Slip correction and transient treatment of pressure oscillation method for permeability measurement

The pressure oscillation method is a technique for measuring the permeability of evolving porous media. This study presents the analytical solution of the pressure oscillation process considering the slip boundary based on the capillary model and perturbation expansion. The correspondence between the Klinkenberg relation and the Knudsen number is clarified, which provides a theoretical basis for applying the Klinkenberg correction to the pressure oscillation method. The data treatment method using the transient term is proposed, along with its applicable range. Experiments of the pressure oscillation method and pulse decay method are carried out to validate the method. The results show that the transient solution is consistent with the periodic solution, and the unification of the quasi-steady-state and unsteady-state methods under pressure oscillation conditions is achieved. In terms of measurement duration, the pressure oscillation method reduces the measurement time by at least four times compared to the classical pulse decay method. Based on the solution of permeability and porosity, the parameter effects on the experimental data are analyzed, and the dimensionless phase diagram of the amplitude ratio is given to provide a reference for practical engineering applications.