摘要
不同于海相页岩,中国陆相页岩层系源-储配置与耦合关系复杂,页岩与夹层储集特征差异显著,明确其演化规律对陆相页岩油气的勘探具有重要指导意义。利用矿物组分、有机地球化学和物性资料,结合岩心、薄片、扫描电镜观察分析,对处于不同热演化程度的鄂尔多斯盆地三叠系延长组、四川盆地侏罗系自流井组和松辽盆地白垩系营城组陆相页岩开展系统研究。通过分析页岩层系内页岩与夹层的储集空间类型与物性特征,探讨成岩-生烃协同作用下页岩与夹层孔隙形成演化过程,建立了陆相页岩和夹层孔隙的差异演化模式。结果表明:①中国陆相页岩岩相类型多样,以混合质、黏土质和粉砂质页岩为主,并常与碳酸盐岩、砂岩及凝灰岩等夹层频繁互层,岩相组合类型复杂。页岩储集空间以无机孔为主,有机孔次之,局部发育微裂缝。夹层储集空间以残余粒间(溶)孔、粒内(溶)孔和微裂缝等无机孔缝为主。②陆相页岩及夹层孔隙演化受成岩-生烃作用共同控制,页岩黏土矿物含量高、抗压实能力弱、生烃之前无机孔隙快速减少。进入生油窗后,页岩有机孔、黏土粒间/晶间孔、溶蚀孔和微裂缝发育程度逐渐增加。晚成岩阶段之前,以生油高峰为界,页岩孔隙度具有先降后升的变化规律。夹层则在压实和胶结等作用下逐渐致密,储集性逐渐变差。③延长组处于生油期,有机孔发育程度低,页岩储集条件差,砂岩夹层页岩油富集条件更优;自流井组处于成熟-高熟阶段,油、气共存,页岩有机、无机孔隙均较为发育,页岩储集条件更优,夹层主要为次要储层或隔层;营城组已进入高熟-过熟阶段,最利于页岩气和有机孔的形成,页岩储集条件最优。
Unlike marine shales,lacustrine shale sequence in China exhibits intricate source rock-reservoir configuration and coupling relationships,as well as significantly different storage characteristics between shales and their interbeds.Therefore,it is necessary to ascertain the evolutionary patterns of shales and their interbeds,which will provide critical guidance on the exploration of lacustrine shale oil and gas.Using data on mineral compositions,organic geochemistry,and physical properties,as well as data from the analyses and observations of cores,thin sections,and scanning electron microscopy(SEM)images,we conduct a comprehensive study of the lacustrine shales in the Triassic Yanchang Formation of the Ordos Basin,the Jurassic Ziliujing Formation of the Sichuan Basin,and the Cretaceous Yingcheng Formation of the Songliao Basin,which vary in thermal evolution.By analyzing the storage space types and physical properties of shales and their interbeds in these formations,we explore the formation and evolutionary processes of pores in both shales and their interbeds and establish differential evolutionary patterns of the pores.The results are as follows:(1)The lacustrine shales in China are of diverse lithofacies types,primarily consisting of mixed,clayey,and silty shales,which tend to alternate with carbonate,sandstone,and tuff,suggesting complex lithofacies assemblages.The storage spaces in the shales are dominated by inorganic pores,followed by organic pores,with microfractures developed locally.In contrast,the storage spaces in the interbeds are dominated by inorganic pores such as residual intergranular(dissolved)pores,intragranular(dissolved)pores,and microfractures;(2)The evolution of pores in the lacustrine shales and their interbeds is influenced by both diagenesis and hydrocarbon generation.The shales,with high clay content and weak anti-compaction capacity,undergo a rapid decrease in inorganic pores before hydrocarbon generation.After entering the oil generation window,these shales experience a gradual increase in organic pores,clayey intergranular/intercrystalline pores,dissolved pores,and microfractures.Prior to the late diagenetic stage,the shale porosity tends to decrease before the peak oil generation and increase afterward.In contrast,the interbeds become increasingly tight under compaction and cementation,leading to a gradual decrease in their storage capacity;(3)The Yanchang Formation shale in the oil generation window,contains underdeveloped organic pores and thus exhibits poor storage capacity.In contrast,the sandstone interbeds in the formation present more favorable shale oil enrichment conditions.The Ziliujing Formation in the mature to highly mature stage,exhibits oil and gas coexistence,characterized by well-developed organic and inorganic pores in the shale,more favorable for storage,while the interbeds serve as secondary reservoirs or barriers.The Yingcheng Formation in the highly mature to overmature stage,is the most favorable for the formation of shale gas and organic pores,boasting the optimal storage conditions in shales.
作者
胡宗全
王濡岳
路菁
冯动军
刘粤蛟
申宝剑
刘忠宝
王冠平
何建华
HU Zongquan;WANG Ruyue;LU Jing;FENG Dongjun;LIU Yuejiao;SHEN Baojian;LIU Zhongbao;WANG Guanping;HE Jianhua(State Key Laboratory of Shale Oil and Gas Enrichment Mechanisms and Effective Development,Beijing 102206,China;Key Laboratory of Shale Oil/Gas Exploration and Production Technology,SINOPEC,Beijing 102206,China;Petroleum Exploration and Production Research Institute,SINOPEC,Beijing 102206,China;Chongqing Key Laboratory of Complex Oilfield Exploration and Development,Chongqing University of Science&Technology,Chongqing 401331,China;College of Energy,Chengdu University of Technology,Chengdu,Sichuan 610059,China)
出处
《石油与天然气地质》
EI
CAS
CSCD
北大核心
2023年第6期1393-1404,共12页
Oil & Gas Geology
基金
国家科技重大专项(2017ZX05036-004)
中国石油化工股份有限公司科技攻关项目(P19017-2,P21078-9)。
关键词
孔隙演化
陆相页岩
延长组
自流井组
营城组
鄂尔多斯盆地
四川盆地
松辽盆地
porosity evolution
lacustrine shale
Yanchang Formation
Ziliujing Formation
Yingcheng Formation
Ordos Basin
Sichuan Basin
Songliao Basin
