METHOD OF ORIENTING A SECOND BOREHOLE RELATIVE TO A FIRST BOREHOLE

摘要

A method for creating a second borehole in an earth formation at a selected orientation relative to a first borehole, wherein a position parameter represents a position of the first borehole. The method comprises: a) providing a borehole element that generates a magnetic field; b) measuring the magnetic field; c) installing the borehole element in the first borehole; d) measuring the magnetic field in the second borehole; e) providing a finite element model of the magnetic field; f) calculating the magnetic field in the second borehole using the finite element model, and determining a difference between the calculated magnetic field in the second borehole and the measured magnetic field in the second borehole; g) adjusting the position parameter so as to minimise said difference; and h) determining a selected direction dependent on the adjusted position parameter and further drilling the second borehole in the selected direction.