# US 5,330,016 A · Drill bit and other downhole tools having electro-negative surfaces and sacrificial anodes to reduce mud balling > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 5,330,016 A - Document ID: US5330016A - Status: Granted - Kind: A - Application number: 08/060,182 - Filed: 1993-05-07 - Granted: 1994-07-19 - Earliest claimed: 1993-05-07 - Assignees: Barold Technology, Inc. - Inventors: William C. Paske; Paul F. Rodney; Ronald D. Ormsby - Web page: https://patentgrep.com/patent/US5330016A ## CPC - E21B 17/1085: {Wear protectors; Blast joints; Hard facing} - E21B 10/00: Drill bits (specially adapted for deflecting the direction of boring {E21B7/064}; with means for collecting substances E21B27/00) - E21B 12/00: Accessories for drilling tools - E21B 17/00: Drilling rods or pipes; Flexible drill strings; Kellies; Drill collars; Sucker rods; {Cables;} Casings; Tubings - E21B 17/003: {with electrically conducting or insulating means (E21B17/028 and E21B17/023 take precedence)} - E21B 17/1078: {Stabilisers or centralisers for casing, tubing or drill pipes (E21B17/1007 - E21B17/1064 take precedence)} - E21B 41/00: Equipment or details not covered by groups E21B15/00 - E21B40/00 - E21B 41/0085: {Adaptations of electric power generating means for use in boreholes} - E21B: EARTH OR ROCK DRILLING; OBTAINING OIL, GAS, WATER, SOLUBLE OR MELTABLE MATERIALS OR A SLURRY OF MINERALS FROM WELLS ## Abstract Various steel, downhole tools and components of a drill string, including, as examples, a PDC drill bit, a rotary rock bit, a cross-over sub, a stabilizer, a reamer, a hole enlarger and a coring bit, are selectively treated to cause certain of their parts to be electro-negative with respect to steel, and certain other parts to either have the same electro-negativity as steel, or to be treated to be electro-positive with respect to steel. ## Claims ### Claim 1 A drill bit adapted to be connected to a drill string, comprising: a steel bit body having a first end defining a cutting face, said cutting face having a plurality of cutters mounted therein; said steel bit body having a second end defining a tubular body adapted to be threaded into a drill string; and said steel bit body having a portion thereof intermediate said first and second ends defining an exterior peripheral stabilizer surface, said drill bit being characterized by said cutting face being electro-negative with respect to the standard reduction potential of steel. ### Claim 2 (depends on 1) The drill bit according to claim 1, being characterized further by said cutting face having been subjected to a gas nitriding process to cause said cutting face to be electro-negative with respect to the standard reduction potential of steel. ### Claim 3 (depends on 1) The drill bit according to claim 1, being characterized further by said intermediate portion of said drill bit also being electro-negative with respect to the standard reduction potential of steel. ### Claim 4 (depends on 3) The drill bit according to claim 3, being characterized further by said intermediate portion having been subjected to a gas nitriding process to cause said intermediate portion to be electro-negative with respect to the standard reduction potential of steel. ### Claim 5 (depends on 1) The drill bit according to claim 1, being characterized further by at least a portion of said second end of said drill bit defining a tubular body being electro-positive with respect to the standard reduction potential of steel. ### Claim 6 (depends on 5) The drill bit according to claim 5, being characterized further by said at least a portion of said second end having been subjected to a galvanizing process to cause said at least a portion of said second end to be electro-positive with respect to the standard reduction potential of steel. ### Claim 7 (depends on 1) The drill bit according to claim 1, being characterized further by at least a portion of said second end of said drill bit defining a tubular body having the same degree of electro-negativity as the standard reduction potential of steel. ### Claim 8 (depends on 7) The drill bit according to claim 7, wherein said second end of said drill bit defining a tubular body comprises a shank and a threaded pin. ### Claim 9 A portion of a drill string for drilling an earth borehole, comprising in combination: a steel bit body having a first end defining a cutting face, said cutting face having a plurality of cutters mounted therein; said steel bit body having a second end defining a tubular body adapted to be threaded into a steel cross over sub, and a steel cross-over sub being adapted to threadedly mate with said second end of said drill bit, said combination being characterized by at least a portion of said steel bit body being electro-negative with respect to the standard reduction potential of steel. ### Claim 10 (depends on 9) The combination according to claim 9, being characterized further by said at least a portion of said steel bit body having been subjected to a gas nitriding process to cause said at least a portion of said steel bit body to be electro-negative with respect to the standard reduction potential of steel. ### Claim 11 (depends on 10) The combination of claim 10, being further characterized by at least a portion of said cross-over sub being electro-positive with respect to the standard reduction potential of steel. ### Claim 12 (depends on 11) The combination according to claim 11, being characterized further by said at least a portion of said cross-over sub being subjected to a galvanizing process to cause said at least a portion of said cross-over sub to be electro-positive with respect to the standard reduction potential of steel. ### Claim 13 (depends on 9) The combination of claim 9, being further characterized by at least a portion of said cross-over sub having the same degree of electro-negativity as the standard reduction potential of steel. ### Claim 14 A drill bit adapted to be connected to a drill string, comprising: a steel bit body having a first end having a plurality of rotatable cutting elements mounted thereto; said steel bit body having a second end defining a tubular body adapted to be threaded into a drill string; and said steel bit body having a portion thereof intermediate said first and second ends defining an exterior peripheral stabilizer surface, said drill bit being characterized by said first end of said bit body being electro-negative with respect to the standard reduction potential of steel. ### Claim 15 (depends on 14) The drill bit according to claim 14, being characterized further by said intermediate portion of said drill bit also being electro-negative with respect to the standard reduction potential of steel. ### Claim 16 (depends on 15) The drill bit according to claim 15, being characterized further by said first end and said intermediate portion having been subjected to a gas nitriding process to cause said first end and said intermediate portion to be electro-negative with respect to the standard reduction potential of steel. ### Claim 17 (depends on 14) The drill bit according to claim 14, being characterized further by at least a portion of said second end of said drill bit defining a tubular body being electro-positive with respect to the standard reduction potential of steel. ### Claim 18 (depends on 17) The drill bit according to claim 17, characterized further by said at least a portion of said second end having been subjected to a galvanizing process to cause said at least a portion of said second end to be electro-positive with respect to the standard reduction potential of steel. ### Claim 19 (depends on 14) The drill bit according to claim 14, being characterized further by at least a portion of said second end of said drill bit defining a tubular body having the same degree of electro-negativity as the standard reduction potential of steel. ### Claim 20 (depends on 14) The drill bit according to claim 14, wherein said second end of said drill bit defining a tubular body comprises a shank and a threaded pin. ### Claim 21 A portion of a drill string for drilling an earth borehole, comprising in combination: a steel bit body having a first end having a plurality of rotatable cutting elements mounted thereto; said steel bit body having a second end defining a tubular body adapted to be threaded into a steel cross over sub, and a steel cross-over sub being adapted to threadedly mate with said second end of said drill bit, said combination being characterized by at least a portion of said steel bit body being electro-negative with respect to the standard reduction potential of steel. ### Claim 22 (depends on 21) The combination according to claim 21, being characterized further by said at least a portion of said steel bit body having been subjected to a gas nitriding process to cause said at least a portion of said steel bit body to be electro-negative with respect to the standard reduction potential of steel. ### Claim 23 (depends on 22) The combination of claim 22, being further characterized by at least a portion of said cross-over sub being electro-positive with respect to the standard reduction potential of steel. ### Claim 24 (depends on 23) The combination according to claim 23, being characterized further by said at least a portion of said cross-over sub having been subjected to a galvanizing process to cause said at least a portion of said cross-over sub to be electro-positive with respect to the standard reduction potential of steel. ### Claim 25 A drill coring bit adapted to be connected to a drill string, comprising: a steel bit body having a first end defining a coring face, said coring face having a plurality of cutters mounted therein and a center orifice for receiving a core; said steel bit body having a second end defining a tubular body adapted to be threaded into a drill string; and said steel bit body having a portion thereof intermediate said first and second ends defining an exterior peripheral stabilizer surface, said coring bit being characterized by said coring face being electro-negative with respect to the standard reduction potential of steel. ### Claim 26 (depends on 25) The drill bit according to claim 25, being characterized further by said intermediate portion of said coring bit also being electro-negative with respect to the standard reduction potential of steel. ### Claim 27 (depends on 25) The coring bit according to claim 25, being characterized further by at least a portion of said second end of said coring bit defining a tubular body being electro-positive with respect to the standard reduction potential of steel. ### Claim 28 (depends on 25) The coring bit according to claim 25, being characterized further by at least a portion of said second end of said coring bit defining a tubular body having the same degree of electro-negativity as the standard reduction potential of steel. ### Claim 29 (depends on 25) The coring bit according to claim 25, wherein said second end of said coring bit defining a tubular body comprises a shank and a threaded pin. ### Claim 30 (depends on 25) The coring bit according to claim 25, being characterized further by said coring face having been subjected to a gas nitriding process to cause said coring face to be electro-negative with respect to the standard reduction potential of steel. ### Claim 31 (depends on 26) The coring bit according to claim 26, being characterized further by said intermediate portion having been subjected to a gas nitriding process to cause said intermediate portion to be electro-negative with respect to the standard reduction potential of steel. ### Claim 32 (depends on 27) The coring bit according to claim 27, being characterized further by said at least a portion of said second end having been subjected to a galvanizing process to cause said at least a portion of said second end to be electro-positive with respect to the standard reduction potential of steel. ### Claim 33 A stabilizer for use in a drill string, comprising: a steel stabilizing body having first and second ends adapted to be threaded into a drill string; said steel stabilizing body having a portion intermediate said first and second ends sized to bear against the borehole wall, said intermediate portion being electro-negative with respect to the standard reduction potential of steel. ### Claim 34 (depends on 33) The stabilizer according to claim 33, wherein each of said first and second ends comprises a shank and a threaded pin. ### Claim 35 (depends on 33) The stabilizer according to claim 33, wherein each of said first and second ends comprises a shank having female threads. ### Claim 36 (depends on 33) The stabilizer according to claim 33, wherein said first end comprises a shank and a threaded pin, and said second end comprises a shank having female threads. ### Claim 37 (depends on 33) The stabilizer according to claim 33, being characterized further by said intermediate portion having been subjected to a gas nitriding process to cause said intermediate portion to be electro-negative with respect to the standard reduction potential of steel. ### Claim 38 (depends on 33) The stabilizer according to claim 33, being characterized further by at least a portion of at least one of said first and second ends being electro-positive with respect to the standard reduction potential of steel. ### Claim 39 (depends on 38) The stabilizer according to claim 38, being characterized further by said at least a portion of at least one of said first and second ends having been subjected to a galvanizing process to cause said at least a portion of at least one of said first and second ends to be electro-positive with respect to the standard reduction potential of steel. ### Claim 40 (depends on 38) The stabilizer according to claim 38, being characterized further by said at least a portion of each of said first and second ends having been subjected to a galvanizing process to cause said at least a portion of each of said first and second ends to be electro-positive with respect to the standard reduction potential of steel. ### Claim 41 (depends on 33) The stabilizer according to claim 33, being characterized further by said at least a portion of at least one of said first and second ends having the same degree of electro-negativity as the standard reduction potential of steel. ### Claim 42 A borehole enlarging apparatus for use in a drill string, comprising: a steel body having first and second ends adapted to be threaded into a drill string; said steel body having expandable cutter arms mounted in a portion of said steel body intermediate said first and second ends, said intermediate portion being electro-negative with respect to the standard reduction potential of steel. ### Claim 43 (depends on 42) The borehole enlarging apparatus according to claim 42, wherein each of said first and second ends comprises a shank and a threaded pin. ### Claim 44 (depends on 42) The borehole enlarging apparatus according to claim 42, wherein each of said first and second ends comprises a shank having female threads. ### Claim 45 (depends on 42) The borehole enlarging apparatus according to claim 42, wherein said first end comprises a shank and a threaded pin, and said second end comprises a shank having female threads. ### Claim 46 (depends on 42) The borehole enlarging apparatus according to claim 42, being characterized further by said intermediate portion having been subjected to a gas nitriding process to cause said intermediate portion to be electro-negative with respect to the standard reduction potential of steel. ### Claim 47 (depends on 42) The borehole enlarging apparatus according to claim 42, being characterized further by at least a portion of first and second ends being electro-positive with respect to the standard reduction potential of steel. ### Claim 48 (depends on 47) The borehole enlarging apparatus according to claim 47 being characterized further by said at least a portion of at least one of said first and second ends having been subjected to a galvanizing process to cause said at least a portion of at least one of said first and second ends to be electro-positive with respect to steel. ### Claim 49 (depends on 47) The borehole enlarging apparatus according to claim 47, being characterized further by said at least a portion of each of said first and second ends having been subjected to a galvanizing process to cause said at least a portion of each of said first and second ends to be electro-positive with respect to the standard reduction potential of steel. ### Claim 50 (depends on 42) The borehole enlarging apparatus according to claim 42, being characterized further by said at least a portion of at least one of said first and second ends having the same degree of electro-negativity as the standard reduction potential of steel. ### Claim 51 A downhole apparatus adapted to be connected in a drill string, comprising: a steel body; said steel body having at least one end adapted to be threadedly connected to said drill string, said apparatus being characterized by at least a portion of said steel body being electro-negative with respect to the standard reduction potential of steel. ### Claim 52 (depends on 51) The downhole apparatus according to claim 51, being characterized further by at least a portion of said at least one end having the same degree of electro-negativity as the standard reduction potential of steel. ### Claim 53 (depends on 51) The downhole apparatus according to claim 51, being characterized further by at least a portion of said at least one end being electro-positive with respect to the standard reduction potential of steel. ### Claim 54 A downhole apparatus combination adapted to be connected in a drill string, comprising: a first steel body, said first steel body being adapted to be threadedly connected into said drill string; a second steel body, said second steel body being adapted to be threadedly connected into said drill string, said combination being characterized by at least a portion of one of said bodies being electro-negative with respect to the standard reduction potential of steel. ### Claim 55 A downhole apparatus combination adapted to be connected in a drill string, comprising: a first steel body, said first steel body being adapted to be threadedly connected into said drill string; a second steel body, said second steel body being adapted to be threadedly connected into said drill string, said combination being characterized by at least a portion of one of said bodies being electro-positive with respect to the standard reduction potential of steel. ### Claim 56 A downhole apparatus combination adapted to be connected in a drill string, comprising: a first steel body, said first steel body being adapted to be threadedly connected into said drill string; a second steel body, said second steel body being adapted to be threadedly connected into said drill string, said combination being characterized by at least a portion of said first body being electro-negative with respect to the standard reduction potential of steel, and by at least a portion of said second body being electro-positive with respect to the standard reduction potential of steel. ### Claim 57 A downhole apparatus adapted to be connected in a drill string, comprising: a steel body; said steel body having at least one end adapted to be threadedly connected to said drill string, said apparatus being characterized by at least a portion of said steel body being electro-positive with respect to the standard reduction potential of steel. ### Claim 58 (depends on 57) The downhole apparatus according to claim 57, being characterized further by at least a portion of said steel body having the same degree of electro-negativity as the standard reduction potential of steel. ### Claim 59 (depends on 57) The downhole apparatus according to claim 57, being characterized further by at least a portion of said steel body being electro-negative with respect to the standard reduction potential of steel.