late accumulation of dry gas. Of these three mechanisms, the second one may be the most significant for the exploration of deep-buried carbonate reservoir under high maturation condition, as exemplified by the most-recently discovered giant gas reservoir in the central basin.

关 键 词：四川盆地 乐山—龙女寺古隆起 灯影组 油裂解气 成藏演化 成藏机制 

分 类 号：TE122.2[石油与天然气工程—油气勘探]