A comprehensive investigation of the effects of Organic-Matter pores on shale properties: A multicomponent and multiscale modeling

Abstract

Organic-matter (OM) pores play a significant role in the pore systems of shale formations. Numerous studies have analyzed the characteristics of OM pores. However, fewer studies reported the effects of OM pores on shale properties. In this study, a comprehensive pore-scale investigation of the impacts of OM pores on various physical properties of shale samples based on multicomponent and multiscale shale models is presented. To this end, a novel technique for constructing three-dimensional (3D), multicomponent, and multiscale shale models was proposed. Multiple shale models with different fractions of OM pores were then generated using the proposed algorithm. Based on these shale models, the effects of OM pores on the geometric properties, topological properties, correlation functions, and transport properties of pore space were comprehensively evaluated within the physics-based and realistic models. The results show that the addition of more OM pores in a pore system increases its connectivity, decreases its tortuosity, and strengthens the correlation of the voxels in the pore structure. At the same time, it enhances the surface roughness of the pore space, the proportions of small pores, and the number of isolated pores. Besides, the generation of more OM pores into the pore space leads to the increase of the permeability and decrease of the formation factor of the shale models.