Patent ID: 6493632
Filing Date: 2002-12-10
Classification: G01V

Abstract:
A method of determining a parameter of interest of a subsurface formation containing a sand and a shale surrounding a borehole, the method comprising:(a) conveying an electromagnetic logging tool into the borehole and using at least one transmitter and one receiver on the tool to obtain measurements indicative of a horizontal and vertical resistivity of the formation; (b) obtaining a value for a total porosity of said formation, a fractional volume of the shale in said formation, and a resistivity of the shale in the formation, (c) using a processor for processing said measurements for obtaining a vertical and horizontal resistivity of the formation; (d) using a tensor petrophysical model in a processor for obtaining from said vertical and horizontal resistivities, said obtained total porosity, said obtained fractional shale volume and said obtained shale resistivity, the parameter of interest wherein said tensor petrophysical model comprises a laminar isotropic shale and a laminar sand that is at least one of (i) a clean sand, and, (ii) a sand having dispersed shale therein.