石油与天然气地质 ›› 2018, Vol. 39 ›› Issue (2): 229-238.doi: 10.11743/ogg20180203

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重庆下古生界页岩顺层滑脱变形域的形成及其地质意义

岳锋1,2, 李永臣3, 赵宝山3, 曾祥亮2   

  1. 1. 甘肃省交通规划勘察设计院股份有限公司, 甘肃 兰州 730030;
    2. 重庆地质矿产研究院, 重庆 400042;
    3. 中国石油 煤层气有限责任公司, 北京 100028
  • 收稿日期:2017-02-06 修回日期:2018-03-12 出版日期:2018-04-28 发布日期:2018-05-16
  • 第一作者简介:岳锋(1986-),男,工程师,构造地质学。E-mail:lenyue860612@163.com。
  • 基金项目:
    国家重点基础研究发展计划(973计划)项目(2012CB214705-05);重庆市社会事业与民生保障科技创新专项(cstc2017shmsA90003);重庆市国土房管局科技计划项目(KJ-2015014)。

Bedding decollement deformation domain in the Lower Paleozoic shales in Chongqing:Formation and geological significance

Yue Feng1,2, Li Yongchen3, Zhao Baoshan3, Zeng Xiangliang2   

  1. 1. Gansu Province Transportation Planning, Survey & Design Institute Co., Ltd., Lanzhou, Gansu 730030, China;
    2. Chongqing Institute of Geology and Mineral Resources, Chongqing 400042, China;
    3. PetroChina Coalbed Methane Co., Ltd., Beijing 100028, China
  • Received:2017-02-06 Revised:2018-03-12 Online:2018-04-28 Published:2018-05-16

摘要: 在野外露头和岩心观察基础上,通过力学分析,对重庆下古生界页岩中顺层滑脱变形域的类型、特征及其形成进行了研究,并结合页岩气勘探实践,对其地质意义进行了探讨。顺层滑脱变形域包括挤压型和重力型两类。挤压型顺层滑脱变形域形成时水平挤压构造应力占主导地位,岩层发生“逆断层”运动;重力型顺层滑脱变形域形成时上覆地层压力占主导地位,岩层发生"正断层"运动。挤压型顺层滑脱变形域地层变形相对较强,影响范围相对较大。埋藏深度和岩层倾角是控制同一地区同一页岩层中顺层滑脱变形域形成的关键地质要素。页岩埋深越大,形成挤压型顺层滑脱变形域时的临界岩层倾角越大,而形成重力型顺层滑脱变形域的临界岩层倾角则越小。重力型顺层滑脱变形域破坏页岩气保存条件。背斜构造部位挤压型顺层滑脱变形域所形成的顺层破碎带和网状裂缝系统是页岩气重要的运移通道和储集空间,向斜构造部位挤压型顺层滑脱变形域所形成的顺层破碎带和网状裂缝系统成为页岩气向临近背斜构造部位运移或向地表散失的重要通道。

关键词: 顺层滑脱变形域, 形成机理, 地质意义, 下古生界, 页岩, 重庆

Abstract: The study presents the types,characteristics and the forming process of the bedding decollement deformation domain in the Lower Paleozoic shales in southeast Chongqing via mechanical analysis based on the observation of shale outcrops and cores,and discusses its geological significances in combination with shale gas exploration practices.Two types of bedding decollement deformation domains,namely compression-type and gravity-type,are recognized.The compression-type is formed when horizontal compressive tectonic stress dominates and shale layers are under the action of reverse fault;on the contrary,the gravity-type is formed when the overburden pressure dominates and the shale layers are under the action of normal fault.Compared with the gravity-type,the compression-type is more intense in stratum deformation with larger scale of influence on shales.Burial depth and dip angles are the key geological factors that control the formation of bedding decollement deformation domain in the same shale layer in a certain area.The critical dip angles for the compression-type expand gradually with the shale burial depth increasing,whereas that for the gravity-type decreases gradually with the increasing burial depth.The gravity-type is destructive to the preservation of shale gas.The bedding crushed zones and net fracture systems resulted by compression-type in an anticline are interpreted as the main migration pathways and reservoir space for shale gas,while those in an syncline are the main pathways for shale gas migrating to adjacent anticlines or releasing in the atmosphere.

Key words: bedding decollement deformation domain, formation mechanism, geological significance, Lower Paleozoic, shale, Chongqing

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