| 川西南地区下寒武统筇竹寺组页岩气纵向差异富集主控因素 |
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| 引用本文： | 王鹏威,刘忠宝,金之钧,刘光祥,聂海宽,冯动军,陈筱.川西南地区下寒武统筇竹寺组页岩气纵向差异富集主控因素[J].地球科学,2019,44(11):3628-3638. |
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| 作者姓名： | 王鹏威 刘忠宝 金之钧 刘光祥 聂海宽 冯动军 陈筱 |
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| 作者单位： | 1.页岩油气富集机理与有效开发国家重点实验室, 北京 100083 |
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| 基金项目： | 中国博士后科学基金项目2017M610150国家重大专项2017ZX05036-004-007国家自然科学基金项目41872124 |
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| 摘 要： | 川西南地区筇竹寺组发育多套富有机质页岩，但上部优质页岩的含气性明显好于下部优质页岩.应用热解实验、物性测试、全岩矿物X衍射、低温氮气吸附、氩离子抛光-扫描电镜等方法对筇竹寺组页岩地化、储层、封盖条件等开展分析，揭示筇竹寺组页岩气纵向差异富集的主控因素.研究表明，页岩气差异富集的主要控制因素为:（1）页岩有机质富集程度:筇竹寺组上部页岩段TOC含量相对较高、分布集中，下部优质页岩段TOC含量较低且分布不均、分散，从而导致页岩纵向生烃物质条件、有机质孔隙发育及微孔（比表面）的差异.（2）页岩岩矿组成及储层特征:上部优质页岩段粘土含量高且以伊蒙混层为主，有利于吸附气富集，该页岩段以有机质孔隙为主，微孔相对比较发育但孔隙度较高，下部优质页岩以粘土矿物孔、脆性矿物粒间孔及微裂缝为主，介孔相对比较发育但孔隙度较低.（3）保存条件:上页岩段顶底板发育完整且岩性致密，对页岩气层具有较好的保护作用；下页优质岩段底部存在碳酸盐岩古风化壳，底板对页岩气的保存能力薄弱.因此，TOC含量高、粘土矿物含量高、有机质孔隙发育、顶底板条件好是决定上部优质页岩段含气性优于下部页岩段的主要因素.
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| 关 键 词： | 页岩气 差异富集 主控因素 下寒武统 筇竹寺组 川西南地区 油气地质 |
| 收稿时间： | 2019-07-19 |
Main Control Factors of Shale Gas Differential Vertical Enrichment in Lower Cambrian Qiongzhusi Formation,Southwest Sichuan Basin,China |
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| Abstract: | Multiple shale gas intervals occur in the Qiongzhusi Formation in the Southwest Sichuan basin,where gas contents in upper shale section are significantly higher than those in the lower shale section. Main control factors of shale gas differential vertical enrichment in Qiongzhusi Formation were understood through analyzing geochemical feature,reservoir and sealing conditions with rock pyrolysis,physical experiements,XRD diffraction,and field-emission scanning electron microscopy. The main control factors can be summarized as follows. (1) TOC content. It is higher and enriched in the upper shale section but lower and scattered in the lower shale section,resulting in the difference in hydrocarbon generation,organic pores and micro-pore growth. (2) Mineral component and reservoir property. The upper shale is characterized by high clay mineral content,especially I/S content,which contributes to the absorbed gas. The porosity of upper shale is higher than that of lower shale,where organic pores are the main pore space. The lower shales are mainly composed of clay mineral pores,intergranular pores and micro-fractures. Compared with the lower shales,the clay mineral content in the upper shale is higher,which is dominated by I/S mixed layer that can make an important contribution to the enrichment of adsorbed gas. (3) Sealing conditions. The top and floor of the upper shale section are well developed,however,the bottom of the lower shale section is relatively weak due to the existence of paleo-weathering carbonate crust at the bottom of the shale. Therefore,high TOC,high clay mineral content and well-developed organic pores,good sealing conditions contribute to the enrichment of shale gas at upper shale section. |
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