BOREHOLE ELECTROLYTIC POWER SUPPLY

• US 3,876,471 A
• Filed: 09/12/1973
• Issued: 04/08/1975
• Est. Priority Date: 09/12/1973
• Status: Expired due to Term

• Current Assignee: Baroid Technology Incorporated (Halliburton Company)
• Original Assignee: Jack W. Jones
• Inventors: Jones, Jack W.
• Primary Examiner(s): Strecker, Gerard R.
• Application Number:
  US05/396,978
• Time in Patent Office: 573 Days
• Field of Search: 324/1,2,10 136/1R,1M 73/152,153 204/148,197,248
• US Class Current: 175/93
• CPC Class Codes: E21B 17/00 Drilling rods or pipes; Flexible drill strings; Kellies; Drill collars; Sucker rods; Cables; Casings; Tubings
• CPC Class Codes: E21B 41/0085 Adaptations of electric power generating means for use in boreholes
• CPC Class Codes: E21B 47/12 Means for transmitting measuring-signals or control signals from the well to the surface, or from the surface to the well, e.g. for logging while drilling
• CPC Class Codes: H01M 6/32 activated through external addition of electrolyte or of electrolyte components

Abstract

Power supply apparatus for generating electrical energy for a sustained period of time within the environment of an earth borehole filled with drilling mud. The power supply is used in a downhole well logging system for supplying electrical energy to circuitry located down within the borehole and includes an elongate magnesium electrode having a plurality of circumferentially spaced, longitudinally extending slots formed therein. The electrode is located in a special sub within the drill pipe and a potential difference is produced between the magnesium electrode and the walls of the steel drill pipe due to electrolytic decay of the metals, when a conductive drilling mud is located therebetween.

Claims

1. A downhole power source for generating electrical energy within an earth borehole, comprising:

a hollow cylindrical drilling pipe;

a cylindrical electrode positioned coaxially within said pipe to define an annular space therebetween and having a plurality of circumferentially spaced, longitudinally extending slots formed therein, said electrode being formed from a material having a different electrochemical potential than said drilling pipe;

a plurality of radially extending, circumferentially-spaced struts between said pipe and said electrode to hold said electrode in position;

means for insulating said electrode from said drilling pipe; and

a conductive drilling mud located in the annular space between said electrode and said drilling pipe to produce an electrical potential

2. A downhole power source for generating electrical energy within an earth borehole as set forth in claim 1 wherein said drilling pipe is made of

3. A downhole power source for generating electrical energy within an earth borehole, as set forth in claim 1, which also includes:

means for moving said conductive drilling mud through said annular space to

4. A downhole power source for generating electrical energy within an earth borehole, as set forth in claim 1, which also includes:

a d. c. to d. c. converter having its input terminals connected between said electrode and said drilling pipe to amplify the potential

5. A downhole power source for generating electrical energy within an earth borehole, as set forth in claim 1, wherein, the resistivity of said conductive drilling mud is less than 15

6. A special telemetry sub for inclusion in the drill pipe string of an earth borehole drilling apparatus, said sub comprising:

a section of hollow steel drill pipe having threads at either end for engagement with drill pipes within a string;

an elongate cylindrical telemetry instrument package positioned coaxially within said pipe to define an annular space therebetween, said package being held in position by a plurality of radially extending, circumferentially spaced struts;

a cylindrical electrode attached to and insulated from the end of said coaxial instrument package, said electrode being formed from a material having a different electrochemical potential than said drill pipe;

means for connecting to said instrument package the potential generated between said electrode and said drill pipe when a conductive drilling mud

7. A special telemetry sub as set forth in claim 6 wherein:

said telemetry instrument package includes a d. c. to d. c. converter having the input thereof connected across said drill pipe and said electrode to power said package from the potential difference

8. A special telemetry sub as set forth in claim 6 wherein:

9. A special telemetry sub as set forth in claim 8 wherein:

said cylindrical electrode includes a plurality of circumferentially spaced, longitudinally extending slots formed therein to increase the effective surface area thereof.