中国地质2026，Vol.53Issue(2)：449-465,17.DOI:10.12029/gc20250716002
基于微观-宏观岩石力学特征的脆性评价及在水力压裂中的应用——以川南筇竹寺组页岩储层为例
Brittleness evaluation based on micro-macro rock mechanical and fractal dimension and its application in hydraulic fracturing:A case study of the Qiongzhusi Formation shale reservoir in the southern Sichuan Basin
摘要
Abstract
[Objective]The Qiongzhusi Formation in the southern Sichuan Basin is abundant in shale gas resources.Multiple horizontal wells have achieved high commercial gas flow rates,showing favorable prospects for exploration and development.The formation has become a key target for natural gas exploration and development in the Sichuan Basin.In the Leshan-Jingyan region,the Qiongzhusi Formation is characterized by intensified tectonic deformation in the west and weakened deformation in the east,accompanied by large variations in burial depth and strong reservoir brittleness heterogeneity.These factors result in significant discrepancies in fracturing performance among different horizontal wells.Therefore,it is critical to accurately characterize the rock mechanical properties and brittleness of the formation across micro-to macro-scales.[Methods]This study focuses on the shale of the Qiongzhusi Formation in the Jingyan area.Nanoindentation tests and scanning electron microscopy were conducted to quantitatively analyze the influence of mineral grain types on microscopic rock mechanical characteristics.Triaxial compression experiments were performed to investigate the influence of lithology on macroscopic rock mechanical properties.A brittleness evaluation method based on mineral composition and microscopic brittleness characteristics was developed,and the fractal dimension was introduced to assess the complexity of sample fracture patterns,thereby evaluating the applicability of different brittleness evaluation methods in the study area.Logging interpretation methods of rock mechanics and brittleness were established based on lithology to evaluate the distribution characteristics of brittleness in the study area,and their impact on hydraulic fracture networks was analyzed.[Results](1)Quartz exhibits the highest elastic modulus and brittleness index,whereas clay minerals show the lowest.(2)Silty shale has an elastic modulus approximately 2 GPa higher than that of black shale,a Poisson's ratio lower by 0.02,and a compressive strength 30 MPa greater.(3)Three brittleness indices are most suitable for evaluating brittleness in the study area:BI1w developed in this study based on mineral composition and microscopic brittleness characteristics,BI5 calculated from macroscopic rock mechanical parameters,and BI10 calculated based on the energy evolution process.[Conclusions]The rock mechanical properties and brittleness of the study area are primarily controlled by burial depth,with localized abrupt changes influenced by lithology.A strong positive correlation exists between the brittleness index and the volume of the hydraulic fracture network,indicating that rock brittleness plays a controlling role in fracturing effectiveness.关键词
川南地区/筇竹寺组/页岩储层/岩石力学/脆性评价/脆性指数/地质调查工程Key words
Southern Sichuan Basin/Qiongzhusi Formation/shale reservoir/rock mechanics/brittleness evaluation/brittleness index/geological survey engineering分类
能源科技引用本文复制引用
杜奕霏,宿航,李瑞雪,邢梓萌,杨鸿,熊亮,邓虎成,马顺婷,何建华,李可赛..基于微观-宏观岩石力学特征的脆性评价及在水力压裂中的应用——以川南筇竹寺组页岩储层为例[J].中国地质,2026,53(2):449-465,17.基金项目
国家自然科学基金项目(42402148、42404144)资助. Supported by National Natural Science Foundation of China(No.42404144,No.42402148). （42402148、42404144）
