Method and apparatus for producing parallel boreholes
First Claim
1. A method of drilling parallel, generally horizontal boreholes, comprising:
- drilling a first borehole from an entrance location to an exit location;
pulling a guide cable into said first borehole while withdrawing the drill string used to drill the first borehole;
supplying a first guide current to said guide cable to produce a first magnetic field surrounding the guide cable;
drilling a second borehole within said magnetic field;
measuring selected parameters including parameters of said first magnetic field within said second borehole;
producing a second current in said second borehole and modulating said second current in accordance with the measured parameters to produce a corresponding modulated second magnetic field;
detecting said modulated second magnetic field at said guide cable to produce in said guide cable a third current corresponding to said measured parameters;
determining from said measured parameters the distance and direction from one of said boreholes to the other of said boreholes; and
controlling the direction of drilling of said second borehole in accordance with said determined distance and direction.
1 Assignment
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Accused Products
Abstract
A method and apparatus for steering boreholes for use in creating a subsurface barrier layer includes drilling a first reference borehole, retracting the drill stem while injecting a sealing material into the Earth around the borehole, and simultaneously pulling a guide wire into the borehole. The guide wire is connected to a source of current to produce a corresponding magnetic field in the Earth around the reference borehole while an adjacent borehole is drilled. The vector components of the apparent Earth'"'"'s magnetic field are measured vectors are used to determine the distance and direction from the borehole being drilled to the reference borehole in order to steer the borehole being drilled. The process is repeated to provide multiple parallel subsurface boreholes with adjacent boreholes being spaced sufficiently close together to insure overlapping of the sealing material to produce a continuous barrier. The magnetic field used for guidance is also used for signalling the steering tool electronic probe for controlling its measurement program. The guide wire is also used for an antenna to receive telemetry signals for data being sent by the probe to the surface.
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Citations
33 Claims
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1. A method of drilling parallel, generally horizontal boreholes, comprising:
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drilling a first borehole from an entrance location to an exit location; pulling a guide cable into said first borehole while withdrawing the drill string used to drill the first borehole; supplying a first guide current to said guide cable to produce a first magnetic field surrounding the guide cable; drilling a second borehole within said magnetic field; measuring selected parameters including parameters of said first magnetic field within said second borehole; producing a second current in said second borehole and modulating said second current in accordance with the measured parameters to produce a corresponding modulated second magnetic field; detecting said modulated second magnetic field at said guide cable to produce in said guide cable a third current corresponding to said measured parameters; determining from said measured parameters the distance and direction from one of said boreholes to the other of said boreholes; and controlling the direction of drilling of said second borehole in accordance with said determined distance and direction. - View Dependent Claims (2, 3, 4)
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5. Telemetry apparatus for parallel boreholes, comprising:
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a first borehole having an entrance location; a guide cable in said first borehole, said guide cable extending from said entrance location a predetermined distance into said first borehole; a source of current connected to said guide cable for producing a guide current in said guide cable and a corresponding magnetic guide field surrounding said cable; a drill stem for drilling a second borehole within said magnetic guide field; a sensor probe in said drill stem responsive at least to said magnetic guide field to produce output data signals corresponding to said magnetic guide field; a transmitter within said drill stem connected to said sensor probe for transmitting said data signals from said sensor to said guide cable; and means connected to said guide cable for receiving said data signal for use in controlling said drill stem. - View Dependent Claims (6, 7, 8, 9, 10, 11, 12, 13, 14)
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15. A method for producing substantially parallel boreholes, comprising:
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drilling a first borehole through the Earth using drilling equipment; pulling a guide cable into said first borehole by means of said drilling equipment simultaneously with drilling said first borehole for use in providing a reference magnetic field; retaining said cable in said first borehole as said drilling equipment is withdrawn, and drilling a second borehole guided by said magnetic field. - View Dependent Claims (16, 17, 18, 19, 20, 21, 22, 23, 24, 25)
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26. Telemetry apparatus for borehole, comprising:
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a drill stem for drilling a borehole; a sensor probe within said drill stem for producing data signals to be transmitted; a drill stem transmitter responsive to said data signals to produce a corresponding first magnetic field; a telemetry cable within and responsive to said first magnetic field to produce corresponding magnetically induced voltages; and a receiver connected to said cable to detect said voltages. - View Dependent Claims (27, 28, 29, 30, 31, 32, 33)
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Specification