川西坳陷须五段陆相页岩层系储层特征及对含气性的控制作用  

Reservoir characteristics and its control on gas-bearing properties of the 5th Member of the Triassic Xujiahe Formation continental shale in the Sichuan Basin of China

作　　者：陈冬霞[1] 刘雨晨 庞雄奇[1] 钟大康[1] 孟昊[1] 熊亮[2] 

机构地区：[1]中国石油大学(北京)油气资源与探测国家重点实验室,北京102249 [2]中国石化西南油气分公司勘探与开发研究院,四川成都610017

出　　处：《地学前缘》2016年第1期174-184,共11页Earth Science Frontiers

基　　金：国家重点基础研究发展计划"973"项目(2011CB201102);国家自然科学基金项目(41472110)

摘　　要：四川盆地陆相领域页岩层序发育,但其内部发育复杂的岩性及组合关系、非均质性强、储层特征不明,制约了油气勘探开发的进程。本文研究通过大量的全岩X衍射、场发射扫描电镜、高压压汞、等温吸附等实验方法,从岩石学特征、微观孔隙结构特征及物性特征等方面,对川西坳陷上三叠统须五段陆相页岩须五段储层地质特征进行研究,并分析影响储层发育的主要地质因素,同时阐明储层地质特征对天然气赋存状态和含气量大小的影响。研究结果表明:须五段储层在垂向上形成富砂型、互层型和富泥型3种叠覆式储层结构;储层均致密化严重,但泥页岩储集物性优于粉砂岩和细砂岩;水动力条件较弱的三角洲远端到滨浅湖的沉积环境和强烈的成岩作用导致须五段储层原生孔隙及粒间溶孔基本不发育,对储集性能起主要贡献的为泥页岩中发育大量片状晶间孔、有机质孔及微裂缝,因此泥页岩是须五段的最有利储层。须五段天然气为吸附气与游离气的混合气体,但以吸附气为主,吸附气含量占总含气量的84.9%。天然气赋存状态和含气量大小受控于储层的岩性、微观孔隙结构和储层的物性。Continental shale sequences are well developed in the Sichuan Basin,but the characteristic of complex petrology and lithology combination,strong heterogeneity and unclear reservoir property restricted the gas exploration and development process. Using experimental methods such as whole rock X-ray diffraction,FESEM,high pressure mercury injection,isothermal adsorption,this study investigated the reservoir geological characteristics of the 5th Member of the Triassic Xujiahe Formation continental shale according to the petrologic features,micro-pore structure and physical property,and the major geological factors influencing reservoir development.On this basis,this study also clarified the controlling effects of reservoir on the natural gas content and occurrence state.The research shows that there are three kinds of superposition-type reservoir structure in the 5th Member of the Xujiahe Formation（T3x5）in vertical,which are sand-rich type,interbedded type and mud-rich type.The densification of the reservoir is very serious,but the reservoir physical property of mudstone is better than that of siltstone and fine sandstone.The reservoirs in T3x5 have a small amount of primary and intergranular dissolution pore,which was caused by strong diagenesis and the sedimentary environment from distant part of the delta to shore shallow lake with low hydrodynamic energy.The large quantitative of flake intergranular pores,organic pore,and micro-fractures in shale make it being main contribution to the reservoir property.Besides,the continental shale gas also has mixing features of two kinds of gases,i.e.,adsorption gas and free gas.However,adsorption gas is dominant,accounting for 84.9% of the total gas content.Gas occurrence state and gas content are controlled by the reservoir lithology,microscopic pore structure and reservoir physical property.

关 键 词：陆相页岩 储层特征 川西坳陷 含气性 孔隙结构特征 

分 类 号：P618.130.21[天文地球—矿床学]