Productivity logging apparatus

Claim 1

IN A GAS PRODUCING WELL HAVING A PRODUCING ZONE THEREIN WITH A LIMITED VERTICAL EXTENT, THE COMBINATION COMPRISING A VERTICALLY MOVABLE CONDUIT EXTENDING DOWN HOLE WITH THE OPEN END THEREOF LOCATED VERTICALLY BETWEEN THE EXTREMITIES OF SAID PRODUCING ZONE, A PIPE FIXEDLY ATTACHED TO THE EXTERIOR OF SAID CONDUIT FOR VERTICAL MOVEMENT THEREWITH AT ALL TIMES AND EXTENDING DOWN BESIDE THE CONDUIT, SAID PIPE HAVING AN OPEN END LOCATED ADJACENT TO BUT DISPLACED A RELATIVELY SHORT VERTICAL DISTANCE FROM SAID CONDUIT OPEN END, MEANS FOR SEALING SAID WELL AT THE TOP THEREOF AROUND SAID CONDUIT AND PIPE, MEANS FOR CONNECTING THE ANNULUS OF THE WELL AROUND SAID CONDUIT FOR PASSING ONE STREAM OF SAID GAS THERETHROUGH, ANOTHER STREAM OF SAID GAS FLOWING THROUGH SAID CONDUIT, MEANS CONNECTED TO ONE OF SAID CONDUIT AND SAID ANNULUS CONNECTING MEANS AND LOCATED AT THE SURFACE ADJACENT TO SAID WELL FOR DETECTING THE PRESENCE OF A TRACER MATERIAL THAT IS INTRODUCED DOWN HOLE THROUGH SAID PIPE, AND MEANS FOR REGULATING THE RELATIVE RATE OF FLOW OF SAID TWO STREAMS OF GAS IN ORDER THAT THE LOCATION OF THE INTERFACE BETWEEN SAID TWO STREAMS MAY BY SHIFTED UNTIL THE PRESENCE OF TRACER MATERIAL IS NO LONGER DETECTED.