Boring or penetrating the earth – Processes – Boring curved or redirected bores
Reexamination Certificate
1999-06-30
2001-04-03
Pezzuto, Robert E. (Department: 3671)
Boring or penetrating the earth
Processes
Boring curved or redirected bores
Reexamination Certificate
active
06209664
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a device for controlling the trajectory of a well drilled in the ground.
2. Description of the Prior Art
There are many well-known systems allowing control of the well inclination, for example by using a remote-controlled variable-diameter stabilizer. For azimuth correction, a downhole motor included in the drill string and coupled with a bent sub, whose direction correction action is done according to the spatial orientation in the plane of the bent sub, has been used in the trade for a long time. It is clear that, with this technique, the part of the string situated above the motor must be motionless in the borehole. This correction mode is referred to as <sliding> mode insofar as drilling progresses by <sliding>. This mode has many drawbacks, notably the fact that all of the drill string is not driven in rotation.
Directional drilling means that can work in a rotary mode have therefore been developed. Among the tools proposed, some exert a permanent or periodic controlled lateral stress on the wall of the well, in an opposite direction to the desired one, others exert an oriented flexion on the part of the pipes situated immediately above the tool, while allowing them to rotate. In any case, the necessity of maintaining the pipes rotating combined with that of controlling a fixed spatial orientation leads to sophisticated and expensive mechanical, hydraulic and electronic options.
SUMMARY OF THE INVENTION
The present invention thus relates to a device for controlling the direction of the trajectory of a wellbore, comprising a shaft driven in rotation, a drill bit secured to the shaft, a substantially cylindrical body coaxial with the shaft and freely rotating in relation to the shaft, one or more pads carried by the body that can move radially, and pad displacement mechanisms. In the device, the displacement mechanisms individually comprise, for each pad, at least one thruster whose longitudinal displacement in relation to the axis of the device causes extension of the pad. The thruster is displaced by an activation system driven by the hydraulic energy supplied by the drilling fluid circulating in the shaft and the actuator comprises a system for selecting the absence of displacement of at least one pad while the others, if any, are displaced.
In particular, the invention can be applied to oil production wells whose position in geologic reservoir beds must be defined relatively precisely. The inclination of the wellbore to the vertical and its azimuth therefore have to be controlled.
The body can comprise means for orientation the body by rotation about the axis of the shaft.
The means for orienting the body can comprise a ballast fastened along a generatrix of the body.
The activation system can comprise an annular piston that moves longitudinally in the body under the effect of the differential pressure between the inner space of the shaft and the inside of the well.
The annular piston can longitudinally displace a cylindrical barrel-shaped part comprising a slot in the direction of a generatrix of the cylinder, the width and the length of the slot corresponding to the shape of at least one thruster of a pad.
The slot can be oriented in relation to the well by adjustment of the body.
The selection system can comprise a series of grooves and at least one finger connected to the body.
The series of grooves can be carried by the barrel the slot of the barrel being oriented in relation to the body by cooperation of the finger and of the series of grooves.
In the device, in the absence of flow of drilling fluid, the series of grooves can be such that the barrel always has the same position in relation to the body.
The invention also relates to a method for controlling the trajectory of a weilbore in which the following stages are carried out:
the device described above is placed at the end of drillpipes,
the drill bit is driven in rotation by rotation of the shaft of the device and a drilling fluid is injected at a flow rate Df,
circulation sequences are carried out between a zero flow rate and a flow rate Da lower than Df, so as to orient the barrel in the body of the device and to actuate at least one pad when the flow rate is Df.
In the present method, the direction of the trajectory can be measured and the orientation of the barrel can be modified if the trajectory is not correct.
The present device fulfils either a centering function or a deviation function, according to its configuration, and it is actuated and controlled mainly by the flow of the drilling fluid. This tool is thus compatible with the equipments and procedures commonly used in drilling.
REFERENCES:
patent: 5060736 (1991-10-01), Neff
patent: 5467832 (1995-11-01), Orban et al.
patent: 5603386 (1997-02-01), Webster
patent: 5836406 (1998-11-01), Schuh
patent: 5931239 (1999-08-01), Schuh
Antonelli Terry Stout & Kraus LLP
Francis du Petrole
Pezzuto Robert E.
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