Patent ID: 7448262
Filing Date: 2008-11-11
Classification: E21B,G01N

Abstract:
1. A method of estimating a permeability of an earth formation, the formation containing a formation fluid, the method comprising: (a) withdrawing fluid from the earth formation using a probe having a substantially circular aperture in hydraulic communication with the formation; (b) stopping the withdrawal of the fluid at a defined time; (c) making transient pressure measurements before and after the defined time; with a probe in a borehole in the earth formation, the probe having an aperture that is substantially non-elliptical; (d) obtaining a first estimate of permeability by analyzing a subset of the pressure measurements made only after the defined time and a second estimate of permeability from the pressure measurements made before and after the defined time; and (e) determining from the first and second estimates of permeability at least one of (A) a horizontal permeability of the formation, and (B) a vertical permeability of the formation.