天然气工业2025，Vol.45Issue(5)：124-135,12.DOI:10.3787/j.issn.1000-0976.2025.05.011
基于纳米压痕实验的藻白云岩力学参数跨尺度评价方法
Cross-scale evaluation method for mechanical properties of algal dolomite based on nanoindentation experiments
摘要
Abstract
Under the action of complex sedimentation,diagenesis and tectonism,different scales of pores,vugs and fractures are developed inside carbonate reservoirs,and strong heterogeneity is often exhibited,which makes it difficult to apply conventional mechanical experiments to comprehensively evaluate the influence of the internal structures on the rock mechanical parameters.Taking the algal dolomite of the 4th Member of Sinian Dengying Formation(Deng 4 Member)in the Sichuan Basin as an example,this paper systematically investigates the microstructural characteristics and mechanical properties of pores,algae clots and dolostone by virtue of micro-CT scanning and nanoindentation experiment.Then,a cross-scale evaluation method for rock mechanical properties of algal dolomite is proposed according to the homogenization theory,and the differences in the mechanical performance between dolostone and algae clot and their influences on macroscopic mechanical parameters are revealed.The following results are obtained.First,dolostone exhibits higher microscale strength,smaller plastic deformation,and greater resistance to fracture propagation,while algae clot is more disperse in microscopic mechanical parameters.Second,dolostone and algae clot present a good linear correlation in microscopic elastic modulus,hardness and fracture toughness.The macroscopic elastic modulus and Poisson's ratio of algal dolomite predicted by means of homogenization method are 1.90 and 1.39 times the uniaxial experimental values,respectively.Third,with the increasing pore development degree,the elastic modulus of algal dolomite decreases gradually,and its prediction range gets narrow gradually,whereas Poisson's ratio exhibits the opposite trend.Additionally,pore aspect ratio and microfissures further control macroscopic mechanical properties.The homogenization predictions align well with experimental results when the aspect ratio ranges from 0.087 to 0.202,or the fracture linear density falls between 0.30 and 0.63 fractures per meter.In conclusion,this method not only addresses the high core acquisition cost and poor experimental reproducibility,but also effectively reduces the overestimate caused by traditional homogenization method.It provides a new idea for the fine characterization of mechanical parameters of complex carbonate reservoirs,as well as a theoretical foundation for mechanical modeling and parameter prediction of complex reservoirs.关键词
纳米压痕/微米CT扫描/藻白云岩/多尺度力学性质/岩石力学/灯四段/均匀化方法Key words
Nanoindentation/Micro-CT scanning/Algal dolomite/Multi-scale mechanical properties/Rock mechanics/Deng 4 Member/Homogenization method分类
能源科技引用本文复制引用
李皋,上官自然,杨旭,李红涛,冯佳歆,李明昊,李泽..基于纳米压痕实验的藻白云岩力学参数跨尺度评价方法[J].天然气工业,2025,45(5):124-135,12.基金项目
国家自然科学基金项目"井下碳酸盐岩裂缝多物理场耦合变形与渗流机理研究"(编号:51674217)、四川省自然科学基金项目"超深层裂缝性气层钻井复杂工况井筒瞬态流动特性及井口回压控制压力反馈规律研究"(编号:2023NSFSC0929). （编号:51674217）
