Boring or penetrating the earth – Automatic control – Of boring means including a below-ground drive prime mover
Patent
1993-04-28
1994-09-27
Bui, Thuy M.
Boring or penetrating the earth
Automatic control
Of boring means including a below-ground drive prime mover
175 76, E21B 708
Patent
active
053500288
DESCRIPTION:
BRIEF SUMMARY
BACKGROUND OF THE INVENTION
The invention relates to a device for adjusting the azimuth of the trajectory of a rotary-drilling bit.
In the case of rotary drilling, the drill bit is brought into rotation by a drill string one end of which located at the surface, is connected to a means for rotationally driving the drill bit.
The thrust load on the tool is also exerted by the drill string.
In current drilling techniques and particularly in oil drilling, there are well-known processes and devices for allowing a carrying out of a certain remote adjustment of the drill bit trajectory.
This adjustment may relate to a drift of the trajectory, with respect to the angle of this trajectory to the vertical or to the azimuth of the trajectory, to the angular position of a vertical drilling plane containing the axis of the hole or well, and/or with respect to a predetermined direction which is preferably the direction of the magnetic north.
The known devices and processes for adjusting the azimuth of the trajectory of a rotary-drilling bit require complex mechanical or electronic means comprising several mobile parts and imposing either a mechanical anchoring of part of the device inside the hole being drilled, or an electronic locating of the adjusting means with respect to the vertical drilling plane containing the axis of the hole or well in the process of being drilled.
The devices of the prior art which are used for adjusting the trajectory of a drill bit comprise means allowing the trajectory to be deflected in the wanted direction, which are connected to the drill string and which comprise bearing surfaces resting on the surface of the hole or wellbore, offset with respect to the drill string. When the means for adjusting the trajectory are set into operation, the bearing surfaces contact the inner surface of a hole in a wanted orientation.
Setting and actuating such adjusting devices is generally complex. It imposes the immobilization of said devices with respect to the wall of the wellbore and involves the use of a downhole motor.
SUMMARY OF THE INVENTION
The object of the invention is to propose a device for adjusting the azimuth of the trajectory of a rotary-drilling bit fastened to the end of a drill string rotating around the axis thereof arranged substantially along a vertical plane during drilling of a hole, the azimuth of the trajectory being defined by the angular position of the vertical plane or drilling plane with respect to a reference direction, with the device requiring no anchoring in the well and no locating of the adjusting means with respect to the drilling plane, and allowing an adjustment of the azimuth towards the right as well as towards the left of the drilling plane, in the direction of penetration of the drilling.
To that effect, the device according to the invention includes at least one drill string element integral with the drill string in rotation and fastened to the drill string in a vicinity of the drill bit, comprising, in cross-section parts whose outer bearing surfaces are arranged in a cylindrical surface having an axis merging or substantially merging with the axis of the drill string and a maximum diameter equal to or substantially equal to the nominal diameter of the hole, distributed around the axis of the drill string, so as to generate, during the rotation of the drill string, by reaction of the wall of the hole on the element, forces tipping the drill bit out of the drilling plane, either to the right or to the left of the drilling plane, during part of a full rotation of the drill string, and to hold the drill string substantially along the axis of the hole during the rest of the rotation.
BRIEF DESCRIPTION OF THE DRAWINGS
Other features and advantages of the invention will be clear from reading the description hereafter of several embodiments of a device for adjusting the azimuth of the trajectory of a rotary-drilling bit according to the invention, with reference to the accompanying drawings in which:
FIG. 1 is a schematic perspective view of a rotary-drillin
REFERENCES:
patent: 3092188 (1963-06-01), Farris
patent: 3825081 (1974-07-01), McMahon
patent: 3851719 (1974-12-01), Thompson et al.
patent: 4465147 (1984-08-01), Feenstra et al.
patent: 4804051 (1989-02-01), Ho
patent: 4854399 (1989-08-01), Zijsling
patent: 4880066 (1989-11-01), Steiginga et al.
patent: 4982802 (1991-01-01), Warren et al.
patent: 5168941 (1992-12-01), Krueger et al.
patent: 5181576 (1993-01-01), Askew et al.
Bui Thuy M.
Institut Francais du Pe'trole
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