METHOD OF CREATING A BOREHOLE IN AN EARTH FORMATION

摘要

A method of creating a borehole in an earth formation is provided, in a selected direction relative to an adjacent borehole formed in the earth formation. The method comprises arranging electromagnetic source means in a first of said boreholes at a plurality of locations along the length thereof, said electromagnetic source means inducing an electromagnetic field extending into a second of said boreholes. Electromagnetic field measuring means are arranged at a selected depth di in the second borehole, said measuring means being capable of measuring said electromagnetic field. The measuring means are operated so as to measure said electromagnetic field, and from the measured electromagnetic field, components of the electromagnetic field are determined including at least two components in directions substantially normal to the longitudinal axis of the first borehole. From said at least two components, a direction parameter indicative of the direction of the borehole relative to the adjacent borehole is determined.