Single-wire guidance system for drilling boreholes
First Claim
1. A method for guiding the drilling of a borehole along a path below the Earth'"'"'s surface comprising:
- positioning an elongated electrically conductive and insulated guidewire adjacent a desired path to be followed by a subsurface borehole to be drilled, the desired path extending through a resultant static magnetic field including at least the Earth'"'"'s apparent magnetic field;
connecting a first terminal of a current source to a first end of said guidewire;
connecting a second end of said guidewire to electrical ground at the Earth'"'"'s surface;
connecting a second terminal of said current source to electrical ground at the Earth'"'"'s surface to provide a return ground path for current flowing in the guidewire;
supplying from said source a current of known amplitude in a first direction to said first end of said guidewire to cause said current to flow to said electrical ground at said second end of said guidewire and to return through the Earth to said second terminal of said source for a first period of time to produce a changes in said resultant static magnetic field in the region of said desired path;
measuring, at a subsurface borehole being drilled through the Earth along said Path, vector components of said resultant static magnetic field; and
;
determining, from changes in said vector components of said resultant magnetic field, the distance and direction from said borehole being drilled to said guidewire.
2 Assignments
0 Petitions
Accused Products
Abstract
A single guide wire system for use in continually directional drilling of boreholes, includes a guidewire extending generally parallel to the desired path of the borehole. The guidewire is connected at a first end to one side of a reversible source of direct current, and at a second end to ground. A second side of the DC source is also connected to ground. A known current flow in a first direction for a first period of time and in a second direction for a second period of time produces corresponding static magnetic fields in the region of the borehole. The vector components of the fields are measured in the borehole by a 3-axis magnetometer, and from these vector components the effects of the Earth'"'"'s magnetic field are canceled and the distance and direction from the borehole to the guidewire are determined. These values permit control of further drilling of the borehole along a desired path.
108 Citations
14 Claims
-
1. A method for guiding the drilling of a borehole along a path below the Earth'"'"'s surface comprising:
-
positioning an elongated electrically conductive and insulated guidewire adjacent a desired path to be followed by a subsurface borehole to be drilled, the desired path extending through a resultant static magnetic field including at least the Earth'"'"'s apparent magnetic field; connecting a first terminal of a current source to a first end of said guidewire; connecting a second end of said guidewire to electrical ground at the Earth'"'"'s surface; connecting a second terminal of said current source to electrical ground at the Earth'"'"'s surface to provide a return ground path for current flowing in the guidewire; supplying from said source a current of known amplitude in a first direction to said first end of said guidewire to cause said current to flow to said electrical ground at said second end of said guidewire and to return through the Earth to said second terminal of said source for a first period of time to produce a changes in said resultant static magnetic field in the region of said desired path; measuring, at a subsurface borehole being drilled through the Earth along said Path, vector components of said resultant static magnetic field; and
;determining, from changes in said vector components of said resultant magnetic field, the distance and direction from said borehole being drilled to said guidewire. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9)
-
-
10. A method for guiding the drilling of a borehole along a path below the Earth'"'"'s surface, comprising:
-
defining a path to be followed by a subsurface borehole from an entrance location to an exit location, the path extending through a resultant static magnetic field including at least the Earth'"'"'s magnetic field; positioning an elongated electrically conductive and insulated guidewire at the Earth'"'"'s surface adjacent at least a portion of said path near said exit location; connecting a first end of said guidewire remote from said exit location to electrical ground by way of an uninsulated ground wire on the Earth'"'"'s surface extending in a direction perpendicular to said guidewire; connecting a second end of said guidewire near said exit location to a first terminal of a current source; connecting a second terminal of said current source to electrical ground near said exit location to provide a return ground path for current flowing in said guidewire; supplying from said source a current of known amplitude in a first direction to said second end of said guidewire to cause current to flow to electrical ground through said ground wire and to return through-the Earth to said second terminal of said source for a first predetermined period of time to produce changes in said resultant static magnetic field; measuring, at a subsurface borehole being drilled along said path, vector components of said resultant magnetic field; and determining, from changes in said vector components of said resultant magnetic field, the distance and direction from said borehole being drilled to said guidewire. - View Dependent Claims (11, 12, 13, 14)
-
Specification