致密储层差异化成岩作用及其对烃类充注过程的影响——以鄂尔多斯盆地延安地区下二叠统山西组1段为例  

Differential diagenesis of tight reservoirs and its influence on hydrocarbon charging process:Taking the first member of Shanxi Formation of Lower Permian in Yan'an area,Ordos Basin as an example

作　　者：郭兰[1] 郭顺 丁超 马志武[1] GUO Lan;GUO Shun;DING Chao;MA Zhiwu(Yanchang Oil Field Company,Yan’an 716000,China;Department of Resource Exploration and Development,Yanchang Oil(Group)Limited Liability Company,Xi'an 710075,China;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)

机构地区：[1]延长油田股份有限公司,陕西延安716000 [2]陕西延长石油(集团)有限责任公司资源与勘探开发部,陕西西安710075 [3]西安石油大学地球科学与工程学院,陕西西安710065 [4]西安石油大学陕西省油气成藏地质学重点实验室,陕西西安710065

出　　处：《天然气地球科学》2024年第10期1777-1788,共12页Natural Gas Geoscience

基　　金：陕西省教育厅项目(编号:20JS115);陕西省自然科学基础研究计划项目(编号:2017JQ4013)联合资助。

摘　　要：针对鄂尔多斯盆地非常规天然气勘探亟待解决的关键地质问题,揭示储层成岩致密化与油气充注的动态过程和关系,利用铸体薄片观察、X射线衍射、扫描电镜分析,细致对比不同类型岩石相的成岩作用类型及特征的差异性。通过流体包裹体岩相学、显微测温及激光拉曼探针测试,结合单井埋藏史和热史模拟,确定烃类充注期次和年代。综合利用成岩矿物间及与烃类间镜下结构关系观察,建立含气储层成岩—油气充注演化序列。结果表明:山西组1段主要发育2期烃类充注,第一期发生在晚三叠世—早、中侏罗世(220~170 Ma),第二期发生在晚侏罗世—早白垩世(160~100 Ma)。不同类型岩石的成岩作用、致密化过程及其与烃类充注的序列明显存在差异,富石英贫塑性岩屑砂岩在第二期烃类充注前物性较好,中成岩阶段烃类充注时边致密边成藏,富塑性岩屑砂岩早成岩阶段已基本被压实,而碳酸盐致密胶结砂岩由于方解石和菱铁矿的形成,储层致密化导致第二期烃类无法进入。深入理解致密储层差异成岩过程与油气充注关系,对筛选天然气有利区具有重要意义。In view of the key geological problems to be solved in the exploration of unconventional natural gas in Ordos Basin,the dynamic process and relationship between reservoir diagenetic densification and hydrocarbon charging are revealed.The differences of diagenesis types and characteristics of different types of rock facies are carefully compared by combining cast thin section observation,X-ray diffraction and SEM analysis.Through fluid inclusion petrography,microthermometry and laser Raman probe testing,combined with single well burial history and thermal history simulation,the hydrocarbon charging period and age were determined.The diagene⁃sis-hydrocarbon charging evolution sequence of gas-bearing reservoir is established by comprehensively using the observation of the structural relationship between diagenetic minerals and hydrocarbons under the micro⁃scope.The results show that there are mainly two periods of hydrocarbon charging in the first member of the Shanxi Formation,i.e.,the first period occurred in the Late Triassic(T3)to Early and Middle Jurassic(J1-2)be⁃tween 220 Ma and 170 Ma,and the second period occurred in the Late Jurassic(J3)and Early Cretaceous(K1)between 160 Ma and 100 Ma.The diagenesis,densification process and hydrocarbon charging sequence of dif⁃ferent types of rocks are obviously different.The quartz-rich and low-plastic lithic sandstone has good physical properties before hydrocarbon charging in the second stage,and the hydrocarbon charging in the middle diagene⁃sis stage is dense while forming reservoirs.The early diagenetic stage of the plastic-rich lithic sandstone has been basically compacted,while the carbonate dense cemented sandstone due to the occurrence of calcite and siderite,the reservoir densification prevented the entry of the second stage hydrocarbon.In-depth understanding of the relationship between differential diagenesis and hydrocarbon charging in tight reservoirs is of great practi⁃cal significance for screening favorable areas for natural gas.

关 键 词：延安地区 山西组 非常规储层 成岩演化 成藏时序 

分 类 号：TE122.1[石油与天然气工程—油气勘探]