TABLE OF CONTENTS Permeability is a measure of the ease with which a fluid can flow through a porous medium;it is the inverse of resistance to flow. The permeability of a sample is, therefore, determined by measuring the rate at which a liquid will flow through a porous medium of specific dimensions with a given pressure gradient across the length of the porous medium. A permeability equal to one darcy is obtained when a liquid, having a viscosity of one centipoise, flows at a rate of one cubic centimeter per second through a sample with a cross-sectional area of one square centimeter under a pressure gradient of one atmosphere per centimeter:
Generally, permeability is expressed as millidarcies (mD) because the darcy is a fairly large unit and mD is more convenient to use. In SI units, the darcy is expressed as micrometers squared ( ?m 2):
The liquid permeability measurement is made by determining the time required for a fixed volume of liquid, at constant temperature, to pass through a core at a specific pressure gradient. The Ruska Liquid Permeameter has acoreholder, thermometer well, cutoff valve, a burette for liquid volume measurement, and a pressure regulator. The upstream pressure is indicated on a calibrated pressure gauge.
Core samples are cut to the specific size required by the coreholder. The cores are washed gently to remove cuttings and dried in an oven at 110 C. If an outcrop core is used, it should be...
