Measurement of fluid flow in boreholes by radioactivity

Claim 1

AN APPARATUS FOR MEASURING THE FLOW RATE OF A FLOWING FLUID WITHIN A WELL BORE WHICH COMPRISES A TRACER INJECTING DEVICE FOR PERIODICALLY INJECTING SMALL PREDETERMINED CONSTANT AMOUNTS OF A TRACER FLUID, SAID TRACER INJECTING DEVICE COMPRISING A LIQUID INTAKE CHAMBER AND A LIQUID DISCHARGE CHAMBER, A FLEXIBLE STRETCHABLE PARTITION SEPARATING SAID INTAKE CHAMBER AND SAID DISCHARGE CHAMBER, A FLUID ACTUATED INLET CHECK VALVE FITTED TO SAID INTAKE CHAMBER AND COMMUNICATING WITH THE FLUID SURROUNDING SAID TRACER INJECTING DEVICE, A FLUID ACTUATED OUTLET CHECK VALVE FITTED TO SAID DISCHARGE CHAMBER AND COMMUNICATING WITH THE FLUID SURROUNDING SAID TRACER INJECTING DEVICE, A RECIPROCATING PISTON EXTENDING INTO SAID INTAKE CHAMBER AND ADPTED TO PERIODICALLY CHANGE THE DISPLACEMENT OF SAID INTAKE CHAMBER A CONSTANT AMOUNT THEREBY CAUSING THE PERIODIC DISCHARGE OF A SMALL CONSTANT QUANTITY OF SAID TRACER FLUID THROUGH SAID OUTLET CHECK VALVE ON THE EXTENSION STROKE OF SAID PISTON, AND THE INTAKE OF A SIMILAR VOLUME OF SAID WELL BORE FLUID THROUGH SAID INLET CHECK VALVE ON THE RETRACTION STROKE OF SAID PISTON, A RADIATION DETECTOR A KNOWN FOR SUSPENDING SAID RADIATION DETECTOR A KNOWN DISTANCE DOWNSTREAMWARDLY FROM SAID OUTLET CHECK VALVE AND TIMING MEANS FOR CONTINUOUSLY MEASURING THE TIME INTERVAL BETWEEN SAID DISCHARGING OF SAID TRACER AND THE DETECTION OF SAID TRACER BY SAID RADIATION DETECTOR.