LOW FREQUENCY DRILL BIT APPARATUS AND METHOD OF LOCATING THE POSITION OF THE DRILL HEAD BELOW THE SURFACE OF THE EARTH

• US 3,828,867 A
• Filed: 05/15/1972
• Issued: 08/13/1974
• Est. Priority Date: 05/15/1972
• Status: Expired due to Term

• Current Assignee: Albert A. Elwood
• Original Assignee: Albert A. Elwood
• Inventors: Elwood, Albert A.
• Primary Examiner(s): Brown, David H.
• Application Number:
  US05/253,544
• Time in Patent Office: 820 Days
• Field of Search: 175/1,61,73,40,45,24 102/21.6
• US Class Current: 175/45
• CPC Class Codes: E21B 41/0014 Underwater well locating or reentry systems
• CPC Class Codes: E21B 47/04 Measuring depth or liquid level
• CPC Class Codes: E21B 47/09 Locating or determining the position of objects in boreholes or wells , e.g. the position of an extending arm; Identifying the free or blocked portions of pipes
• CPC Class Codes: E21B 7/04 Directional drilling
• CPC Class Codes: G01S 1/02 using radio waves G01S19/00 takes precedence
• CPC Class Codes: G01V 15/00 Tags attached to, or associated with, an object, in order to enable detection of the object record carriers for use with machines having a detectable tag or marker G06K19/00

Abstract

An earth drill bit locating apparatus and method of detecting and locating the position of a drill bit below the surface of the earth utilizing very low frequency electromagnetic energy. The apparatus includes a transmitter located adjacent the drill bit for transmitting a very low-frequency electromagnetic wave below 5,000 Hz and a plurality of receivers including antennae placed adjacent to the earth'"'"''"'"'s surface for detecting the low-frequency wave and computing the position of the drill bit by triangulation. Each receiver is a directional indicating receiving means for obtaining raw data in order to display and plot the movement of the drill head as it moves into the earth. The transmitter is powered by an alternator driven by a turbine in the mud supply conduit or collar just above the bit. The drill collar is fitted with electrodes or wire loops which are connected to the transmitter output to cause the drill collar to act as an electric or magnetic radiating dipole.

Claims

1. An apparatus for locating a drill bit within the earth'"'"''"'"'s crust relative to a predetermined reference position comprising:

a low frequency electro-magnetic wave transmitter within the earth for transmitting an output signal below 10,000 Hertz;

a power supply connecTed to said transmitter;

at least two directional indicating low frequency receivers in conductive communication with the earth for detecting the transmitted low frequency signals; and

analyzing means coupled to said receivers for analyzing the low frequency received signals providing information giving the reference location of said transmitter relative to said predetermined reference position; and

a drill rig including a drive means, a drill string connected to said drive means, and a drill bit connected at the free end of said drill string, said low frequency electro-magnetic transmitter coupled to said drill string, adjacent said drill bit.

2. A drill location apparatus, as set forth in claim 1, wherein said transmitter includes:

an alternator;

a turbine driveably connected to said alternator;

a mud supply conduit coupled within said drill string, said turbine disposed within said mud supply conduit.

3. A drill location apparatus as set forth in claim 2 including:

indicating means coupled to said analyzing means for providing a visual display of said drill bit location.

4. A drill bit location apparatus as set forth in claim 3, wherein:

said receivers include a housing in contact with said earth surface, a fluid medium within said housing having a conductivity similar to that of the surrounding earth, said receiver antennas immersed in said medium.

5. A drill location apparatus as set forth in claim 4, wherein:

the lower end of said drill string is connected to the transmitter output to cause the lower end of the drill string to act as an electrical dipole antenna.

6. A method for detecting the location of a drill bit within the surface of the earth by transmitting low frequency electro-magnetic wave energy with reference to a known predetermined reference location comprising the steps of:

transmitting a low frequency electro-magnetic wave below 5,000 Hertz within the earth'"'"''"'"'s surface from a drill bit located within the earth'"'"''"'"'s surface while simultaneously moving the drill bit within the earth'"'"''"'"'s surface to perform drilling;

receiving the transmitted low frequency electro-magnetic energy within the earth'"'"''"'"'s surface; and

comparing the received signals from the receivers with a known reference point location signal thereby determining the location of the transmitting source relative to the known reference point.

7. An apparatus for locating a drill bit within the earth'"'"''"'"'s crust relative to a predetermined reference position comprising:

a low frequency electro-magnetic receiver within the earth for receiving an electro-magnetic signal below 10,000 Hertz;

at least two low frequency electro-magnetic transmitters in conductive communication with the earth'"'"''"'"'s crust for transmitting low frequency signals;

a power supply connected to said transmitters;

an analyzing means coupled to said receiver for analyzing the low frequency received signals for providing information giving the reference location of said transmitters relative to said predetermined reference location; and

a drill rig including a drive means, a drill string connected to said drive means, and a drill bit connected at the end of said drill string, said low frequency electro-magnetic receiver coupled to said drill string.