石油与天然气地质 ›› 2024, Vol. 45 ›› Issue (1): 1-14.doi: 10.11743/ogg20240101

• 油气地质 •    

深层-超深层致密储层天然裂缝分布特征及发育规律

曾联波1(), 巩磊2, 宿晓岑2, 毛哲1   

  1. 1.中国石油大学(北京) 油气资源与探测国家重点实验室,北京 102249
    2.东北石油大学 环渤海能源研究院,河北 秦皇岛 066004
  • 收稿日期:2023-08-17 修回日期:2023-12-10 出版日期:2024-02-01 发布日期:2024-02-29
  • 第一作者简介:曾联波(1967—),男,博士、教授,裂缝性储层与非常规油气储层形成、分布及预测技术研究。E-mail: lbzeng@cup.edu.cn
  • 基金项目:
    国家自然科学基金企业创新发展联合基金重点项目(U21B2062);黑龙江省优秀青年科学基金项目(YQ2022D006)

Natural fractures in deep to ultra-deep tight reservoirs: Distribution and development

Lianbo ZENG1(), Lei GONG2, Xiaocen SU2, Zhe MAO1   

  1. 1.State Key Laboratory of Petroleum Resources and Prospecting,China University of Petroleum (Beijing),Beijing 102249,China
    2.Bohai Rim Energy Research Institute,Northeast Petroleum University,Qinhuangdao,Hebei 066004,China
  • Received:2023-08-17 Revised:2023-12-10 Online:2024-02-01 Published:2024-02-29

摘要:

天然裂缝是深层-超深层致密储层的有效储集空间和主要渗流通道,影响着致密储层油气的运移、富集、单井产能、开发方式及开发效果。通过对近年来致密储层裂缝研究成果总结和文献综述,分析了深层-超深层致密储层天然裂缝分布特征及发育规律。将致密储层天然裂缝分为大尺度裂缝、中尺度裂缝、小尺度裂缝和微尺度裂缝4个级别。不同尺度裂缝分布具有幂律分布的特点,裂缝尺度越大,数量越少;裂缝尺度越小,数量越多。大、中尺度裂缝主要起渗流作用,小尺度裂缝主要起渗流和储集作用,而微尺度裂缝主要起储集作用。在地层埋藏过程中的应力体制演化决定了不同时期天然裂缝的类型、产状及其力学性质;构造应力大小、岩石力学层的力学性质和厚度差异控制了多尺度裂缝的形成分布及其发育程度。构造变形导致不同构造部位的局部应力和应变分布产生差异,增强了裂缝发育的非均质性。逆冲断层通过控制其上盘地层变形控制了“裂缝域”的分布规律;走滑断层的组合样式、活动方式和岩石力学层共同控制了相关裂缝的三维空间展布。裂缝形成演化过程中的开启-闭合规律决定了裂缝的储集空间,记录了裂缝有效性的演化历史。

关键词: 断裂带结构, 有效性演化, 天然裂缝, 多尺度裂缝, 致密储层, 深层-超深层

Abstract:

Natural fractures serve as effective storage spaces and primary seepage pathways in deep to ultra-deep tight reservoirs, affecting the hydrocarbon migration and enrichment, single-well productivity, and exploitation methods and outcomes of the reservoirs. Based on the summary of latest research results and literature review on fractures in tight reservoirs, this study delves into the distribution characteristics and developmental patterns of natural fractures in deep to ultra-deep tight reservoirs. The results show that the natural fractures are of large, meso, small, and micro scales, following a power law distribution. In other words, a larger scale corresponds to a smaller number of fractures, and vice versa. Large- and meso-scale fractures primarily facilitate seepage; small-scale ones mainly enable seepage and storage; and micro-scale ones principally serve as storage spaces. The type, occurrence, and mechanical properties of the natural fractures formed across different periods are determined by the evolution of stress regime during stratigraphic burial. The formation, distribution, and developmental degree of multi-scale fractures are subjected to the magnitude of tectonic stress, the mechanical properties of rock mechanical stratigraphy, and the thickness differences in mechanical layers. Structural deformation results in varied local stress and strain distribution at different structural locations, increasing fracture heterogeneity. Thrust faults control the distribution of faulted fracture zones by controlling the deformation of strata on the hanging walls. The combination style and movement mode of strike-slip faults, along with rock mechanical stratigraphy, jointly dictate the three-dimensional spatial distribution of related fractures. Furthermore, the crack-seal patterns of the fractures during formation and evolution determine their storage spaces and record the evolutionary history of their effectiveness.

Key words: fault zone structure, effectiveness evolution, natural fracture, multi-scale fracture, tight reservoir, deep to ultra-deep reservoir

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