Boring or penetrating the earth – Processes – Boring curved or redirected bores
Reexamination Certificate
2000-01-28
2001-11-27
Dang, Hoang (Department: 3672)
Boring or penetrating the earth
Processes
Boring curved or redirected bores
C175S365000, C175S376000, C175S398000, C175S399000
Reexamination Certificate
active
06321858
ABSTRACT:
TECHNICAL FIELD
The invention relates to a method and bit for directional drilling.
BACKGROUND OF THE INVENTION
Directional boring apparatus or trenchless drills for making holes through soil are well known. The directional borer generally includes a series of drill rods joined end to end to form a drill string. The drill string is pushed or pulled though the soil by means of a powerful device such as a hydraulic cylinder. The drill string may be pushed and rotated at the same time. A spade, bit or head having one or more angled faces configured for boring is disposed at the end of the drill string and may include an ejection nozzle for water or drilling mud to assist in boring.
In one known directional boring system, the drill bit is pushed through the soil without rotation in order to steer the tool by means of the angled face, which is typically a forwardly facing sloped surface. For rocky conditions, a row of teeth may be added to the drill bit and the bit operated in the manner described in Runquist et al. U.S. Pat. No. 5,778,991. Other toothed bits for directional boring through rock are shown in European Patent Applications Nos. EP 0 857 852 and EP 0 857 853, Cox U.S. Pat. No. 5,899,283, Skaggs U.S. Pat. No. 5,647,448 and Stephenson U.S. Pat. No. 5,799,740. Steering systems for use with these devices require keeping track of the angle of rotation of the sloped face of the bit and/or the teeth.
According to anothervknown system, a transmitter or sonde mounted in a tubular housing is mounted behind and adjacent to the bit and sends a signal that indicates the angle of rotation of the bit. The sonde is mounted in a predetermined alignment relative to the steering portion of the bit. Since the sonde housing is generally made of steel, a series of longitudinal slots or windows are provided through the wall of the sonde housing to permit transmission of the signal.
Boring machines such as the foregoing have difficulty penetrating cobble soil conditions where smalls stones are mixed in with soil. Mud motor driven boring machines presently available often provide the best penetration through cobble, but are highly expensive and difficult to run. The mud required to drive the mud motor must be supplied in large quantity and the motor itself must be completely rebuilt after a relative short useful life. A need persists for a directional boring bit that can handle a wide variety of soil conditions including cobble, and which can, when necessary, drill through solid rock. To date, no single bit design can perform all of these functions both effectively and economically.
SUMMARY OF THE INVENTION
The present invention provides an improved drill bit for directional drilling. The bit of the invention includes a housing or headpiece having means at a rear end thereof for mounting the bit on a trailing component of a drill head, and passages for ejection of drilling fluid into a borehole. Such means may, for example, be a threaded projection or cavity or a splined projection or cavity as described below, among others. A first axle is mounted to extend forwardly from a front end of the housing, and a first roller is rotatably mounted on the first axle. The first roller has cutting projections such as carbide studs thereon and extends outside of the outer diameter of the housing by a distance which defines the size of the borehole when the drill bit is rotated over 360 degrees. A second axle is mounted to extend from the front end of the housing, and a second roller is rotatably mounted on the second axle at a position offset from the first axle. The second roller extends slightly outside of the outer diameter of the housing, but by a distance less than the distance the first roller extends outside of the housing. The second roller is configured to provide a reaction surface for the first roller as the first roller bores the borehole with the cutting projections.
A method for boring using such a bit includes rotating the bit continuously over 360° to bore straight ahead with the first and second rollers in contact with the wall of the borehole, and pivoting the first roller back and forth over a limited arc of rotation with the first and second rollers in contact with the wall of the borehole in order to deviate the borehole in the direction of the arc. Fluid is ejected from orifices in the front of the housing to lubricate the bore during drilling. These and other aspects of the invention are described in detail below.
REFERENCES:
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patent: 3094177 (1963-06-01), Williams, Jr.
patent: 3825081 (1974-07-01), McMahon
patent: 4763736 (1988-08-01), Varel, Sr.
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patent: 5242026 (1993-09-01), Deken et al.
patent: 5392868 (1995-02-01), Deken et al.
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patent: 5628585 (1997-05-01), Parish, II et al.
patent: 5839525 (1998-11-01), Hoffmaster et al.
patent: 5924500 (1999-07-01), Puttmann
patent: 5941322 (1999-08-01), Stephenson et al.
Rhino Rock Bit, website—http://www.ditchwitch.com/Equipment/Parts/Downhole13Tools/bits/rhino.htm, 1 page.
Sharewell—Directional Drilling Systems, “The Lo-Torque Hole Opener” brochure, 11 pgaes.
Crane Robert F.
Wentworth Steven W.
Dang Hoang
Earth Tool Company L.L.C.
Intellectual Property Law, P.C.
Meyers Philip G.
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