鄂尔多斯盆地延安地区二叠系山西组页岩气源储特征及聚集规律  

Source-reservoir characteristics and accumulation rules of shale gas of Permian Shanxi Formation in Yan’an area,Ordos Basin

作　　者：段逸飞 赵卫卫 杨天祥[3] 李富康 李慧 王嘉楠 刘钰晨[1,2] DUAN Yifei;ZHAOWeiwei;YANG Tianxiang;LI Fukang;LI Hui;WANG Jianan;LIU Yuchen(School of Earth Sciences and Engineering,Xi’an Shiyou University,Xi’an 710065,China;Shaanxi Key Laboratory of Petroleum Accumulation Geology,Xi’an Shiyou University,Xi’an 710065,China;Gas Field Company,Shaanxi Yanchang Petroleum(Group)Co.,Ltd.,Yan’an 716000,Shaanxi,China;Natural Gas Research Institute Branch,Shaanxi Yanchang Petroleum(Group)Co.,Ltd.,Xi’an 710065,China)

机构地区：[1]西安石油大学地球科学与工程学院,西安710065 [2]西安石油大学陕西省油气成藏地质学重点实验室,西安710065 [3]陕西延长石油(集团)有限责任公司气田公司,陕西延安716000 [4]陕西延长石油(集团)有限责任公司天然气研究院分公司,西安710065

出　　处：《岩性油气藏》2024年第3期72-83,共12页Lithologic Reservoirs

基　　金：国家科技重大专项“陆相页岩储气机理与储层精细描述研究”(编号:2017ZX05039-001-002)资助。

摘　　要：鄂尔多斯盆地延安地区二叠系山西组页岩气勘探潜力较大。通过分析钻井、录井以及测井资料,结合泥页岩样品的分析化验资料,深入分析了延安地区二叠系山西组页岩气源储特征及成藏过程,并探讨页岩气聚集机理。研究结果表明:(1)鄂尔多斯盆地延安地区二叠系山西组大面积分布的泥页岩有机碳(TOC)含量较高,平均质量分数为2.12%,干酪根类型主要为Ⅲ型,Ro为2.0%~3.7%,处于高成熟—过成熟阶段,为优质烃源岩。(2)研究区山西组泥页岩矿物组成整体上具有富黏土特征,黏土矿物平均质量分数为56.7%,有利于吸附气的赋存;主要发育无机矿物孔、有机孔和微裂缝3种储集空间类型;岩石含气性受不同岩性组合的影响而差异较大,山2段相较于山1段具有较高的含气量(平均质量体积为1.38 m3/t)。按照源储配置关系,可划分为厚层泥页岩夹薄砂层、泥页岩与粉砂岩和细砂岩互层、泥页岩与煤层混层3种类型,不同的源储配置具有不同的含气特征。(3)研究区页岩气主要以吸附态、游离态赋存,在成藏过程处于动态平衡的状态,随着地层条件的变化而不断转化。其聚集过程可分为3个阶段:早侏罗世,有机质开始生成气态烃,页岩气开始吸附聚集;中—晚侏罗世,气态烃大量生成膨胀造隙,气态烃排出,裂缝关闭,循环运移聚集;早白垩世,有机质达到高—过成熟阶段,进入最后一个生排烃时期,直至地层抬升,生烃终止。泥页岩良好的封盖作用为页岩气藏的形成提供了坚实的保障。Permian Shanxi Formation has great exploration potential for shale gas in Yan’an area of Ordos Basin.By analyzing drilling,mud-logging and wire-logging data,combined with the analysis and laboratory data of shale samples,the source-reservoir characteristics and accumulation process of shale gas of Permian Shanxi Formation in Yan’an area were analyzed,and the accumulation mechanism of shale gas was discussed.The results show that:(1)The organic carbon(TOC)content of shale of Permian Shanxi Formation in Yan’an area of Ordos Basin is relatively high,with an average mass fraction of 2.12%.The main type of kerogen is typeⅢ,with Ro ranging from 2.0%to 3.7%.It is in the high to over mature stage and high-quality source rocks.(2)The mineral composition of the shale of Shanxi Formation in the study area seems to be rich in clay,with an average mass fraction of clay minerals of 56.7%,which is conducive to the occurrence of adsorbed gas.There are mainly three types of reservoir spaces:inorganic mineral pores,organic pores,and micro-fractures.The gas content of rocks varies greatly due to the influence of different lithology combinations.The Shan 2 member has a higher gas content than Shan 1 member(with an average mass volume of 1.38 m3/t).According to different lithology combinations,the source-reservoir configuration of shale gas of Shanxi Formation can be divided into three types:thick shale interbedded with thin sand layer,shale interbedded with siltstone and fine sandstone,and shale mixed with coal seam.Different source-reservoir configurations have different gas-bearing characteristics.(3)The shale gas is mainly in adsorbed state and free state in the study area,and is in a dynamic equilibrium state during the accumulation process,continuously transforming with the change of formation conditions.The accumulation process can be divided into three stages:In Early Jurassic,organic matter began to generate gaseous hydrocarbons,and shale gas began to adsorb and accumulate;During Middle-Late Jurassic,a large number o

关 键 词：页岩气 源储配置 吸附态 游离态 聚集规律 封盖作用 山西组 二叠系 延安地区 鄂尔多斯盆地 

分 类 号：TE122.1[石油与天然气工程—油气勘探] P618.13[天文地球—矿床学]