鄂尔多斯盆地富县地区长7油层组致密砂岩成岩作用及孔隙演化  

Diagenesis and porosity evolution of Chang7tight sandstones in Fuxian area,Ordos basin

作　　者：卢杰河 王香增[3] 贺永红[3] 杨超 邓南涛 

机构地区：[1]中国科学院地质与地球物理研究所,北京100029 [2]中国科学院大学地球科学学院,北京100049 [3]陕西延长石油(集团)有限责任公司,陕西西安710075

出　　处：《东北石油大学学报》2017年第3期9-20,共12页Journal of Northeast Petroleum University

基　　金：国家自然科学基金项目(41372151);国家科技重大专项(2011ZX08005-004)

摘　　要：致密砂岩油是非常规油气勘探的热点领域。以鄂尔多斯盆地东南部富县地区长7油层组为研究对象,利用铸体薄片、扫描电镜、常规物性、X线衍射和稳定同位素等方法,分析致密砂岩的成岩作用,并对孔隙度演化进行半定量恢复。结果表明:长7油层组致密砂岩储层处于中成岩阶段A期,经历机械压实、绿泥石包膜、泥微晶方解石和亮晶方解石胶结、有机酸溶蚀、高岭石及蒙皂石向伊/蒙混层转化、少量微晶石英和石英次生加大等成岩作用。物性演化主要受机械压实、亮晶方解石胶结和有机酸溶蚀等成岩作用影响,但不同成岩作用在不同成岩时期所起作用存在差异。砂岩储层大致经历早成岩阶段A期(T_3—J_1末)、早成岩阶段B期(J_1末—K_1早)、中成岩阶段A期快速埋藏(K_1早—K_2早期)和中成岩阶段A期缓慢抬升等4个孔隙演化阶段,孔隙度从35.0%的原始孔隙度一直演化至现今6.6%。该研究结果对鄂尔多斯盆地东南部富县地区油气勘探有指导意义。Tight oil of Chang7 sandstones is an important part of petroleum exploration in Fuxian area,southeastern Ordos basin.Therefore,it is essential to study the diagenesis and porosity evolution of Chang7 tight sandstones carefully for a further petroleum exploration.Various analytical techniques were used,including thin-section petrography,SEM/EDS,measured porosity and permeability,XRD and stable isotope geochemistry,to the study of diagenesis and porosity evolution of Chang7 sandstones in this area.The result shows that Chang7 reservoir is now in the subphase A of Mesodiagenesis.The main diagenesis include compaction,cementation of grain-coating chlorite,authigenic micrite and sparry calcite,authigenic kaolinite,authigenic microquartz,authigenic quartz overgrowth,transferring from mixed-layer Illite-Smectite to Illite,and dissolution by organic acid.Reservoir quality of the studied sandstones is controlled mainly by compaction,cementation of authigenic sparry calcite and dissolution.The porosity evolution process can be divided into four stages,including subphase A of Eodiagenesis(from 195 Ma to 175 Ma),subphase B of Eodiagenesis(from 175 Ma to 115Ma),early subphase A of Mesodiagenesis(from 115 Ma to 100Ma)and late subphase A of Mesodiagenesis(from 100 Ma to present).In the first stage,porosity loss of studied sandstones from 35.0%to 17.3%,mainly controlled by compaction;in the second stage,porosity increased moderately from 17.3% to 20.3%;in the third stage,porosity loss from 20.3% to 7.0%,mainly controlled by compaction and cementation of authigenic calcite;in the fourth stage,porosity loss very slightly,cause to small variation of maximum geotempreture and maximum depth.

关 键 词：致密砂岩 致密油 成岩作用 孔隙演化 长7油层组 富县地区 

分 类 号：TE122.2[石油与天然气工程—油气勘探]