川东南地区龙一段页岩天然裂缝基本特征及其对页岩气高产富集的影响研究
Study on the Basic Characteristics of Natural Fractures in the Long 1 Formation Shale in Southeastern Sichuan and Its Influence on the High Yield Shale Gas Enrichment

为了提升我国页岩气产量与开采效率，深入探讨影响页岩气富集与保存的因素尤为关键，其中天然裂缝的发育程度起着关键作用。本研究结合测井、地震解释、岩心分析、薄片及扫描电镜等多种技术手段，基于川东南地区龙马溪组龙一段的实验数据和现场资料，系统分析了该区域页岩的天然裂缝特征、主控因素及其分布规律。同时，探讨了裂缝发育对页岩气富集的影响及多尺度裂缝系统对储层压裂改造效果的作用。研究结果表明，区域内的天然裂缝主要分为沉积裂缝、构造裂缝和异常压力裂缝，其中构造裂缝占主导地位。构造变形强度决定裂缝的发育密度，变形强度越大、曲率越大、断层越近，裂缝发育越密集。大尺度断裂显著影响页岩气逸散，二级断层会导致产量下降，而适度规模的大尺度断裂有助于提升产量。中小尺度裂缝的发育程度和产状对页岩气的富集与保存具有重要影响，裂缝的有效性直接关系到页岩气的自封闭性和保存能力。研究为川东南地区页岩气高效开发提供了理论依据和技术支持。
Enhancing China’s shale gas production and extraction efficiency necessitates a thorough investigation of factors affecting shale gas enrichment and preservation, with the development of natural fractures playing a pivotal role. This study employs well logging, seismic interpretation, core analysis, thin sections, and scanning electron microscopy data from the Long 1 Member of the Longmaxi Formation in southeastern Sichuan. It comprehensively analyzes the characteristics, controlling factors, and distribution patterns of natural fractures in the shale. Additionally, the research examines the impact of fracture development on shale gas enrichment and the effectiveness of multi-scale fracture systems in reservoir hydraulic fracturing. The findings indicate that natural fractures in the region are categorized into depositional fractures, tectonic fractures, and overpressure fractures, with tectonic fractures being predominant. The intensity of tectonic deformation critically influences fracture density; stronger deformation, greater curvature, and proximity to faults result in higher fracture density. Large-scale faults significantly affect shale gas leakage, particularly secondary faults, which can decrease gas production. Conversely, moderately sized large-scale faults may enhance production. The influence of medium and small-scale fractures is more complex, as their development and orientations are crucial for shale gas enrichment and preservation. The effectiveness of these fractures directly impacts the self-sealing and preservation capabilities of shale gas. This study provides essential theoretical and technical insights for the efficient development and resource evaluation of shale gas in southeastern Sichuan.