四川盆地侏罗系自流井组大安寨段陆相页岩油气地质特征及成藏控制因素

Geological characteristics and controlling factors of hydrocarbon accumulation in terrestrial shale in the Da'anzhai Member of the Jurassic Ziliujing Formation, Sichuan Basin

孙莎莎 董大忠 李育聪 王红岩 施振生 黄世伟 昌燕 拜文华

Shasha Sun Dazhong Dong Yucong Li Hongyan Wang Zhensheng Shi Shiwei Huang Yan Chang Wenhua Bai

四川盆地侏罗系陆相油气勘探过去主要聚焦在构造-裂缝型常规油气和介壳灰岩及砂岩致密油气上，为实现侏罗系油气重大新突破，思路需要向页岩油气转变。在分析自流井组大安寨段陆相页岩油气的分布、生烃、物性和保存等地质特征基础上，认为大安寨段具备形成大规模页岩油气成藏地质特征，提出3项成藏控制因素。大安寨段二亚段暗色页岩作为页岩油气的供烃源岩，油气显示丰富，页岩厚度在20~80 m，整体分布面积广、厚度大、连续稳定，孔缝发育、物性好，处于中-高成熟热演化阶段，有区域性致密顶底板灰岩封闭的超压页岩油气藏。半深湖-深湖亚相、致密灰岩顶底板与高孔隙储层、中-高成熟热演化阶段这3项因素共同控制自流井组大安寨段页岩油气的生成、储集和富集。

Hydrocarbon exploration in the terrestrial Jurassic system of Sichuan Basin has been focused on conventional tectonically fractured reservoirs and unconventional coquina and tight sandstone reservoirs.However, shale reservoirs are regarded as the new focal point for making significant breakthroughs in the system of the basin.Based on an analysis of the distribution, generation, reservoir properties and preservation conditions of the terrestrial shale oil/gas in the Da'anzhai Member of Ziliujing Formation, we conclude that the member is favorable for a large-scale shale oil and gas accumulation in terms of its geological features and that three factors serve to control the accumulation.Geologically, the 20-80 m thick dark shale with oil and gas shows in the 2 sub Da'anzhai Member is both excellent source rock and over-pressured oil/gas reservoir sandwiched between cap and bottom tight limestones with its wide and continuous distribution, large thickness, well-developed pores and fractures, good physical properties, and medium-high maturity.The three factors including the semi-deep and deep lacustrine sub-facies, high-porosity reservoirs between the top and bottom limestones and medium-high maturity, jointly control the generation, preservation, enrichment of oil and gas in the shale.

10.11743/ogg20210111