地学前缘 ›› 2024, Vol. 31 ›› Issue (5): 1-16.DOI: 10.13745/j.esf.sf.2024.6.11

• 页岩储层裂缝研究 • 上一篇    下一篇

页岩储层构造裂缝活动期次及开启性研究进展与展望

丁文龙1,2,3(), 王垚1,2,3,*(), 张子游1,2,3, 刘天顺1,2,3, 程晓云1,2,3, 勾通1,2,3, 王生晖1,2,3, 刘霆锋1,2,3   

  1. 1.中国地质大学(北京) 能源学院, 北京 100083
    2.中国地质大学(北京) 海相储层演化与油气富集机理教育部重点实验室, 北京 100083
    3.中国地质大学(北京) 自然资源部页岩气资源战略评价重点实验室, 北京 100083
  • 收稿日期:2023-11-15 修回日期:2024-06-11 出版日期:2024-09-25 发布日期:2024-10-11
  • 通信作者: * 王垚(1994—),男,博士研究生,从事石油构造分析、非常规油气储层裂缝形成机制与定量表征及工程甜点评价预测工作。E-mail: yaowang@cug.edu.cn
  • 作者简介:丁文龙(1965—),男,教授,博士生导师,石油地质学专业,长期从事石油构造分析与控油气作用、非常规油气储层地应力分析及裂缝形成机制与定量表征及地质工程一体化研究方面的教学与科研工作。E-mail: dingwenlong2006@126.com
  • 基金资助:
    国家自然科学基金面上项目(42072173);国家自然科学基金面上项目(42372171)

Tectonic fracturing and fracture initiation in shale reservoirs—research progress and outlooks

DING Wenlong1,2,3(), WANG Yao1,2,3,*(), ZHANG Ziyou1,2,3, LIU Tianshun1,2,3, CHENG Xiaoyun1,2,3, GOU Tong1,2,3, WANG Shenghui1,2,3, LIU Tingfeng1,2,3   

  1. 1. School of Energy Resources, China University of Geosciences (Beijing), Beijing 100083, China
    2. Key Laboratory for Marine Reservoir Evolution and Hydrocarbon Abundance Mechanism, Ministry of Education, China University of Geosciences (Beijing), Beijing 100083, China
    3. Key Laboratory of Strategy Evaluation for Shale Gas, Ministry of Natural Resources of the People’s Republic of China, China University of Geosciences (Beijing), Beijing 100083, China
  • Received:2023-11-15 Revised:2024-06-11 Online:2024-09-25 Published:2024-10-11

摘要:

随着我国在非常规油气领域的研究不断深入和技术手段不断提高,页岩油气勘探开发工作取得了显著进展。大量生产实践结果表明:页岩储层裂缝是影响油气富集、高产和稳产的关键因素,页岩储层中裂缝的存在不仅可以改善储层的物性,还有利于后期的压裂改造。特别是储层中发育的构造裂缝,其活动期次与开启性的研究对于揭示页岩油气富集规律、保存条件等具有重要意义。早期对于页岩储层裂缝的研究集中在裂缝分类、识别与表征、裂缝发育主控因素分析与分布预测及建模等方面,而对于裂缝的形成时间与活动期次厘定、裂缝开启性的主控因素、裂缝开启与闭合机理、裂缝开启程度定量表征研究相对薄弱,制约了我国盆内页岩油气的高效勘探开发。为此本文在充分调研了国内外页岩储层构造裂缝研究成果的基础上,围绕页岩储层构造裂缝活动期次及开启性这一主题,重点梳理了页岩裂缝期次划分、充填脉体定年、开启性主控因素分析及开启程度定量表征方面的研究进展。裂缝活动期次的划分方法可分为两类:地质定性分析和裂缝充填物地球化学示踪分析。在实际应用中,上述方法只能得到裂缝活动期次相对的先后顺序,且会受到埋藏史、热史等基础地质资料精度的影响,其应用存在一定局限性。裂缝中脉体多为碳酸盐岩矿物和石英,高精度微区原位U-Pb定年技术的出现,使得厘定不同组系裂缝脉体形成的绝对年龄成为可能,避免了由于热史、埋藏史认识差异带来的流体活动时间的多解问题。影响构造裂缝开启性的主控因素较多,不仅受到岩石本身特性的影响,还受到现今地应力、地层流体压力等因素的控制。裂缝中广泛分布的纤维状充填物岩石学特征记录了晶体的生长过程,此类特殊的晶体形态是裂缝曾经存在多期活动的证据,揭示了裂缝多次开启-闭合的演化过程。目前主要应用开度这一参数来表征裂缝的开启程度,或是通过计算及实验获取裂缝开启压力间接表征其开启性。在总结并分析上述研究成果后指出了页岩储层构造裂缝活动期次及开启性研究中存在的关键问题及发展趋势,旨在丰富和完善页岩油气储层研究的理论和方法体系,为我国页岩油气的构造保存条件和富集机理研究提供重要的科学依据。

关键词: 页岩储层, 构造裂缝, 活动期次, 裂缝开启性, 裂缝脉体, 定量表征

Abstract:

Shale oil and gas development has gained significant progress in China with the contineous research and technological advancements in unconventional oil and gas. Extensive production practices demonstrate that natural fracture development in shale reservoirs is a crucial factor influencing oil and gas enrichment, high production and stable yield, for fractures not only improve reservoir properties but also facilitate subsequent reservoir modification during hydrollic fracturing. The formation stages of tectonic fractures and fracture initiation holds significant importance for revealing the oil and gas enrichment patterns and preservation condition. Early studies on shale reservoir fractures mainly focused on fracture classification/identification/characterization, main controlling factors of fracture development, and fracture distribution prediction and modelling, with less attention to the determination of fracture formation stages, main controlling factors of fracture initiation, mechanism of fracture opening and closing, and quantitative characterization of fracture openness—this restricts the efficient exploration and development of shale oil and gas in China. This paper highlights research progress addressing the above gaps, particularly the delineation of fracturing stages, dating of filling veins, and quantification of fracture openness based on comprehensive literature review. The classification methods for fracturing stages can be divided into two categories: qualitative geological analysis and geochemical tracing of fracture fillings. These methods however have practical limitations, where only the relative sequence of fracturing stages can be obtained, and the results are affected by the accuracy of basic geological data such as burial/thermal histories. Most of the fissure veins in fractures are carbonate minerals and quartz. With the advent of high precision in situ U-Pb microprobe dating technology, it is possible to determine the absolute ages of different veins while avoiding the problem of multiple solutions to fluid activity periods due to differences in interpreting thermal/burial histories. The initiation of tectonic fractures is controlled by many factors, not only by rocks’ intrinsic properties but also the current crustal stress and formation-fluid pressure. The petrological characteristics of fibrous fillings widely distributed in fractures record the crystal growth process. Such special crystal morphology provides the evidence of multi-stage tectonic fracturing, revealing a fracture evolutionary process with multiple fracture opening and closing. At present, fracture openness is characterized using the fracture apature parameter or inferred by the fracture initiation pressure obtained by calculation and experiment. Based on the analysis of the above results, this paper points out the key problems and development trends in the study of the fracturing stages and initiation of tectonic fractures in shale reservoirs, aiming to enrich and improve the theory and research methodology for shale oil and gas reservoirs, and provide an important scientific basis for the study of structural preservation conditions and enrichment mechanism of shale oil and gas in China.

Key words: shale reservoir, tectonic fracture, activity period, fracture openness, fracture vein, quantitative characterization

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