Patent Application
20080279637
The present invention relates to a complementary locking system for locking legs to the deck of a jack-up offshore drilling platform, as well as methods for installing one such locking system on the legs of an offshore drilling platform.
Offshore drilling platforms, of the jack-up type, for example oil platforms, generally include legs, substantially three in number, supported on the seabed, together with a fitted deck that can be displaced and adjusted in height along the legs and substantially carrying production equipment and living quarters.
After its construction, the platform assembly is generally floated to the drilling or production site, and the legs are lowered into contact with the seabed, then supported on the legs, the deck is hoisted above sea level up to a height that puts it outside the range of the highest waves.
The deck can thus be displaced along the deck's support legs by means of drive mechanisms housed inside a bearing framework supported by the deck and well-known to specialists as a “jack-house”.
Said drive mechanisms of each support leg each comprise at least two opposing geared motor assemblies driving output pinions that cooperate with opposing racks fitted on the legs.
For this, each leg passes through the deck and the bearing framework of said drive mechanisms and is formed of superimposed sections assembled together by welding. Each section generally consists of vertical chords, three or four in number, interconnected by a lattice of metal girders or by caissons.
Each chord is formed, on the one hand, by a rectangular plate and, on the other, by stiffeners each having the form of a half-shell, each welded onto one of the main faces of said plate.
Each rectangular plate comprises teeth on its lateral faces, which form diametrically opposing racks, intended to cooperate with the output pinions of the drive mechanisms.
Throughout the production run, the platform deck is maintained in its operating position out of the water by the drive mechanisms and more particularly by the pinions of said mechanisms, which engage with the teeth of the support leg racks.
Now the deck, due to its structure and due to the fact that it supports all the equipment, represents a load of several thousand metric tons exerted on the various drive mechanisms.
In addition, the legs, which are solidly anchored onto the seabed, are subject to various marine currents which have the effect of producing shear forces on the leg chords. Said forces obviously have repercussions on the various pinions, in addition to the weight of the platform deck.
The purpose of the invention is to provide a complementary locking system for locking legs to the deck of an offshore drilling platform for simply and significantly reducing the load exerted on the drive mechanism pinions of the legs of said platform in its operating position out of the water.
The subject of the invention is therefore a complementary locking system for locking legs to the deck of a jack-up offshore drilling platform, the deck bearing drive mechanisms including, for each leg, at least two groups of opposing pinions, cooperating with the opposing racks and fitted onto the legs for displacing the deck between a floating position and an operating position out of the water and for maintaining this deck on the legs in this operating position, characterized in that it includes, on each leg, at least one assembly comprising two opposing counter-racks, each formed of a plate equipped with teeth intended to be engaged with a rack, and on the same side of the plates, at least one internal element for connecting the internal edges of the counter-rack plates and at least one external element for connecting the external edges of the counter-rack plates.
According to other characteristics of the invention:
The object of the invention is a method of installing a locking system, characterized in that it consists of the following steps:
The object of the invention is also a method of installing a locking system, characterized in that it consists of the following steps:
The object of the invention is equally a method of installing a locking system, characterized in that it consists of the following steps:
The object of the invention is also a method of installing a locking system, characterized in that it consists of the following steps:
The object of the invention is finally a method of installing a locking system, characterized in that it consists of:
The invention will be better understood on reading the description that follows, given by way of example and referring to the attached drawings, in which:
The deck 1 is displaceably fitted onto vertical legs 2 which are each for example triangular in section. These legs 2 may also be square or circular in section. They can be three or four in number, distributed uniformly on the deck 1.
Said deck 1 is fitted displaceably onto the vertical legs 2 intended for being supported on the seabed 3 through the intermediary of a base 4 when the platform is in a drilling or operating position.
In the usual way, each leg 2 is formed of three parallel chords 5 interconnected by a lattice of metal girders 6 or by caissons.
The deck 1 is displaced on the legs 2 by means of drive mechanisms designated as a whole by the reference 20, housed for each leg 2, in a bearing framework 7 also called a “jack-house” by specialists. At the level of each leg 2, each bearing framework 7 is supported by the deck 1, as shown in
As depicted in
In the usual way, the platform is brought to the drilling or production site by floating the deck 1 and the legs 2 are lowered into contact with the seabed 3. Supported on the legs 2, the deck 1 is hoisted through the intermediary of the pinions 22 each rotationally driven by a corresponding geared motor 21 of the drive mechanisms 20, which engage with the teeth 9 of a rack 10.
The deck 1 of the platform is thus raised to the desired height for operation.
In order to reduce the load exerted on the pinions 22 of the drive mechanisms 20, each leg 2 is equipped, at the level of the deck 1, with a complementary locking system for locking said legs 2 to the deck 1.
Referring now to
In general, the complementary locking system is composed of at least an assembly designated by the general reference 30, which comprises two opposing counter-racks 31 each formed of a plate 32 generally rectangular in shape.
The plates 32 allow a space 33 between them for positioning the assembly 30 on the racks 10 of a chord 5 of a leg 2, as will be seen later.
The opposite edges of the two plates 32 are provided with a series of teeth 34 complementary in form to the teeth 9 of the racks 10.
The assembly 30 also comprises, on the same side of the plates 32, at least one internal element 40 for connecting the internal edges 32a of the plates 32 and at least one external element 45 for connecting the external edges 32b of said plates 32.
In preference, the internal element 40 is formed of several parallel stiffeners 41, uniformly distributed over the length of the plates 32 allowing an interval 42 between them. Each stiffener 41 of the internal connecting element 40 has the form of a half-ellipse.
The external connecting element 45 is also formed of several parallel stiffeners 46, uniformly distributed over the length of the plates 32 allowing an interval 47 between them. The stiffeners 46 of the external element 45 are preferably located at the same level as the stiffeners 41 of the internal element 40.
In the examples of embodiment shown in
Finally, the assembly 30 comprises at least one intermediate member for connecting the internal element 40 with the external element 46.
In the examples of embodiment depicted in
First of all, an assembly 30 is placed at the level of the deck 1 and close to the chord 5, arranging the plate 8a of the chord 5 opposite the space 33 left between the plates 32 of the counter-racks 31. Then, the two counter-racks 31 are parted from one another so as to increase the width of the interval 33, as shown in
For this, the system is equipped with means for parting the two plates 32 from one another, which, for this mode of embodiment, consists of at least one source of heating, not shown, applied to at least the stiffeners 41 of the internal element 40. In order to facilitate the parting of the counter-racks 31, the heating source may be applied simultaneously to the stiffeners 41 of the internal element 40 and to the stiffeners 46 of the external element 45. This heating source consists, for example, of a welding torch or electrical heating elements or any other appropriate sources. The form of the stiffeners 41 and 46 is determined for facilitating the parting of the counter-racks 31 from one another during the heating phase whose temperature is of the order of 120° C. In
As soon as said counter-racks 31 are sufficiently parted, as shown in
As shown in
The assemblies 30 thus installed on each chord 5 equipped with racks 10 of each leg 2 of the platform therefore enable the load exerted on the pinions 22 of the drive mechanisms 20 to be significantly reduced.
According to a second mode of embodiment depicted in
In this mode of embodiment, the parts common to the previous mode of embodiment have been designated by the same references and the form of the stiffeners 41 and 46 is identical.
In this mode of embodiment, each stiffener 46 of the external element 45 substantially comprises in the middle of the straight portion 46a, a free space 51 directed towards the internal element 40. Said free space has, for example, the form of a wedge and is intended to receive means of maintaining the plates 32 in the clamped position.
In this mode of embodiment, the system includes means of parting the two plates 32 of the counter-racks 31 from one another at the time of installing the assembly 30 on the racks 10 of a chord 5 of the corresponding leg 2 and of bringing together said two plates 32 after the installation of said assembly 30.
Said means are formed of at least one mechanical device designated as a whole by the reference 55. Several mechanical devices 55 may also be provided.
The mechanical device 55 is composed of a first threaded rod 56 of which one end 56a is screwed into a threaded sleeve 58 and of which a second end 56b is hinge-mounted onto a base plate 59 fixed, for example by welding, onto the stiffeners 46. The mechanical device 55 also includes a second threaded rod 57 of which a first end 57a is screwed into the threaded sleeve 58 and of which a second end 57b is hinge-mounted onto a base plate 59 fixed, for example by welding, onto the stiffeners 46.
The sleeve 55 and the threaded rods 56 and 57 extend parallel to the plates 32 of the counter-racks 31.
The assembly 30 as depicted in
First of all, at least one assembly 30 is placed at the level of the deck 1 and close to a chord 5 of a leg 2. Then, the sleeve 58 is rotated in a determined direction to cause the screwing of the threaded rods 56 and 57 into the sleeve 58 which, via the intermediary of the stiffeners 46 becoming deformed, causes an increase in the width of the space 33 left between the teeth 34 of the counter-racks 31, as shown in
The two counter-racks 31 are fitted onto the racks 10 of the chord 5 in such a way that the teeth 34 of said counter-racks engage with the teeth 9 of the racks 10. The sleeve 58 is rotated in the reverse direction thus causing the translation of the threaded rods 56 and 57 in the opposite direction, i.e. in a direction causing a reduction in the width of the space 33 and, accordingly, clamping of the counter-racks 31 onto the racks 10 of the chord 5.
To maintain the assembly 30 in this clamping position, at least one wedge-shaped wedge 52 is inserted into the housing 51 arranged in the stiffeners 46, as shown in
Other mechanical devices 55 may be provided for parting the counter-racks 31, for example one or more hydraulic or pneumatic jacks or any other appropriate system.
Furthermore, the mechanical device 55 may be composed, as depicted in
In this mode of embodiment, the initial parting between the teeth 34 of the counter-racks 31 is designed to be able to place the assembly 30 on the teeth 9 of the racks 10 without having to part said counter-racks 31 from one another, as in the preceding modes of embodiment.
Thus, after the assembly 30 has been placed on the racks 10 of a chord 5, the metal rod 60 is heated by appropriate means which, by expansion of said rod 60, causes the counter-racks 31 to be brought together and said counter-racks 31 to be clamped onto the racks 10 of the chord 5. The assembly 30 is maintained in this clamping position by the insertion of at least one wedge-shaped wedge 52 into the housing 51 arranged in the stiffeners 46, as shown in
In this mode of embodiment, the parts common to the previous modes of embodiment have been designated by the same references.
In this case, the external connecting element 45 is also composed of stiffeners 65 allowing an interval 66 between them.
Each stiffener 65 of the external connecting element 45 is formed of a straight central portion 65a extending parallel to the plates 32 of the counter-racks 31 and two lateral portions 65b each connecting one end of the central portion 65a to an external edge 32b of a plate 32.
Each spacer 50 extends between a stiffener 41 of the internal connecting element 40 and the corner formed between the straight portions 65a and 65b.
In this case also, the form of the stiffeners 41 and 65 contributes to exerting a parting force of the counter-racks 31 with respect to one another during the heating of at least the stiffeners 41 of the internal connecting element 40.
The mechanical devices for parting the counter-racks 31 may also be fitted on the stiffeners 65 in this mode of embodiment.
According to a fifth mode of embodiment depicted in
Said horizontal plates 70 contribute to the diffusion of heat towards the stiffeners 46 of the external element 45 during heating of the stiffeners 41 of the internal element 40.
Moreover, in addition to the stiffeners 41 and 46, said horizontal plates 70 enable the hold of the assembly 30 onto the racks 10 to be improved. This is because the weight of the platform deck 1 creates what is termed by specialists a cogging thrust, which has a tendency to part the counter-racks 31 from the racks 10. This phenomenon is limited by the horizontal plates 70.
The assembly 30 of each mode of embodiment previously disclosed, may each be associated with the aforementioned means of parting and may or may not be equipped with horizontal plates 70. The stiffeners 46 may or may not be provided with a housing 51 for the positioning of at least one wedge 52 and may be formed of a central portion 46a and two curved portions 46b or only of straight portions 65a and 65b.
The various parts making up the assembly 30 are interconnected for example by welding or by any other appropriate means.
Without going outside the scope of the invention, several assemblies 30 may be fitted one above the other onto a rack 10 of a chord 5 of a leg 2.
In all cases, the assembly or assemblies 30 are, after fitting onto a rack 10, wedged with respect to the deck 1 in such a way that the assemblies 30 partly support the deck 1 so as to relieve the pinions 22 of the drive mechanisms 20.
Referring now to
In general, the complementary locking system is composed of at least an assembly designated by the general reference 30, which comprises two opposing plates 31 each forming a counter-rack and being generally rectangular in shape.
The counter-rack 31 plates allow a space 33 between them for positioning the assembly 30 on the racks 10 of a chord 5 of a leg 2, as will be seen later. The opposite edges of the two counter-rack 31 plates are provided with a series of teeth 34 complementary in form to the teeth 9 of the racks 10.
Each counter-rack 31 plate is borne by at least one support plate designated by the general reference 35.
In the example of embodiment depicted in
The assembly 30 also comprises, on the same side of the support plates 35, at least one internal element 40 for connecting the internal edges 36a of the plates 35 and at least one external element 45 for connecting the external edges 36b of said plates 35.
In preference, the internal element 40 is formed of several parallel stiffeners 41, distributed over the length of the counter-rack 31 plates allowing an interval 42 between them. Each stiffener 41 of the internal connecting element 40 has a curvilinear form, e.g. the form of a half-ellipse.
The external connecting element 45 is also formed of several parallel stiffeners 46, distributed over the length of the counter-rack 31 plates allowing an interval 47 between them. The stiffeners 46 of the external element 45 are preferably located at the same level as the stiffeners 41 of the internal element 40.
In the example of embodiment depicted in
Each stiffener 46 of the external element 45 includes a central portion 46a that may be straight and two lateral portions 46b extending a portion 46a up to an external edge 36b of a support sub-plate 35a of a support plate 35.
The assembly 30 also comprises at least one intermediate member for connecting the internal element 40 with the external element 45 and which, in the example of embodiment depicted in
According to the invention, at least one counter-rack 31 plate is movable on its corresponding support plate 35 by at least one means of displacement 60 between an open position for installing the assembly 30 onto the racks 10 of the leg 2 and a closed position for locking the counter-rack 31 plates onto the racks 10 of said leg 2 after the installation of said assembly 30. Referring now to
As shown in
In the example of embodiment depicted in the figures and more particularly in
On the other hand, no clearance J other than the functional clearance is allowed between the cam 62 and the orifice 63 of the means of displacement 60 situated the lowest on the movable counter-rack 31 plate.
Other distributions of the clearance J between the cam 62 and the orifice 63 of the various means of displacement 60 may be envisaged according to the displacement of the movable counter-rack 31 plate that is wanted for its clamping.
In general, some means of displacement 60 have a greater clearance J than others.
The means of displacement 60 not having any clearance, other than the functional clearance, and called main means of displacement, are driven first while the means of displacement 60 having a predetermined clearance in addition to the functional clearance and called secondary means of displacement are driven after said main means of displacement so as to obtain a lateral displacement of the movable counter-rack 31 plate during the clamping of said main means of displacement.
As shown in
In addition, the cam 62 of each means of displacement 60 comprises one end 66 jutting out with respect to the counter-rack 31 plate and intended to cooperate with a member for rotationally driving said cam 62.
By way of example and as shown in
Finally, the cam 62 of each drive means 60 is provided with a shoulder 67 resting on the movable counter-rack 31 plate so as to maintain said counter-rack 31 plate on the support sub-plates 35a of the corresponding support plate 35.
The assembly 30 includes at least one means of locking the movable counter-rack 31 plate on its support plate 35 in the closed position for locking the counter-rack 31 plates onto the racks 10 of the corresponding leg 2.
The assembly 30 comprises as many means of locking the movable counter-rack 31 plate as means of displacement 60 of this movable counter-rack 31 plate.
As is apparent from
The ring 74 is provided with a dowel 75 intended to be inserted into one orifice 76 of a series of orifices 76 arranged in the movable counter-rack 31 plate (
The fitting of the assembly 30 as depicted in
First of all, at least one assembly 30 is placed at the level of the deck 1 and close to a chord 5 of a leg 2.
The movable counter-rack 31 plate is in an open position so that the width of the space 33 allows placing the teeth 34 of the counter-rack 31 plates onto the teeth 9 of the chord 5 of the corresponding leg 2.
Then, the two counter-rack 31 plates of an assembly 30 are fitted onto the racks 10 of the chord 5 in such a way that the teeth 34 of said counter-rack 31 plates engage with the teeth 9 of the racks 10. After the installation of said assembly 30, a device is fitted on the drive head 66 of the cam 62 of one of the main means of displacement 60 for rotationally driving said head 66 to rotate the corresponding cam 62 in order to displace the movable counter-rack 31 plate. Then, the same operation is carried out on the other said main means of displacement 60 in order to laterally displace said movable counter-rack 31 plate. According to another method, the cams 62 of the main means of displacement 60 may be driven simultaneously.
In the case of two main means of displacement 60 and two secondary means of displacement 60, one of the main means of displacement 60 comprises, between the cam 62 and the orifice 63, a larger clearance than the clearance between the cam 62 and the orifice 63 of the other main means of displacement 60, but smaller than the clearance of the secondary means of displacement 60.
Generally speaking, the secondary means of displacement 60 always have a larger clearance than the largest clearance of the main means of displacement 60.
Subsequently, the cams 62 of the secondary means of displacement 60 are rotationally driven for completing the clamping of the two counter-rack 31 plates onto the racks 10 of the chord 5 of the corresponding leg 2.
If necessary, after said clamping has been carried out, another complementary clamping is performed by rotationally driving the cams 62 of the main and/or secondary means of displacement 60.
During the rotation of each cam 62, the ring 74 of each means of displacement 60 is rotationally driven via the intermediary of the cogs 71 and 72 arranged respectively on the shoulder 67 of the cam 62 and in the orifice 73 of said ring 74. Each ring 74 is locked onto the movable counter-rack plate in the closed locking position of said movable counter-rack 31 plate by placing a dowel 75 in an orifice 76, as shown in
Maintaining the movable counter-rack 31 plate in its closed position is completed by screwing members 80 which pass through said counter-rack 31 plate and which are screwed into the support sub-plates 35a of the support plate 35. Next, each assembly is wedged by appropriate means, not shown, on the platform deck 1.
In the case where the movable counter-rack 31 plate comprises a single means of displacement 60, it is sufficient to rotationally drive the cam 62 of said means of displacement to bring the corresponding counter-rack 31 plates into a clamping position.
The horizontal plates 49 arranged between each pair of stiffeners 41 and 46, in addition to said stiffeners 41 and 46, enable the hold of the assembly 30 onto the racks 10 to be improved. This is because the weight of the platform deck 1 creates what is termed by specialists a cogging thrust, which has a tendency to part the counter-rack 31 plates from the racks 10. This phenomenon is limited by the horizontal plates 49.
Without going outside the scope of the invention, several assemblies 30 may be fitted one above the other onto a rack 10 of a chord 5 of a leg 2. In all cases, the assembly or assemblies 30 are, after fitting onto a rack 10, wedged with respect to the deck 1 in such a way that the assemblies 30 partly support the deck 1 so as to relieve the pinions 22 of the drive mechanisms 20.
According to a variant, the two counter-rack plates may be movable.
| Number | Date | Country | Kind |
|---|---|---|---|
| 0501157 | Feb 2005 | FR | national |
| 0509230 | Sep 2005 | FR | national |
| Filing Document | Filing Date | Country | Kind | 371c Date |
|---|---|---|---|---|
| PCT/FR2006/000224 | 2/1/2006 | WO | 00 | 4/18/2008 |
