Experimental Investigations to Study the impact of Pore Fluid Chemistry on Tight Sands Permeability

Abstract

In this study tight sands samples from Kirthar fold belt area were obtained to investigate the impact of pore fluid composition on petro physical properties. The assumptions that the gas permeability is equivalent to liquid permeability could lead to an overestimation of aquifer encroachment if gas permeability values obtained during routine core analysis are given to the aquifer. Hence, such analysis necessitates making measurements using formation compatible brines (NaCl) and is essential to understand tight gas reservoirs productivity. This study conducted single phase gas and liquid flow properties of tight sandstone samples by conducting series of experiments. The intrinsic slip free gas permeability measured was ranged between 0.0012 m Darcy and 25mDarcy. The intrinsic gas permeability (slip corrected) was higher by factor of 1.25 to 20 than the permeability measured with water. Moreover, the permeability results showed that the changing brine (NaCl) composition has large sensitivity to those samples which were exhibiting very low absolute permeability less than 0.1mDarcy.