An experimental study on starting pressure gradient of fluids flow in low permeability sandstone porous media

This paper presents the laboratory methods to obtain the complete non-Darcy flow curves of different low permeability sandstone porous media. The study develops a new "capillary pressure equilibrium method" to measure the starting pressure gradient, combining well with the conventional "differential pressure-flow rate method". Meantime, the relationships between starting pressure gradient and fluid viscosity, displacement pressure or the air permeability of the sample cores, especially the characteristics of permeability change when flow rate is low, are described and discussed. According to the experiment results, this paper get some useful experience formulae as well as applied plots.