石油学报 ›› 2018, Vol. 39 ›› Issue (4): 379-390.DOI: 10.7623/syxb201804002

• 地质勘探 • 上一篇    下一篇

川东南丁山构造龙马溪组页岩构造裂缝期次及演化模式

范存辉1,2, 李虎1,2,4, 钟城1,2, 秦启荣1,2, 胡东风3, 张羽1,2, 何顺1,2, 张玮4   

  1. 1. 西南石油大学地球科学与技术学院 四川成都 610500;
    2. 西南石油大学油气藏地质及开发工程国家重点实验室 四川成都 610500;
    3. 中国石油化工股份有限公司勘探分公司 四川成都 610041;
    4. 中国石油塔里木油田公司 新疆库尔勒 841100
  • 收稿日期:2017-07-26 修回日期:2018-03-01 出版日期:2018-04-25 发布日期:2018-05-03
  • 通讯作者: 范存辉,男,1980年12月生,2002年获西南石油学院学士学位,2015年获成都理工大学博士学位,现为西南石油大学地球科学与技术学院讲师,主要从事构造与油气方面的教学和研究工作。Email:fanchswpi@163.com
  • 作者简介:范存辉,男,1980年12月生,2002年获西南石油学院学士学位,2015年获成都理工大学博士学位,现为西南石油大学地球科学与技术学院讲师,主要从事构造与油气方面的教学和研究工作。Email:fanchswpi@163.com
  • 基金资助:

    国家科技重大专项(2017ZX05036-003-003)资助。

Tectonic fracture stages and evolution model of Longmaxi Formation shale, Dingshan structure,Southeast Sichuan

Fan Cunhui1,2, Li Hu1,2,4, Zhong Cheng1,2, Qin Qirong1,2, Hu Dongfeng3, Zhang Yu1,2, He Shun1,2, Zhang Wei4   

  1. 1. School of Science and Technology, Southwest Petroleum University, Sichuan Chengdu 610500, China;
    2. State Key Laboratory of Oil and Gas Reservoir Geology and Exploitation, Southwest Petroleum University, Sichuan Chengdu 610500, China;
    3. Sinopec Exploration Company, Sichuan Chengdu 610041, China;
    4. PetroChina Tarim Oilfield Company, Xinjiang Korla 841100, China
  • Received:2017-07-26 Revised:2018-03-01 Online:2018-04-25 Published:2018-05-03

摘要:

川东南丁山构造龙马溪组的页岩气蕴藏量巨大,裂缝对页岩气的富集及产能具有重要影响。综合利用野外露头、岩心、成像测井、包裹体分析、声发射实验以及(U-Th)/He年龄测定等,对该区构造裂缝形成期次及演化模式开展综合研究。研究表明:野外露头和岩心裂缝均主要以构造成因的剪切缝为主,以高角度、大切深、高充填为特征,据其交切关系及产状特征可划分为平面剪切缝和剖面剪切缝。龙马溪组构造裂缝可分为3期:第1期构造裂缝形成于燕山运动中—晚期(82.5~72.1 Ma),裂缝充填物主要为方解石,充填程度较高,均一温度为295.6~325.2℃,古地应力的最大有效主应力为97.06 MPa,主应力方向为135°±15°,裂缝方位主要为NWW—SEE、NNE—SSW向平面"X"型共轭剪切缝以及NE向剖面剪切缝;第2期构造裂缝形成于燕山运动末期—喜马拉雅运动中期(72.1~31.2 Ma),裂缝充填物为方解石,其次为硅质或铁质,均一温度为189.1~232.4℃,古地应力的最大有效主应力为90.71 MPa,主应力方向为45°±15°,裂缝方位主要为近SN向、NEE向平面剪切缝以及NW向剖面剪切缝;第3期构造裂缝形成于喜马拉雅运动晚期—现今(31.2~0 Ma),仅形成少量的NW向剖面剪切缝,裂缝充填程度低,充填物为少量方解石,古地应力的最大有效主应力为76.55 MPa。第1期和第2期为主要的成缝期,第3期主要对前期裂缝进行叠加和改造。结合地质力学理论,最终建立了3期裂缝发育的演化模式。

关键词: 龙马溪组页岩, 构造裂缝, 形成期次, 演化模式, 丁山构造

Abstract:

Huge shale gas reserves exist in Longmaxi Formation,Dingshan structure,Southeast Sichuan,where fractures have an important effect on shale gas enrichment and productivity. Based on field outcrop,core,image log,inclusion analysis,acoustic emission experiment and (U-Th)/He dating,the formation stages and evolution models of tectonic fractures in this area are comprehensively studied. The research shows that the high-angle plane shear fractures and low-angle profile shear fractures of tectonic origin are mainly developed in field outcrops with various types of core fractures,dominated by high-angle shear fractures of tectonic origin. The fracture occurrence of field outcrop is better consistent with the core and image logging interpretation. The tectonic fractures of Longmaxi Formation can be divided into three stages. In the first stage,tectonic fractures were formed in the late Yanshanian movement (82.5-72.1 MPa). The fillings of fractures are mainly calcite,followed by silicon or iron,showing a high filling degree. The homogenization temperature is 295.6-325.2℃,the maximum effective principal stress of paleo-geostress is 97.06 MPa,and the direction of principal stress is 135°±15°. The fracture orientation is mainly shown as the horizontal "X" conjugate shear fractures with NWW-SEE and NNE-SSW trending as well as the NE profile shear fractures. In the second stage,tectonic fractures were formed in the late Yanshanian movement and the middle Himalayan movement (72.1-31.2 Ma). The fracture fillings are calcite with low filling degree. The homogenization temperature is 189.1-232.4℃,the maximum effective principal stress of paleo-geostress is 90.71 MPa,the direction of principal stress is 45°±15°,and the fracture orientation is mainly shown as the plane "X" conjugate shear fractures with near-SN and NEE trending as well as NW-trending shear fractures on the profile. In the third stage,tectonic fractures were formed in the late Himalayan movement till now (31.2-0 Ma),and only a few NW-trending shear fractures have been formed on the profile. The fractures are basically unfilled. The maximum effective principal stress of paleo-geostress is 76.55 Mpa. The first and second stages are the main fracture formation stages,while the third stage is to transform the earlier fractures. Combined with the theory of geomechanics,the genetic model of fracture development in three phases was established in this study.

Key words: Longmaxi Formation shale, tectonic fractures, formation stage, evolution model, Dingshan structure

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