Drill string deflector sub

Details Drill string deflector sub Drill string deflector sub

1998-12-18

2001-11-20

Will, Thomas B. (Department: 3671)

Boring or penetrating the earth

Means traveling with tool to constrain tool to bore along...

C175S076000

Reexamination Certificate

active

06318481

ABSTRACT:

This invention pertains to apparatus for use on drill strings near the drill head to deflect the progressing well bore from an existing centerline. More specifically, the apparatus reacts to commands from the surface to extend and retract a well bore wall engaging element from the apparatus to produce a side load on a drill head to deflect the well bore.
BACKGROUND
The need for control of the direction in which a bore hole progresses has always been desirable and the ability to reliably and accurately do so has improved markedly in recent years. With the advent of measurement while drilling, or MWD, directional drilling control became more frequently a drilling requirement.
Passive directional controls, applied historically, include the use and placement of stabilizers along the lower sections of the drill collars. Success of this system depended largely upon the drillers skill and experience. That approach is often considered more art than science.
Active directional controls, more recently employed, apply positive influence upon the drilling assembly and include the rather cumbersome use of whipstocks. More complex and about as capable are the systems for bending the active drill string just above the drill head. Hinge type devices are effective but tend to weaken the drill string. Permanently bent elements of the drill string usually require the use of drilling motors. Drilling motors, generally, do not have the ability to fully utilize the available hydraulic horsepower of the mud stream but, overall, their use is often economically advantageous.
When permanently bent sections of drill string are used, drilling motors are normally involved and straight hole drilling is usually accomplished by rotating the drill string. That rather deranges the force vectors in the lower end of the drill string and the drill head. In some formations, rotating a bent string produces unacceptable stresses in the lower drill string assembly.
It is desirable to provide means to deflect the course of the progressing drill head, only when needed for directional control, by directing a lateral force between the drill string and the well bore wall in the vicinity of the drill head. The reaction force at the drill head tends to deflect the course of the advancing bore hole. The drill string remains generally straight to better accept bit load vectors directed along the general centerline of the drill string. Rotary drilling without down hole motors can proceed if the side loading contrivance can remain rotationally stationary relative to earth while the drill string rotates.
It is therefore an object of this invention to provide means to extend an element from the drill string to engage, and apply a deflecting lateral force against, the well bore wall, and to retract the element when the lateral deflection is no longer needed.
It is still another object of this invention to provide apparatus that can be actuated to change between directional and straight hole drilling configuration by manipulation of the drilling fluid flow rate controls at the surface.
It is yet another object of this invention to provide apparatus to apply a deflection producing lateral force between a well bore wall and a drill string and maintain the lateral force producing means stationary while the drill string rotates to drill.
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.
SUMMARY OF INVENTION
The apparatus functions as a length element of the drill string, near the drill head. A side loading element of the general configuration of a stabilizer blade is movably situated to extend from, and retract into, the outer wall of the apparatus. A hydraulic cylinder, powered by drilling fluid pressure drop across a control valve, moves to cause the element to extend. When the extending force is removed, by reduction of drilling fluid flow, a spring reverses the movement of the cylinder piston to retract the element. The movement that retracts the element also engages a clutch to rotationally secure the housing to the arbor. The control valve is, preferably, responsive to preselected manipulation of drilling fluid flow rate controls at the surface. By actuation of different drilling fluid flow rate control processes, the fluid power is not applied to the cylinder and the spring retracts the element. In the preferred embodiment extension and retraction occurs on alternate occasions of increasing drilling fluid flow from a preselected lower flow rate, including no flow. The flow rate characteristic that controls is then the act of following a prior flow increase with another increase after reducing the flow rate. Otherwise stated, odd occasions of flow increase will extend the element and even occasions of flow rate increase will retract the element. Other valve actuating processes may be used to exercise controls, by design choices. Several suitable valve actuators are now in the art.
The side loading element is carried by a housing of generally cylindrical configuration that is free to rotate about the periphery of the drill string. Rotary drilling can proceed while the housing is rotationally stationary. The housing is arranged to be rotationally locked to the drill string for purposes of orientation and straight hole drilling. The housing locking state is coincident with retraction of the loading element. Once positioned rotationally, a signal is generated at the surface to activate the valve to extend the loading element, which also unlocks the housing. The rotationally stationary, or unlocked, housing moves axially with the drill string as the well is deepened. Eventually, the orienting process needs to be repeated to assure that the side loading element is properly oriented.
In some cases, a stabilizer is best used between the side loading element and the drill head. In such cases the stabilizer acts as a fulcrum and the drill head is deflected in the direction of the side loading element. Such use of stabilizers is in the art.


REFERENCES:
patent: 3595326 (1971-07-01), Claycomb
patent: 4572305 (1986-02-01), Swietlik
patent: 4655299 (1987-04-01), Schoeffler
patent: 4715453 (1987-12-01), Falgout, Sr. et al.
patent: 4895214 (1990-01-01), Schoeffler
patent: 5553678 (1996-09-01), Barr et al.
patent: 5941321 (1999-08-01), Hughes
patent: 5979570 (1999-11-01), McLoughlin et al.

Affiliated with

Also associated with

Rating

Drill string deflector sub does not yet have a rating. At this time, there are no reviews or comments for this patent.

If you have personal experience with Drill string deflector sub, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Drill string deflector sub will most certainly appreciate the feedback.

Rate now

Comments { 0 }

Profile ID: LFUS-PAI-O-2599203