石油学报 ›› 2018, Vol. 39 ›› Issue (4): 402-415.DOI: 10.7623/syxb201804004

• 地质勘探 • 上一篇    下一篇

焦石坝背斜西缘龙马溪组页岩复合脉体中流体包裹体的古温度及古压力特征

李文1, 何生1, 张柏桥2, 何治亮3, 陈曼霏1, 张殿伟3, 李天义3, 高键3   

  1. 1. 中国地质大学构造与油气资源教育部重点实验室 湖北武汉 430074;
    2. 中国石油化工股份有限公司江汉油田分 公司 湖北潜江 433124;
    3. 中国石油化工股份有限公司石油勘探开发研究院 北京 100083
  • 收稿日期:2017-07-19 修回日期:2018-02-13 出版日期:2018-04-25 发布日期:2018-05-03
  • 通讯作者: 何生,男,1956年1月生,1982年获武汉地质学院学士学位,2002年获Curtin University of Technology博士学位,现为中国地质大学(武汉)教授、博士生导师,主要从事油气地质教学和科研工作。Email:shenghe@cug.edu.cn
  • 作者简介:李文,男,1991年2月生,2015年获中国地质大学(武汉)资源勘查工程(油气方向)专业学士学位,现为中国地质大学(武汉)硕士研究生,主要从事页岩气地质研究。Email:1101895551@qq.com
  • 基金资助:

    国家自然科学基金项目(No.41672139,No.41690134)、国家科技重大专项(2016ZX05034-002-003,2017ZX05005-001-008)、中央高校基本科研业务费专项资金项目(CUGQYZX1707)、高等学校学科创新引智计划项目(B14031)和国家基础地质调查项目(12120114046901,DD20160185)资助。

Characteristics of paleo-temperature and paleo-pressure of fluid inclusions in shale composite veins of Longmaxi Formation at the western margin of Jiaoshiba anticline

Li Wen1, He Sheng1, Zhang Baiqiao2, He Zhiliang3, Chen Manfei1, Zhang Dianwei3, Li Tianyi3, Gao Jian3   

  1. 1. Key Laboratory of Tectonics and Petroleum Resources of the Ministry of Education, China University of Geosciences, Hubei Wuhan 430074, China;
    2. Sinopec Jianghan Oilfield Company, Hubei Qianjiang 433124, China;
    3. Sinopec Petroleum Exploration and Production Research Institute, Beijing 100083, China
  • Received:2017-07-19 Revised:2018-02-13 Online:2018-04-25 Published:2018-05-03

摘要:

焦石坝背斜西缘JY-A井龙马溪组中段底部黑色页岩中发育张性顺层裂缝复合脉体,镜下观察发现复合脉体由石英脉、方解石脉和石英-方解石混杂脉复合组成。脉体样品中发育气-液两相盐水包裹体和高密度甲烷包裹体,均被捕获于同期CH4-NaCl-H2O不混溶流体体系。利用复合脉体中发育的流体包裹体对龙马溪组中段底部页岩层的古温度及古压力特征开展研究,显微测温发现石英脉中气-液两相盐水包裹体均一温度主要分布在230~268℃,盐度主要分布在4.02%~6.74%、平均为5.47%;方解石脉中气-液两相盐水包裹体均一温度主要分布在206~266℃,盐度主要分布在4.80%~5.26%、平均为5.07%。激光拉曼光谱分析发现石英脉中甲烷包裹体的甲烷拉曼散射峰分布在2 910.779 3~2 911.613 1 cm-1,计算的密度范围为0.245~0.302 g/cm3;显微测温发现甲烷包裹体的均一温度分布在-99.4~-87.0℃,计算的密度范围为0.249~0.304 g/cm3。依据与石英脉中甲烷包裹体共生的气-液两相盐水包裹体均一温度最低值和甲烷包裹体的密度范围计算甲烷包裹体古压力为99.297~160.281 MPa,古压力系数为1.43~2.31。对龙马溪组中段底部页岩复合脉体中记载古温度及古压力特征的气-液两相盐水包裹体和高密度甲烷包裹体的研究表明,在燕山期运动抬升前或初期侧向构造应力挤压造成页岩顺层裂缝,此时龙马溪组页岩层系接近最大古埋深、富含高演化热裂解干气,页岩气层处于中等—强超压状态。

关键词: 焦石坝背斜西缘, 龙马溪组, 复合脉体, 流体包裹体, 古温度, 古压力, 超压

Abstract:

The composite veins of tensional bedding fracture are developed in black shale at the bottom of the central member in Longmaxi Formation, Well JY-A, the western margin of Jiaoshiba anticline. Under the microscope, it can be observed that composite veins consist of quartz veins, calcite veins and quartz-calcite mixed veins. The gas-liquid brine inclusions and high-density methane inclusions are developed in vein samples, both of which are trapped in the same period of CH4-NaCl-H2O immiscible fluid system. In this paper, fluid inclusions developed in the composite veins are used for the research on the paleo-temperature and paleo-pressure characteristics of shale at the bottom of the center member in Longmaxi Formation. Through microthermometry, it is found for quartz veins that the homogenization temperature values of gas-liquid brine inclusions are mainly concentrated in the range of 230℃-268℃, and the salinity is primarily in the range of 4.02% -6.74%, averaged at 5.47%. For calcite veins, the homogenization temperature values of gas-liquid brine inclusions are mainly concentrated in the range of 206℃-266℃, and the salinity is primarily in the range of 4.80% -5.26%, averaged at 5.07%. Based on Laser Raman spectroscopy, it is detected that the methane Raman scatter peak of methane inclusions in quartz veins varies between 2 910.779 3 cm-1 and 2 911.613 1 cm-1, and the corresponding density values range from 0.245 g/cm3to 0.302 g/cm3. Through microthermometry, it is found that the homogenization temperatures of methane inclusions vary between -99.4℃ and -87.0℃, and the corresponding density values range from 0.249 g/cm3to 0.304 g/cm3. Based on the minimum homogenization temperatures of gas-liquid brine inclusion paragenetic in methane inclusions of quartz veins and the density range of methane inclusions, the paleo-pressure of methane inclusion is calculated to be 99.297 MPa-160.281 MPa, with the paleo-pressure coefficient of 1.43-2.31. As indicated by the research on the gas-liquid brine inclusion and high-density methane inclusion with the records of paleo-temperature and paleo-pressure characteristics in composite veins at the bottom of the central member in Longmaxi Formation, the lateral tectonic stress initiated at the early stage of Yanshanian uplifting or before Yanshanian uplifting caused the formation of shale bedding fractures; approaching to the maximum paleo-burial depth, the Longmaxi Formation shale was rich in the high-evolution thermal cracking dry gas, and shale gas reservoir was in the medium-strong overpressure state.

Key words: western margin of Jiaoshiba anticline, Longmaxi Formation, composite vein, fluid inclusions, paleo-temperature, paleo-pressure, overpressure

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