Boring or penetrating the earth – Cutter element laterally shiftable below ground – With shifting mechanism spring biased to operative position
Reexamination Certificate
2000-03-27
2001-09-11
Tsay, Frank S. (Department: 3672)
Boring or penetrating the earth
Cutter element laterally shiftable below ground
With shifting mechanism spring biased to operative position
C175S279000, C166S381000
Reexamination Certificate
active
06286614
ABSTRACT:
BACKGROUND OF THE INVENTION
The present invention relates generally to drilling, milling and similar operations performed in conjunction with a subterranean well and, in an embodiment described herein, more particularly provides a motion compensator for drilling from a floater.
It is frequently desirable to isolate a cutting device, such as a drill bit or a mill, from the motion of a tubular string on which the cutting device is carried. For example, where a cutting operation is being performed from a floating rig (sometimes referred to as a “floater”), the tubular string suspended from the floater may rise and fall due to a heaving motion of the rig. Some floaters may be equipped with devices known as heave motion compensators, but these devices are not typically capable of removing all rising and falling motion from a suspended tubular string.
In some circumstances, accurate axial advancement of the cutting device in the well may be required. This accurate advancement is compromised by the rising and falling of the tubular string. For example, the cutting device may be a mill which may be damaged if the mill suddenly impacts a structure downhole. Of course, many other circumstances also require accurate axial advancement of a cutting device, whether the operations are performed from a floater or a landbased rig.
From the foregoing, it can be seen that it would be quite desirable to provide a motion compensator which permits accurate axial advancement of a cutting device. It is accordingly an object of the present invention to provide such a motion compensator and associated methods of controlling displacement of a cutting device in a well.
SUMMARY OF THE INVENTION
In carrying out the principles of the present invention, in accordance with an embodiment thereof, a motion compensator is provided which includes an anchoring device and an axial advancement device. Associated methods are also provided.
In one aspect of the present invention, the anchoring device includes a slip and a shoulder engageable with an abutment in the well. The engagement between the shoulder and the abutment axially positions the motion compensator in the well. The slip extends outwardly from the motion compensator to grip a structure in the well and thereby prevent rotation of the motion compensator.
In another aspect of the present invention, the anchoring device includes a key member which is outwardly extendable to engage a recess in the well, thereby axially and rotationally anchoring the motion compensator in the well. The motion compensator may be provided with a diameter sensing device so that, when the device senses a predetermined diameter in the well, the key member is extended outwardly.
In yet another aspect of the present invention, the advancement device includes a restroking or recocking mechanism. The mechanism permits the cutting device to be withdrawn from the structure being cut, for example, if the cutting device stalls, etc., and then again advanced in a controlled manner toward the structure to be cut. In one embodiment, the mechanism includes ratcheting members, and in another embodiment, the mechanism includes a telescoping outer housing of the motion compensator.
These and other features, advantages, benefits and objects of the present invention will become apparent to one of ordinary skill in the art upon careful consideration of the detailed description of representative embodiments of the invention hereinbelow and the accompanying drawings.
REFERENCES:
patent: 3747674 (1973-07-01), Murray
patent: 4842082 (1989-06-01), Springer
patent: 5363931 (1994-11-01), Moriarty
patent: 5697449 (1997-12-01), Hennig et al.
patent: B1 4270606 (1986-01-01), McStravick et al.
SKF Planetary Roller Screw Catalog, Three Pages, undated.
Bowling John S.
Gano John C.
Halliburton Energy Service,s Inc.
Herman Paul I.
Smith Marlin R.
Tsay Frank S.
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