Measurement of stand-off of a decentralized nuclear well logging instrument

Claim 1

A WELL LOGGING TOOL COMPRISING AN ELONGATED HOLLOW BODY, MEANS SECURED TO SAID BODY FOR URGING A PREDETERMINED PART OF SAID BODY TOWARD A WELL DEFINING SURFACE, MEANS DISPOSED IN SAID BODY FOR EFFECTING NUCLEAR MEASUREMENTS OF THE SUBSURFACE STRATA ADJACENT SAID PREDETERMINED PART OF SAID BODY, AND MEANS FOR MEASURING THE THICKNESS OF THE MUD CAKE FORMED ALONG SAID SURFACE ADJACENT SAID PREDETERMINED PART OF SAID BODY, SAID LAST NAMED MEANS COMPRISING A PAIR OF SHOES MOUNTED ON SAID BODY FOR MOVEMENT RELATIVE THERETO, MEANS FOR URGING EACH OF SAID SHOES AWAY FROM SAID BODY IN SUBSTANTIALLY THE SAME DIRECTION AS SAID PREDETERMINED PART IS URGED, ONE OF SAID SHOES BEING SHARP SO AS TO PEIRCE ANY MUD CAKE AND THE OTHER OF SAID SHOES BEING BLUNT SO AS TO RIDE ON SAID MUD CAKE AND BOTH OF SAID SHOES BEING SHORT RELATIVE TO SAID BODY SO AS TO FOLLOW CONTOURS BRIDGED BY SAID BODY, AND MEANS FOR MEASURING THE RELATIVE DISPLACEMENT OF SAID SHOES.