Method and apparatus for directional tubing perforation

Claim 1

A METHOD OF LOCATING IN A FIRST TUBING STRING DISPOSED IN A CEMENT-FILLED BORHOLE THE RELATIVE POSITION OF A SECOND TUBING STRING IN SAID BOREHOLE, SAID METHOD COMPRISING: AT A FIRST POINT IN SAID FIRST TUBING STRING LATERALLY SCANNING THE SUBSTANCES IN SAID BOREHOLE WITH A SUBSTANTIALLY MONOENERGETIC BEAM OF LOW ENERGY GAMMA RAYS SUBSTANTIALLY CAPABLE OF PENETRATING SAID FIRST TUBING STRING AND SUBSTANTIALLY INCAPABLE OF PENETRATING THE MOST LATERALLY REMOTE PORTION OF THE WALL OF SAID BOREHOLE, SIMULTANEOUSLY AND IN FIXED ANGULAR RELATIONSHIP THEREWITH LATERALLY SCANNING SAID SUBSTANCES WITH A SUBSTANTIALLY MONODIRECTIONAL GAMMA RAY DETECTOR AT A SECOND POINT AXIALLY SPACED IN SAID FIRST TUBING STRING A DISTANCE WHICH IS FUNCTIONALLY RELATED TO THE AVERAGE INITIAL ENERGY OF SAID GAMMA RAYS, AND DERIVING A RECORDABLE ELECTRIC SIGNAL COMPOSED OF PULSES FUNCTIONALLY RELATED TO DETECTED GAMMA RAYS.