Method for raising and lowering a drill string in a wellbore during drilling operations
A method is described for lowering a drill string formed with a plurality of sections of drill pipe and a drill bit at the lower end thereof into a deviated wellbore in which the weight of the drill bit rests along the lowerside of the deviated wellbore above the bottom of the wellbore, comprising the steps of: (a) rotating the drill pipe, (b) rotating the drill bit in the opposite direction from that of the drill pipe with a positive displacement downhole motor driven by the circulation of drilling fluid through the drill pipe and the annulus between the drill pipe and the wellbore, (c) lowering the drill string in the deviated borehole by dragging the drill pipe and drill bit along the lowerside of the deviated borehole, and (d) adjusting the flow rate of the circulating drilling fluid so as to rotate the drill bit at the same speed as that of the drill pipe. The drill bit remains rotationally stationary with respect to the wellbore and does not sidetrack into the lower side of the wall of the wellbore as the drill bit drags along the lower side of the wellbore during lowering of the drill string through the wellbore toward the bottom of the wellbore.
- Assignee:
- Mobil Oil Corp., New York, NY
- Patent Number(s):
- US 4646855
- OSTI ID:
- 6746661
- Country of Publication:
- United States
- Language:
- English
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DIRECTIONAL DRILLING
DRILL BITS
DRILL PIPES
DRILLING
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