致密砂岩储层成岩过程及其与油气充注的关系——以鄂尔多斯盆地富县地区长8储层为例  

Relationship between tight sandstone reservoir diagenetic process and hydrocanbon charging:A case study of Chang8 reservoir in Fuxian area,Ordos Basin

作　　者：丁超 郭顺 郭兰[4] 郭小波 DING Chao;GUO Shun;GUO Lan;GUO Xiaobo(School of Earth Sciences and Engineering,Xi’an Shiyou University,Xi’an 710065,China;Shaanxi Key Laboratory of Petroleum Accumulation Geology,Xi’an 710065,China;Department of Resource Exploration and Development,Shaanxi Yanchang Petroleum(Group)Co.,Ltd.,Xi’an 710065,China;Shaanxi Yanchang Oilfield Co.,Ltd.,Shaanxi Yan’an 716000,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]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)有限责任公司资源与勘探开发部,西安710065 [4]陕西延长油田股份有限公司,陕西延安716000

出　　处：《非常规油气》2024年第4期29-38,共10页Unconventional Oil & Gas

基　　金：陕西省自然科学基础研究计划项目“鄂尔多斯盆地南部奥陶系油气成藏年代及其临界转换参数”(2017JQ4013);陕西省教育厅项目“流体包裹体约束下鄂尔多斯盆地上三叠统延长组油气成藏的构造物理化学参数研究”(20JS115);西安石油大学博士科研启动基金项目“鄂尔多斯盆地南部铜川地区三叠系构造热演化史”(2014BS04)。

摘　　要：储层致密化与油气充注的时间过程及其相互关系在勘探评价中具有关键作用。将铸体薄片观察、X射线衍射、扫描电镜及核磁共振相结合,细致分析了储层砂岩成岩过程与孔隙演化。结合已有油气成藏资料,综合建立了储层砂岩埋藏-成岩-孔隙演化-油气充注的演化序列。结果表明:富县地区长8储层类型以长石砂岩和岩屑长石砂岩为主,孔喉关系复杂,为低-特低孔及特低-超低渗致密储层。早成岩阶段A期,长8储层经历机械压实(压溶)作用(Φ_(2)=21.6%),少量胶结物生成,距今192.5~152.0 Ma(J_(1)~K_(1)),Ⅰ期油气充注;早成岩阶段B期,大量胶结物生成(Φ_(3)=6.9%);中成岩阶段,距今152~126 Ma(K_(1)),Ⅱ期油气充注(主成藏阶段);晚期盆地构造抬升(Φ_(3)=10.8%),距今65.0~36.5 Ma(E_(1)),Ⅲ期油气充注。成岩过程导致油气充注的选择性与储层含油的差异性,研究成果对于寻找富县地区长8储层的“甜点区”具有重要的实际意义。The time course of reservoir densification and hydrocarbon charging and their relationship play a key role in exploration evaluation.The diagenetic process and pore evolution of the sandstone were analyzed in detail by the cast thin section observation,X-ray diffraction,SEM,and nuclear magnetic resonance.Based on the existing oil-gas accumulation data,the evolution sequence of the sandstone burial,diagenesis,pore evolution,and oil-gas charging was established comprehensively.The results show that the reservoir types of Chang8 in Fuxian area were mainly feldspar sandstone and lithic feldspar sandstone,and the pore-throat relationship was complex,and it was a tight reservoir with low to extra-low porosity and extra-low to ultra-low permeability.In the early diagenetic stage,the Chang8 reservoir in stage A experienced mechanical compaction(pressure solution)(Φ_(2)=21.6%),a small amount of cement was generated,and oil-gas were charged in stage I from 192.5 to 152.0 Ma(J_(1)~K_(1)).A large number of cements were generated in early diagenetic stage B(Φ_(3)=6.9%).In the middle rock formation stage,the large-scale oil-gas charging occurred in stage II from 152 to 126 Ma(K_(1))(main hydrocarbon accumulation stage).In the late stage of basin tectonic uplift,the oil-gas charging occurred in stage III from 65.0 to 36.5 Ma(E_(1))(Φ_(3)=10.8%).The diagenetic process leads to the selectivity of oil and gas charging and the difference of reservoir oil content,and the research results have important practical significance for finding the“sweet spot area”of Chang8 reservoir in Fuxian area.

关 键 词：富县地区 长8储层 成岩过程 孔隙演化 成藏时序 

分 类 号：P618[天文地球—矿床学]