Micromechanical properties of laminated shale based on dot matrix technology

Shale is a complex formation with multi-scale mechanical properties and a highly heterogeneous composition. In this paper, several indentation experiments were conducted on four rock samples from lacustrine laminated shale in the Bohai Bay Basin using the dot matrix technology. The purposes are to obtain the spatial distribution of their mechanical properties, identify the micromechanical properties, and confirm the strong heterogeneity of the sample in the microscale test window. Furthermore, through Gaussian mixture model deconvolution analysis, each sample was clustered into three independent clusters (i.e., physical phases) on the basis of the network indentation data, and the three physical phases and their corresponding percentages were obtained from the network indentation data through deconvolution. Finally, the Mori-Tanaka, Dilute, and Self-consistent methods were used to determine the homogenized elastic properties of the samples, and the nanoindentation data were upgraded to the macroscale. The results show that the equivalent elastic modulus and convolution values obtained by the Self-consistent method are the closest among the samples investigated. The Young's modulus obtained by the homogenization and deconvolution methods ranges from 17.73 to 33.55 GPa, which proves the applicability of the nanoindentation technique in the study of the geomechanics of laminated shale formations.