Boring or penetrating the earth – With means movable relative to tool or shaft to control... – Valve prevents upward flow
Reexamination Certificate
1999-09-07
2001-06-05
Neuder, William (Department: 3672)
Boring or penetrating the earth
With means movable relative to tool or shaft to control...
Valve prevents upward flow
C166S237000, C192S03000R, C192S046000, C192S069810
Reexamination Certificate
active
06241032
ABSTRACT:
This invention pertains to a one-way clutch apparatus for use on drill strings to prevent rotational backlash of the drill string, from suddenly released torque loads, from unscrewing the bottom hole assembly. The clutch transmits torque in the forward, or drilling, direction but free wheels in the reverse direction. The apparatus can be used above or below a Measurement While Drilling (MWD) system, or anywhere below the Kelly.
BACKGROUND
During rotary drilling, the torque applied to the drill head can wind up the drill string several turns, distributed over the drill string length. This is in turns that the drill head lags the rotary table input at the surface. If the drill head is suddenly lifted off bottom, the torque at the drill head approaches zero and the drill head races forward as the string rotationally unwinds. The lower end of the unwinding drill string can overshoot the neutral position and cause torque in the opposite direction. The reversal from the overrun position tends to unscrew the bottom hole assembly from the drill string. The tendency to unscrew connections can take place anywhere along the drill string. That sequence of events can be prevented under most normal circumstances by an experienced driller, by avoiding sudden removal of bit load while the string is delivering torque to the drill head. Sudden release of bit load, due to unexpected circumstances, sometimes happens. The lower end assembly unscrewed from the drill string and loose down hole is a classic drilling problem that is expensive to correct.
SUMMARY OF INVENTION
The apparatus is a one-way clutch in a housing which is part of a continuing drill string. The housing has to selectively permit relative rotation between upper and lower parts of the housing and is rugged enough for drilling activity while retaining fluid tightness to confine fluid moving down the drill string bore. The bearings rotationally connecting the two major housing parts seldom rotate and are situated for column rigidity of the housing. A clutch member, preferably with teeth for engagement, is biased by weight, spring, or piston loads for axial movement in one part of the housing to urge it into engagement with matching clutch teeth in the mating portion of the housing. The movable clutch member is preferably spline connected to its respective portion of the housing for torque transmission when the teeth are engaged. Splines are easily managed in manufacture and maintenance activity but there are many means for rotationally connecting a clutch element, yet allow limited axial movement for clutch action.
A fluid conducting bore extends through the housing, which has connector arrangements at the ends for connection to the continuing drill string.
An optional signal generator in the fluid conducting bore produces a pressure change in the flowing drilling fluid to indicate, by a drilling fluid pressure increase, when the clutch is disengaged. The pressure increase is detectable at the surface, in the drilling fluid circuit, to alert the driller of the down hole condition. The signal pressure drops back to normal when the clutch is again engaged.
The preferred clutch is a saw toothed arrangement that can, in one option, engage in only one position of relative rotation between the upper and lower portions of the apparatus. This option is used when the apparatus is situated below a MWD system.
For use in unusual circumstance, when torque may need to be transmitted down the drill string in both rotational directions, optional provisions permit the apparatus to be locked rotationally by a spear dropped down the drill string bore. Such spears are well established in the well drilling art and are normally recoverable by wire line from the surface. A spear lowered through the drill string to a receiving device down hole to accomplish a planned effect is in the art of downlink command communication signal activity. The spear is usually recoverable by wire line.
It is an object of the invention to provide a drill string clutch that will prevent the drill string from applying a rotational force to the drill string that can unscrew the drill string tool joints.
It is another object of the invention to provide a signal in the drilling fluid stream that will alert a driller at the surface that the clutch is disengaged down hole.
It is another object of the invention to provide a clutch that will re-engage only in one relative rotational position between portions of the housing to orient the upper portion of the drill string with the lower portion of the drill string.
It is still another object of the invention to provide means to rotationally lock the apparatus so that the clutch will stay engaged when torque is applied in either direction.
These and other objects, advantages, and features of this invention will be apparent to those skilled in the art from a consideration of this specification, including the attached claims and appended drawings.
REFERENCES:
patent: 3908453 (1975-09-01), Jeter
patent: 4391328 (1983-07-01), Aumann
patent: 4632193 (1986-12-01), Geczy
patent: 4848531 (1989-07-01), Gray et al.
patent: 5673764 (1997-10-01), Falgout, Sr.
patent: 5775444 (1998-07-01), Falgout, Sr.
patent: 5918690 (1999-07-01), Halley
patent: 6082457 (2000-07-01), Best et al.
Jeter John D.
Neuder William
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