Claims
- 1. A drilling tool for forming a borehole in an earth formation, comprising:
- (a) a drill bit at an end of the drilling tool, said drill bit upon rotation forming a first portion of the borehole having a first size;
- (b) a cutting device uphole of the drill bit, said cutting device upon rotation forming a second portion of the borehole which is greater in size than the first portion;
- (c) a drilling motor carried by the drilling tool, said drilling motor rotating the drill bit and the cutting device when a fluid under pressure is passed through the drilling motor, thereby forming the first and second portions of the borehole;
- (d) a first stabilizer between the drill bit and the cutting device for providing lateral stability and drilling direction guidance to the drill bit; and
- (e) a second stabilizer uphole of the cutting device, said second stabilizer including at least one member adapted to extend radially from the tool to contact the borehole to provide radial stability to the drilling tool during drilling of the borehole.
- 2. The drilling tool of claim 1, wherein said first stabilizer is one of (i) a substantially non-rotating stabilizer relative to the rotation of the drill bit and (ii) a rotating stabilizer.
- 3. The drilling tool of claim 1 further comprising a bend downhole of the drilling motor, said bend defining drilling direction of the borehole.
- 4. The drilling tool of claim 1 further comprising a kick-off sub in said tool for causing the drill bit and the cutter to drill a deviated borehole.
- 5. The drilling tool of claim 1, wherein the cutting device includes a plurality of radially movable arms, each said arm having a cutting element at an outer end of such arm to form the second portion of the borehole.
- 6. The drilling tool of claim 5 wherein each said arm is selectably movable between a retracted position and a cutting position.
- 7. The drilling tool of claim 6 wherein the arms are hydraulically operated between their respective retracted and cutting positions.
- 8. The drilling tool of claim 1, wherein the first stabilizer and the cutting device are integrated into a subassembly.
- 9. The drilling tool of claim 1, wherein the first stabilizer includes at least one fluid passageway for allowing the drilling fluid to pass between the drill bit and the cutting device.
CROSS REFERENCE TO RELATED APPLICATIONS
This application is based upon and claims priority from U.S. Provisional Application Ser. No. 60/030,127 filed on Nov. 4, 1996.
US Referenced Citations (16)
Foreign Referenced Citations (1)
Number |
Date |
Country |
WO 9409244 |
Apr 1994 |
WOX |