Patent ID: 6466020
Filing Date: 2002-10-15
Classification: E21B,G01V

Abstract:
A method for surveying a borehole comprising the steps of:generating an electromagnetic field in the region of the borehole by means of electric current flowing through a loop wire having a known configuration and location connected to a power source of electric current; measuring first and second vector components of said electromagnetic field at respective first and second sensors located at a measuring point in said borehole, said vector components each being substantially perpendicular to the axis of the borehole; determining a radial away distance to said measuring point from a first known location; computing theoretical first and second electromagnetic field vector components only, for said generated electromagnetic field at multiple locations of said first and second sensors at said radial away distance; and determining the location of said sensors by finding the location where the values of said measured first and second electromagnetic field vector components equal the values of computed theoretical first and second electromagnetic field vector components.