| 浅谈陆相湖盆深水重力流沉积研究中的几点认识 |
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| 引用本文： | 杨田,操应长,田景春.浅谈陆相湖盆深水重力流沉积研究中的几点认识[J].沉积学报,2021,39(1):88-111. |
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| 作者姓名： | 杨田 操应长 田景春 |
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| 作者单位： | 1.成都理工大学沉积地质研究院，成都 610059 |
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| 基金项目： | 国家自然科学基金项目;2019年中国石油科技创新基金研究项目 |
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| 摘 要： | 与海相盆地重力流沉积研究理论的快速发展相比，陆相湖盆重力流沉积的相关认识还存在着一定差距。综合国内、外重力流沉积相关研究成果，总结湖盆重力流沉积的相关认识，以明确湖盆重力流沉积研究中存在的不足。增强不同术语内涵及相互关系的理解、增加不同术语的解释说明，是减少术语混淆的有效途径；流体转化、流态转化和润滑作用是湖盆重力流搬运的主要动力学过程；受阻沉降、湍流抑制和牵引毯作用是湖盆重力流沉积物沉降的重要动力学过程。沉积物再搬运、洪水持续供给、漂浮羽流卸载是陆相湖盆重力流沉积主要的成因机制；重力流沉积相域类型、块状砂岩内部沉积特征和逆正粒序沉积特征精细解析可揭示重力流沉积成因。超临界浊流侵蚀作用形成重力流水道，盆地外部因素主控重力流物质成分和来源，盆地内部因素主控重力流分异效率，其综合表现形式即“源—汇”系统控制下的重力流砂体形成演化过程。洪水持续供给成因重力流沉积模式以重力流水道—堤岸沉积、水道—朵叶转换带和朵叶沉积依次过渡构成其典型沉积构型要素组合；沉积物再搬运成因沉积模式以三角洲前缘垮塌带、混杂沉积和朵叶沉积依次过渡构成其典型沉积构型要素组合。湖盆重力流沉积是非常规油气赋存的重要场所，流体转化成因的细粒沉积具有易于油气生成和富集，且易于压裂的先天优势，可能是页岩油气中的“甜点”区发育的优势沉积岩相组合类型。
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| 关 键 词： | 搬运过程 沉降过程 成因机制 沉积模式 浊流 碎屑流 重力流沉积 非常规油气 陆相湖盆 |
| 收稿时间： | 2020-02-26 |
Discussion on Research of Deep-water Gravity Flow Deposition in Lacustrine Basin |
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| YANG Tian,CAO YingChang,TIAN JingChun.Discussion on Research of Deep-water Gravity Flow Deposition in Lacustrine Basin[J].Acta Sedimentologica Sinica,2021,39(1):88-111. |
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| Authors: | YANG Tian CAO YingChang TIAN JingChun |
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| Institution: | 1.Institute of Sedimentary Geology, Chengdu University of Technology, Chengdu 610059, China2.State Key Laboratory of Oil and Gas Reservoir Geology and Exploitation ( Chengdu University of Technology), Chengdu 610059, China3.School of Geosciences, China University of Petroleum (East China), Qingdao, Shandong 266580, China |
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| Abstract: | In the last few years,great progress has been achieved in the understanding of gravity-flow deposits in marine basins,but the study of gravity-flow deposits in lacustrine basins lags far behind.Research on gravity-flow deposits in China and globally are summarized here to clearly illustrate the shortcomings of gravity-flow deposit research for lacustrine basins.Clarifying meanings and relationships between different terminologies,as well as detailed interpretation,are reliable ways of reducing terminology confusion.Gravity-flow transformation,flow-state transformation,and lubrication are mainly dynamic processes of gravity flow.Transportation,hindered settling,turbulence damping,and traction carpet are dynamic processes of gravity flow,whereas settling,sediment re-transportation,sustained supply from flooding rivers,and the settling of buoyant plumes,are the main mechanisms of gravity flow in a lacustrine basin.Comprehensive analysis of detailed facies-tract types,analysis of the internal structure of massive sandstone,and analysis of the characteristics of inverse-then-normal sequences are all important means of revealing the genesis of gravity-flow deposits.Gravity-flow channels are formed by erosion due to supercritic ally turbid currents.The material composition and source of gravity flow are dominated by factors external to the basin,while the effective segregation of gravity flow types is dominated by internal basin factors.The integration of internal and external basin factors are termed "source-to-sink" systems,covering the overall gravity-flow evolutionary processes.The depositional model of gravity flow caused by sustained supply from flooding rivers comprises gravity-depositional elements,which include channel-levee deposits,channel and lobe transition zones,and lobe deposits.Depositional models of gravity flow due to sediment re-transportation contain gravity-depositional elements,such as sediment failure at the delta front,chaotic deposits,and lobe deposits.Gravity-flow deposits are the main reservoirs for unconventional oil and gas in a lacustrine basin.The fine-grained deposits resulting from flow transformation have the potential for oil and gas generation and enrichment-and,at the same time,they are appropriate for hydraulic fracturing,which makes them the foremost lithofacies association for sweet-spot development in shale oil and gas exploration. |
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| Keywords: | transportation processes settling processes genesis mechanism deposition model turbidity currents debris flows gravityflow deposits unconventional oil and gas lacustrine basin |
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