Patent Application
20120043133
1. Field of the Invention
The present invention concerns the radial displacements of at least two mechanical parts adjacent to one another, in particular for steerable drilling applications. It concerns in particular drilling which requires accurate trajectory control, in particular in the fields of the petroleum and gas industry, civil engineering, geothermics and more generally in all fields of trenchless underground operations, or even the accurate steering of mechanical parts, such as rolling mill rollers, in particular.
The invention concerns more particularly, whatever the application envisaged, an annular device providing for controlled essentially radial displacements and/or stresses between at least two mechanical parts with a common axis in one or two directions.
2. Description of the Prior Art
Drilling tool steering devices have been described for example in documents WO 90/07625, U.S. Pat. Nos. 6,581,699 and 2,898,935.
These devices meet certain objectives but they do not always make it possible to achieve the best results in all circumstances.
It is generally proposed to use hydraulic radial or tangential jacks, which equates to a simple, reliable and reversible design. But such jacks generally operate at high pressure and offer short travel in such an environment. Furthermore, they are difficult to instrument in order to obtain accurate position control.
Document U.S. Pat. No. 3,677,354 recommends the use of inflatable cushions for displacement in a plane in two directions in a very restrictive annular environment. These offer a high load and expansion capacity with low operating pressures, but they are fragile, especially at high temperature, and lack rigidity.
Document U.S. Pat. No. 5,875,859 suggests using double eccentric systems, which are capable of generating very great stresses and managing a multitude of positions with great accuracy. But the design of these systems makes them generally irreversible and it is essentially proposed that they be associated with needle bearings. Their drive necessitates complex control systems and it generally necessitates two clutches or two independent motor drives.
Also, wedge systems have been proposed, also capable of generating high stresses, but the implementation of which is extremely delicate in an annular space and which are by nature better suited to a unidirectional mode.
It is universally accepted that the reliability of a system is more often inversely proportionate to its complexity, which is itself also an important cost factor, both for manufacture and for maintenance.
According to the present invention, an alternative reversible or irreversible solution has now been developed, radially compact and controllable with accuracy with respect to both stress and position, and also perfectly suitable for drilling, therefore able to operate in the presence of shocks and vibrations, on the basis of research aimed at responding to the above mentioned expectations—in particular those aroused by the attractive nature of the device described in patent FR 2.898.935.
The present invention is based on the development and preparation of an advantageously bidirectional system for generating essentially radial stress and/or displacements with respect to the X-X axis of the annular system which is described in more detail below.
The first object of the invention is thus a device for generating essentially radial displacements of interconnected mechanical parts, in particular for steerable drilling, said device being designed and constructed to provide for essentially radial displacements of at least one mechanical part with respect to its X-X axis common with that of at least one other mechanical part functionally connected to the first one, said device comprising, in order to provide for such respective displacements of said at least two respective mechanical parts (in particular a shaft or housing which is steerable with respect to a frame in a drilling tool):
(I) two swivelling rings and a frame producing two nested ball joint connections (a) and (b), with respective centres A and B, eccentric by a distance or value ε along said X-X axis common to the two ball joint connections in a position said to be neutral,
(II) one or more actuators integrated with said frame in a barrel arrangement about the X-X axis for driving the mechanism, each actuator being connected to the swivelling ring with centre A by a push rod, also called a compression rod, and
(III) a guide ring integrated with said frame for guiding the push rods via a bidirectional planar link (e),
and also, optionally, functional elements able to provide for start-up, drive and maintenance of correct operation of said device, which is thus annular and isostatic.
Another subject of the invention is equipment integrating a device as described here, in particular drilling equipment intended for applications necessitating accurate trajectory control, for example (but non-limitatively) in the fields of the petroleum and gas industry, civil engineering, geothetmics and more generally in all fields of trenchless underground operations, among others.
In such equipment, the device is in a unidirectional version so as to make it possible to constitute a steerable bent housing connection, while it is in a bidirectional version to constitute a drilling tool steering system in turning/rotary mode (known as RSS or “Rotary Steerable System”), arranged to operate dynamically and autonomously or interactively at the bottom of a shaft in both cases.
According to the invention, a bilateral system is thus created for generating essentially radial displacements with respect to such an X-X axis in one or two directions from two nested ball joint connections with respective centres A and B, eccentric by a value ε along said X-X axis common to the two ball joint connections when they are in a position said to be “neutral”, and for driving the thus-produced mechanism by means of one or more actuators in a barrel arrangement about the above mentioned X-X axis. In such a system, each actuator activates—independently and in a given direction—the ball joint connection (a) via a push rod guided in a plane defined by the X-X axis and said direction.
In the case of a unidirectional system, the system is driven by at least 1 actuator (unilateral system) or two actuators (bilateral system) in a barrel arrangement about the X-X axis at 180° to one another.
In the case of a bidirectional system, the system is driven by two actuators (unilateral system) in a barrel arrangement about the X-X axis at 90° or by N actuators (bilateral system) in a barrel arrangement about the X-X axis and distributed in this case regularly every 360°/N, the minimum number of actuators then being 3.
In advantageous embodiments, one and/or more of the following arrangements are optionally implemented, separately or in combination, if technically possible:
The invention will be better understood and other objects, advantages and characteristics of it will appear more clearly in the light of the following detailed description of preferred embodiments, which is provided for illustration and is in no way restrictive, while drawings are attached to said description in which:
With reference to the drawings thus succinctly described, in particular to
In the bilateral device according to the invention, as defined above, the nested rings 11 and 13 are displaced under the action of the push rods 3 pushed by actuators 2 and/or 2′, and guided by a guide ring 4. Said nested rings are rotatable in their respective housings (a12) and (b11). It should be stated here that the housing for the ball joint 13 is included in the steerable swivelling ring 11; in other words, the convex surface of the ball joint connection (a) and the concave surface of the ball joint connection (b) form part of the same component of the device, namely the steerable ball joint 11.
In one aspect, the device according to the invention essentially comprises:
Thus, referring to
The translations in the opposite direction of pistons 21 and 21′ by a value τ under the action of a pressure P introduced by the duct 23 bring about the rotation of the swivelling ring 11 about point A by a value α and the radial displacement Δ of centre B of the internal ring 13 and thus of the shaft 5.
When the hydraulic pressure P is released, the return springs 22a and 22b′ respectively return the pistons 21 and 21′ to their median position and, consequently, the swivelling ring 11 to its “neutral” position.
According to an advantageous characteristic of the invention, the jacks 2 are single-acting jacks, which makes it possible to simplify their construction and control. They are in practice fed by hydraulic means known to a person skilled in the art and advantageously fitted with a pressure relief valve, in order to avoid overloads in the set of parts making up the mechanism, and a solenoid valve. The selection of the type of solenoid valve depends in particular on the types of operation required in normal and/or degraded modes or, in other words, on the configuration required for the control system for the device and/or in the event of failure of the power supply or drive device, in order to obtain the best safety and/or the lowest possible consumption. For example, each hydraulic jack of an actuator 2 may be driven by a naturally closed solenoid valve such that the system is always locked or by a naturally open solenoid valve such that the system returns to “neutral” position in the event of an incident.
There may also optionally be a proportional gate valve for the force control system for the jacks, essentially in the case of a hydraulic actuator.
According to an equally advantageous characteristic of the invention, the jacks 2 are preferably electromechanical, such that the steering of the ring 11 can be carried out accurately and irreversibly.
According to another advantageous characteristic of the invention, the steerable ring 11 and the internal ring or ball joint 13 are made from bronze, including beryllium copper, or type 100 C 6 or 100 CD 7 bearing steel to maximize its radial capacity, or non-magnetic stainless steel, in particular for an application in the field of steerable drilling.
The surfaces of the ball joint connections (a) and (b) are advantageously subjected to surface treatment to reduce the friction coefficient and thus maximize the performance and the service life of the contacts.
According to yet another advantageous characteristic of the invention, the push rods are made from materials with a high modulus of elasticity and elastic limit in order to be able to transmit large stresses in a restricted radial space with no risk of bending and flaking of the surfaces of the connections (c) and (d).
The eccentration value ε of the two ball joints is between 0.005 and 0.50 times the diameter of the spherical surface (a), and the tilting value is between 0 and 45°. Thus, the device according to the invention presents a small radial size, without, however, any reduction in its capacity to transmit force and radial displacement. It is also of a simple and robust construction, in particular owing to the ability to operate under reduced pressure by playing on the eccentration value, which makes it possible to envisage a particularly broad range of applications, including, and this is an undeniable benefit, in the presence of shocks and vibrations.
Another particular feature of the device according to the invention is its ability to be irreversible or reversible.
When it is desirable that the system has positive safety and returns to its position known as “neutral” (centres of both ball joints aligned on the X-X axis) naturally, the system is then reversible by association with a return system, for example with spring(s), or reversible actuators, advantageously hydraulic or electro-hydraulic and driven by at least one normally open solenoid valve. The return system may comprise one or more springs integrated into each actuator or the flexible shaft (see documents WO 90/07625, U.S. Pat. No. 6,581,699 and FR 2.898.935), or one or more springs acting directly on the swivelling ring 11.
Such a return system is arranged and controlled as a function of the eccentration value ε, the performance of the two ball joint connections (a) and (b), the reversibility of the actuators 2, and the rigidity of the shaft 5 (or the part referenced 7 in the case illustrated in
When it is desirable that the system is irreversible, namely that it remains in position in the event of malfunction of the associated drive system, the actuators are preferably also irreversible, advantageously electromechanical.
Yet another particular feature of the device according to the invention is the fact that the recommended means provide for the transmission of the stress from each actuator 2 to the swivelling or steerable ring 11 through push rods 3 presenting:
This fundamental provision guarantees the isostatism of the system, prevents the angular jamming of the swivelling and steerable ring 11 with respect to the actuators 2 and makes it possible appropriately to maximize or minimize the number of actuators and also the lever arm by arranging the push rods over a respectively maximum or minimum diameter in order to optimize the stresses of the actuators and the rate of displacement.
Thus, the radial size of the device can be reduced as much as possible without compromising its force, displacement, accuracy and reversibility or irreversibility capacities, by adapting the eccentration value ε of the centres A and B of the ball joint connections respectively (a) and (b), the performance of said ball joint connections, the number, diameter of distribution and angle of inclination of the push rods 3, and also the number, type, force and accuracy of the actuators 2 to the requirements of the application envisaged, hence a potentially wide range of applications.
In the construction known as double/tandem (see
One of the benefits of the invention is its simple and robust construction, making use of principally surface contacts, mechanically very capacitive, with regard both to radial load and in the event of shocks and/or vibrations, in comparison with the point connections on balls or linear connections on needles. Also, such a system according to the invention produces maximum damping capacity.
In absolute terms, the above mentioned surface contacts are accompanied by one or more point contacts (c), but this may be replaced, if so desired, by swivelling pads of a type known to a person skilled in the art.
The device according to the present invention is thus simple and radially compact and resistant to shocks, temperature and vibrations. It is thus generally perfectly adapted for the constraints currently encountered and taken into account in design imposed by various factors and more particularly for drilling tool steering systems as described in the above mentioned documents WO 90/07625, U.S. Pat. No. 6,581,699 and FR 2.898.935.
Although the invention has been described above principally with reference to drilling, a person skilled in the art will understand that it can have multiple other applications, for example in all fields where accurate steering is required for mechanical parts and/or under high loads, such as rolling mill rollers, among other things.
| Number | Date | Country | Kind |
|---|---|---|---|
| 1003406 | Aug 2010 | FR | national |
