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海相页岩层系内部成藏条件与聚油机理的 分层(段)研究

作    者:谷 峰, 李又武, 李乐忠, 唐 颖, 张 越, 吴晓丹
单    位:中海石油气电集团有限责任公司
基金项目:--
摘    要:
Toolebuc组页岩为澳大利亚一套海相灰质页岩,具有明显分层(段)特征。综合利用地球化学分析、扫描电镜、能谱分析、岩相划分与对比等手段对页岩成藏条件的差异进行了精细研究。研究表明: ① Toolebuc组页岩有机质丰度高,已进入低成熟演化阶段,中段含碳屑页岩TOC最高,为主力生烃层段; ② 上段灰质页岩的微观孔隙类型最为丰富,发育孔径大且连通性好的生物骨架粒间孔、钙质溶孔和有机质溶孔,为页岩油优势储集层段; ③ 当中段、上段与上覆盖层的岩相组合为“页岩-灰质页岩-页岩”时,对页岩油封盖最为有利。通过对Toolebuc组页岩滞留烃的富集因素分析,上、中、下3段有效源岩有机碳下限分别为4%、7%和5%,认为上段灰质页岩更利于烃类滞留,中段滞留烃所需有机碳最高,有效烃源岩比例超过60%,排烃最为显著。Toolebuc组页岩整体具有多层段供烃、优势空间储集、差异化封盖、有效源岩滞留的成藏特征,页岩层系内成藏条件的差异决定了页岩油的分布与富集特征,岩相是生储盖差异的决定性因素。
关键词:澳大利亚; Toolebuc组; 页岩油; 灰质页岩; 成藏差异; 滞留烃

The stratified research of reservoir-forming conditions and oil accumulation mechanism in marine shale: a case study of Toolebuc shale, Australia

Author's Name: GU Feng, LI Youwu, LI Lezhong, TANG Ying, ZHANG Yue, WU Xiaodan
Institution: CNOOC Gas&Power Group Ltd.
Abstract:
Toolebuc shale is a set of marine limy shale with obvious stratification(section) characteristics in Australia. In this paper, geochemical analysis,scanning electron microscope,energy spectrum analysis,lithofacies division and correlation were used to study the differences of oil accumulation conditions of shale reservoir of Eromanga Basin. It is concluded as follows: (1)the TOC of Toolebuc shale is high in general, and has reached low-maturity stage, the dark gray carbonaceous shale of middle section with the highest TOC is the main hydrocarbon generation layer; (2)the upper limy shale has the most abundant types of micropores, with the development of intergranular pores in skeleton of fossils, calcareous dissolved pores, and organic acid dissolved pores with large pore size and good connectivity, which are the dominant reservoir of shale oil; (3)when the lithofacies of the middle section, the upper section and the upper overburden are combined as “mudstone-limy shale-shale”, it is the most favorable sealing cap for shale oil. Through the analysis of S1 and TOC of Toolebuc shale, the lowest limit of TOC of effective source rocks in upper mumber, middle mumber and lower mumber are 4%,7% and 5% respectively, and it is believed that the upper limy shale is more conducive to hydrocarbon retention, the TOC required for hydrocarbon retention is the highest, the proportion of effective source rocks exceeds 60%, and the hydrocarbon expulsion is the most significant in the middle stage. Toolebuc shale has the characteristics of oil accumulation with hydrocarbon supplying in multiple sections, dominant lithofacies reservoiring, differential sealing and retention in effective source rock. The distrubution and accumulation of shale oil are determined by the differences of reservoir forming conditions in shale strata and lithofacies is the main controlling factor of the difference between source, reservoir and cap.
Keywords: marine limy shale; accumulation conditions; hydrocarbon retention; Eromanga Basin; Australia
投稿时间:2017-03-01  
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