Experimental Study of Overburden and Stress Influence on Non-Darcy Gas Flow in Dakota Sandstone

Abstract

Abstract A series of laboratory experiments were conducted to investigate the influence of overburden and in-situ stresses on non-Darcy gas flow behavior in Dakota sandstone. Nitrogen was flooded through cylindrical core in a triaxial core holder under specific condition of temperature at 100°F, with core outlet pore pressure at 500 psi, axial and radial stress from 2.000 to 10,000 psi, and. nitrogen reservoir pump pressure at 2.000 psi with pump flow rates from 25 to 10,000 cc/hr at 80°F. Permeability and non-Darcy coefficient were determined using Forchheimer's method. It was found that with the increase of overburden and in-situ stresses, permeability decreases while non-Darcy flow coefficient increases. Average effective normal stress and shear stress were used to quantitatively express the influence of overburden and in-situ stresses. It was found that average effective normal stress has a good linear relationship with both permeability and non-Darcy flow coefficient. In contrast, average shear stress did not appear to influence the permeability and non-Darcy coefficient.