川中地区侏罗系自流井组大安寨段黑色页岩孔隙微观特征及主控因素  

Microscopic pore characteristics and controlling factors of black shale in the Da’anzhai Member of Jurassic Ziliujing Formation,central Sichuan Basin

作　　者：祝海华[1] 陈琳 曹正林 王明磊[3] 洪海涛[2] 李育聪 张芮 张少敏 朱光仪 曾旭[3] 杨巍[1] Zhu Haihua;Chen Lin;Cao Zhenglin;Wang Minglei;Hong Haitao;Li Yucong;Zhang Rui;Zhang Shaomin;Zhu Guangyi;Zeng Xu;Yang Wei(School of Geosciences and Technology,Southwest Petroleum University,Chengdu,Sichuan 610500,China;Research Institute of Exploration and Development,Southwest Oil&Gas Field Company,PetroChina,Chengdu,Sichuan 610041,China;Research Institute of Petroleum Exploration&Development,PetroChina,Beijing 100083,China)

机构地区：[1]西南石油大学地球科学与技术学院,四川成都610500 [2]中国石油西南油气田分公司勘探开发研究院,四川成都610041 [3]中国石油勘探开发研究院,北京100083

出　　处：《石油与天然气地质》2022年第5期1115-1126,共12页Oil & Gas Geology

基　　金：中国石油-西南石油大学创新联合体科技合作项目(2020CX050103);国家自然科学基金项目(4177021173)。

摘　　要：为研究川中地区侏罗系自流井组大安寨段页岩油储层储集空间特征及控制因素,利用电镜、显微荧光、物性分析、氮气吸附、有机碳及热解等测试手段,开展页岩层系的储集空间、物性、含油性分析,并讨论了微观特征的控制因素。结果表明:①大安寨段页岩油储层储集空间包括微裂缝和孔隙,微裂缝主要为页理缝和介壳方解石解理缝,孔隙以粘土孔隙为主,其次为介壳方解石晶间孔、自生石英晶间孔,少量有机质孔、黄铁矿晶间孔。②大安寨段页岩油储层具有孔径-孔隙度负相关特征,即页岩孔隙度高(平均5.69%),粘土孔隙是主要孔隙类型,孔径小,孔隙与页理缝组成水平孔缝系统;介壳灰岩孔隙度低(平均3.27%),介壳方解石、石英晶间孔比例增加,孔径大,孔隙与解理缝形成网状的孔缝系统。③油相微观赋存具有较强非均质性,表现为富有机质页岩段含油性(热解游离烃含量S_(1)、油饱和度指数OSI)好,但油相分散分布于粘土微小孔隙中,显微荧光弱,流动性差;孔径大的介壳方解石/石英晶间孔隙、解理缝以及页理缝中烃类更富集,显微荧光强。④微裂缝对烃类的微观富集至关重要。油气生成之后优先进入页理缝,并在页理缝附近的介壳方解石孔缝系统中富集,而距离页理缝较远的介壳方解石孔隙含油性变差,建议以孔径和微裂缝发育程度作为大安寨段页岩油有利层段优选的关键参数。The reservoir space characteristics and controlling factors of shale oil reservoirs in the Da’anzhai Member of the Jurassic Ziliujing Formation,central Sichuan Basin,are analyzed based on the pore types,porosity and oil content data gathered from thin sections,SEM images,microfluorescence responses,porosity and permeability tests,N2 adsorption behaviour,and organic carbon measurements as well as Rock-Eval pyrolysis on samples from the member.The results show that:①The reservoir space consists of microfractures and pores.The microfractures are mainly lamellation fractures and shell calcite cleavage fractures,while the pores are mainly clay pores followed by shell calcite and authigenic quartz intercrystalline pores together with a small number of organic pores and pyrite intergranular pores.②A negative correlation between pore size and pore volume is observed in the shale oil reservoirs in the member.The shale is high in porosity(averaged at 5.69%)and dominated by clay pores that are small in size and tend to form horizontal pore-fracture system with laminated fractures;the intercalated shell limestone is low in porosity(averaged at 3.27%)though it contains more shell calcite and authigenic quartz intercrystalline pores with large pore size that are likely to form pore-fracture networks with cleavage fractures.③The micro occurrence of oil in the reservoirs is highly heterogenous.The organic rich shale intervals have high oil content(S_(1)and OSI)but with oil widely dispersed in micro clay pores,they give out weak fluorescence and have low mobility.While the larger shell calcite/quartz intergranular pores,shell calcite cleavage and lamination fractures are hosting more oil and give out strong fluorescence.④Micro-fractures are essential to the accumulation of hydrocarbon.Hydrocarbons expelled from kerogen would preferentially migrate into lamellation fractures and accumulate in shell calcite/quartz intergranular pores around the lamellation fractures,resulting in low oil content in shell calcite pores that

关 键 词：微裂缝 孔隙特征 孔缝系统 页岩油 大安寨段 侏罗系 四川盆地 

分 类 号：TE122.2[石油与天然气工程—油气勘探]