(333g) Experimental and Numerical Study of Apparent Permeability in the Utica Shale

Shale formations are sedimentary heterogeneous rocks composed of micropores (pores less than 2 nm diameter), mesopores (pores with 2–50 nm diameter), and macropores (pores greater than 50 nm diameter), storing a significant amount of gas and playing an important role in the energy supply. The matrix permeability controls the long-term gas production from shale; therefore, quantifying permeability is essential for predicting gas production. In this study, experimental analyses in tandem with a numerical analysis were conducted to characterize and evaluate the permeability of shale. To determine the permeability of the Utica shale sample, the pressure pulse technique was conducted under varying confining stress while the pore pressure is kept constant. The pore size distribution and the average pore diameter of the Utica shale sample were determined using nitrogen gas adsorption technique. It was found that increasing confining pressure while pore pressure is constant decreases the apparent permeability. The apparent permeability model based on the second-order slip boundary condition was developed considering the poromechanics effects on gas transport mechanisms. The measured pressure profiles perfectly matched with data obtained from numerical simulation, indicating the applicability of the developed model in prediction of permeability in shale gas reservoirs.