The burial depth of the Changxing Formation in Yuanba gas field ,Sichuan Basin,is nearly 7 000 meters,the biological reef-shoals are small in scale and scattered in distribution ,and the reservoirs are small in thickness and poor in poroperm characteristics and connectivity .In addition ,the gas field has a complex gas-water contact ,and high contents of hydrogen sulfide and carbon dioxide .All of these make the gas development in the study area very difficult .For effective development of the gas reservoir ,a series of technologies has been innovatively integrated to finely characterize the reef -shoal reservoirs and their inter architecture .Firstly,the major factors controlling the development of favorable reservoirs are summarized and a reef-shoal development pattern is built based on study of stratigraphy ,sedimentary facies,modern reef-shoal deposition and diagenesis .Secondly ,under the guidance of the reef-shoal development pattern ,logging interpre-tation and reservoir identification are performed and a forward geological model is established by integration of well -seismic data,and then the reservoir distribution is predicted through sensitive seismic attributes extraction and inversion . Thirdly,the distribution of reef-shoal reservoirs is characterized by integrating geological constraints with seismic tech-niques,such as profile identification,plane constraint,3D boundary delineation,and connectivity detection.Finally,the reservoir connectivity and the spatial distribution of favorable reservoirs are analyzed .Via this workflow , three structure models of reef-shoal reservoirs are established to support the production planning and well deployment in the Changxing Formation of Yuanba gas field .%四川盆地元坝气田长兴组气藏埋深达7 000 m左右,生物礁滩规模小、分布分散,储层薄、物性和连通性差,加之气藏具有复杂的气-水关系和高含硫化氢、二氧化碳,其开发属世界级难题. 为实现该气藏规模、有效开发,作者创新和集成一系列技术,对生物礁滩储层及其内部结构进行了精细刻画. 首先,在该区层序划分、沉积微相研究和现代礁滩相研究、成岩作用研究成果基础上,总结了有利储层发育的主控因素,建立了礁滩储层发育模式. 第二,以此发育模型为指导,开展测井储层识别与物性评价,进而井-震结合建立正演地质模型,利用地震敏感属性提取及反演方法,预测了储层平面展布. 第三,采用地质约束、地震技术相结合的方法,通过剖面识别、平面约束、三维边界雕刻、礁滩体连通性检测和三维精细雕刻,精细刻画了生物礁滩储层空间展布. 最后,分析了生物礁体之间的连通性以及优势储层空间分布情况,总结建立了该区长兴组生物礁储层3种主要结构模型,为元坝长兴组气藏开方案编制与开发井部署提供了技术支持.
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