Dual-conduit drill pipe for earth boring

Abstract

Abstract A DUAL-CONDUIT DRILL PIPE COMPRISING INDIVIDUAL "LENGTHS," OR "JOINTS," WHICH "LENGTHS" ARE PERMANENTLY ASSEMBLED COMPONENTS FORMING DUAL LONGITUDINAL PASSAGES, OR CONDUITS, AND WHICH "LENGTHS" ARE ADAPTED TO BE THREADEDLY CONNECTED, ONE TO ANOTHER, TO FORM A "STRING" OF DUAL-CONDUIT DRILLING PIPE. ONE OBJECT OF THE INVENTION IS TO SOLVE THE HIGH THERMAL STRESS PROBLEM DUE TO DIFFERENTIAL THERMAL EXPANSION EXPERIENCED IN DUAL-CONDUIT DRILLING OPERATIONS, WHEREIN THE FLUID IN ONE CONDUIT MAY BE AT A CONSIDERABLY HIGHER TEMPERATURE THAN THE FLUID IN THE OTHER CONDUIT. FOR SHALLOW DRILLING THIS IS HEREIN ACCOMPLISHED BY EXTRUDING A DUALCONDUIT SECTION OF A SOFT, LOW STRENGTH ALUMINUM ALLOY, WITH THE HIGH THERMAL CONDUCTIVITY OF THE ALUMINUM ALLOY PROVIDING A HEAT EXCHANGE FACTOR SUFFICIENT TO REDUCE THE DIFFERENTIAL TEMPERATURE AND HENCE THE THERMAL STRESS TO SAFE VALUES, INTERMEDIATE DEPTH DRILLING REQIRES HIGHER STRENGTH ALUMINUM ALLOYS, AND THESE CANNOT BE EXTRUDED IN SUCH A FULL SECTION, MULTIPLE-VOID, HOLLOW-SHAPE AND CONSEQUENTLY TWO EXTRUSIONS ARE MADE AND ASSEMBLED BY WELDING IN SUCH A MANNER AS TO PROVIDE FOR LIMITED, RELATIVE LONGITUDINAL MOVEMENT AND EXPANSION OF THE INNER TUBE. DEEP DRILLING REQUIRES A HIGH STRENGTH, HIGH HARDNESS ALUMINUM ALLOY AND SUCH AN ALLOY CAN BE EXTRUDED ONLY AS CYLINDERS, OR TUBES, AT THIS STAGE OF THE EXTRUSION ART. CONSEQUENTLY, FOR DEEP DRILLING THE OUTER TUBE HAS WELDED THERETO LONGITUFINAL, INWARDLY PROJECTING, FINS TO SPACE AND RETAIN THE INNER TUBE AND TO PROVIDE FOR RELATIVE LONGITUDINAL MOVEMENT AND EXPANSION. FOR EXTREME DEPTH DRILLING THE LATTER CONSTRUCTION CAN BE OF STEEL. THE LIGHTNESS OF ALUMINUM IS DESIRABLE IN A DRILL PIPE, IN ALL RESPECTS EXCEPT FOR IMPOSING WEIGHT ON THE DRILL BIT. TO SOLVE THIS SHORTCOMING, THERE IS A DISCLOSED, SPECIAL HEAVY, DUAL-CONDUIT DRILL PIPE OF STEEL, THAT IS IMMUNE TO BUCKLING WHEN CAUSED BY MINOR DIFFERENTIAL THERMAL EXPANSION, FOUND AT THE BOTTOM OF THE HOLE.

Inventors

• 👤 Homer I Henderson

Bibliographic Details