Abstract: Fractures are developed to varying degrees in the hydrocarbon reservoirs characterized with deep strata, deep water environment, unconventional resources, and remaining oil in mature oilfield. These fractures can connect matrix pores, thus enhancing reservoir permeability and improving well productivity. Therefore, a systematic summary of methods for fracture logging identification and evaluation is of vital theoretical and practical significances. Based on a review of domestic and international literatures combined with our work experiences, this paper investigates the primary controlling factors of fracture development, and summarizes the main geological and geophysical methods for fracture identification and detection. The research results show as follows.(1)Tectonic stress field, structural style, and lithological association are identified as key factors for fracture development. (2)Fracture develop zones are characterized by variations in bore hole diameter, an increase ininterval transit time, a reduction inbulk density, and a reduction in significant resistivity. (3)On the array acoustic variable density logging image, the fracture development zones exhibit V-shape interference patterns, while formation imaging logs enable the direct extraction of fracture geometry and calculation of fracture parameters. (4)Construction of fracture characterization parameters through integration of multiple logging methods can enable semi-quantitative discrimination of fracture development zones, and artificial intelligence integration can enhance identification efficiency. (5)Fracture effectiveness evaluation mainly focuses on fracture openness and extendibility. Fractures that are aligned with the direction of the current maximum horizontal principal stress under stress relaxation conditions exhibit favorable openness. (6)Fracture extendibility can be assessed by integrating logging data obtained at various depths of investigation into formations, enabling the characterization of fractures in the bore hole wall, as well as near-well bore and far-field regions. These findings can provide theoretical guidance and technical support for fracture logging identification and its effectiveness evaluation, thereby increasing reserve and production in the abovesaid mature oilfield.

Key words: fracture, well logging evaluation, fracture effectiveness, imaging log, sonic log, artificial intelligence

摘要： “两深一非一老”(陆上深地、海域深水、非常规油气和老油田剩余油)储层均不同程度地发育裂缝,裂缝可以沟通基质孔隙,提升储层渗透率和油气井产能。系统归纳总结裂缝的测井识别与评价方法具有重要的理论与实践意义。基于国内外文献调研和自身工作实践,开展裂缝发育主控因素调研,梳理了裂缝识别与探测的主要地质与地球物理方法。研究结果表明:①构造应力场、构造样式和岩性组合等是裂缝发育的主控因素;②裂缝发育带导致井径发生变化、声波时差增大、密度降低以及电阻率显著降低;③裂缝发育带在阵列声波测井变密度图像上将呈现“V”字形干涉条纹,成像测井可直观地拾取裂缝面的形态和计算裂缝孔隙度等参数;④不同测井方法的融合,通过构建裂缝表征参数可实现裂缝发育带的半定量判别,人工智能融入可提升识别与探测裂缝的效率;⑤裂缝有效性评价主要侧重裂缝开启性和裂缝延伸性评价,与现今最大水平主应力方向平行且处于弱应力区的裂缝开启性较好;⑥裂缝延伸性可以依托不同探测深度测井资料,实现从井壁到井旁到远井的裂缝发育特征的判别。研究成果可为裂缝的测井识别与有效性评价提供理论指导与技术支持,助力“两深一非一老”油气增储上产。

关键词: 裂缝, 测井评价, 裂缝有效性, 成像测井, 声波测井, 人工智能