Borehole investigating apparatus of the induction logging type having a slotted metal support member with coil means mounted thereon

Claim 1

INDUCTION LOGGING APPARATUS FOR MOVEMENT THROUGH A BOREHOLE DRILLED INTO THE EARTH FOR INVESTIGATING SUBSURFACE EARTH FORMATIONS TRAVERSED BY SUCH BOREHOLE COMPRISING: A SUPPORTING HEAD ADAPTED FOR MOVEMENT THROUGH THE BOREHOLE; AN ELONGATED METAL SUPPORT MEMBER HAVING ONE END SECURED TO THE SUPPORTING HEAD AND HAVING A LONGITUDINALLY-EXTENDING SLOT CUT INTO THE BODY THEREOF; AT LEAST ONE COIL SECURED TO THE SUPPORT MEMBER OVER THE SLOTTED REGION THEREOF, THIS COIL COMPRISING IN PLURALITY OF NEARLY COMPLETE CIRCULAR TURNS POSITIONED IN PARALLEL PLANES WITH THE ENDS OF ADJACENT TURNS INTERCONNECTED BY LINEAR CONDUCTOR SEGMENTS WITH THE MIDPOINTS OF THE LINEAR CONDUCTOR SEGEMENTS LYING IN THE PLANE OF THE SLOT; AN ELONGATED SLEEVE MEMBER ENCLOSING THE SUPPORT MEMBER AND COIL AND HAVING ONE END ENGAGING THE SUPPORTING HEAD; AND SECURING MEANS ENGAGING THE OTHER END OF THE SLEEVE MEMBER AND SECURED TO THE SUPPORT MEMBER.