Modeling adsorption–desorption hysteresis in shales: Acyclic pore model

Existing conventional measurements face challenges in characterizing transport properties of a shale because they are designed originally for formations with relatively wide pores and high permeability. The integrated analysis of such measurements helps us better understand the connected pore system of a shale formation when they are sensitive to the pore topology and cover a wider range of pore size. Here, we analyze nitrogen adsorption–desorption and mercury intrusion measurements to characterize the pore space of a shale. We determine pore-body size distribution by interpreting adsorption–desorption experiments. We also calculate pore-throat size distribution from mercury intrusion. We adopt the acyclic pore model, which embraces limited pore connectivity, and account for the connected path of the pores at the core scale. Our study distinguishes the pore size relevant to the storage and the flow conductance for the shale.