JPH0686235B2 - Anchor connector with rotating ear - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to offshore oil production, and in particular to connectors for tethers in tension leg platform (TLP).

BACKGROUND OF THE INVENTION Offshore oil drilling and production has become an important industry globally. Many technologies have been developed to achieve what was initially impossible, namely the drilling and production of oil reserves from under the sea floor to above sea level platforms.

One of the key designs that has had great success in the production of offshore oil is the tension leg platform (TLP). In this design, the platform is effectively anchored to the seabed via multiple tethers that extend vertically from the seabed to the platform floating above the sea surface. These tethers are kept in tension by the buoyancy of the platform. Tidal current and wave effects are compensated by the lateral movement of the platform and tether. Vertical movements normally associated with sea pitching, pitching and rolling are eliminated by the combined buoyancy of the platform and tether. Generally, the rating structure is permanently installed on the seabed to receive the tether along with some mechanism to absorb the pivoting movement of the tether. The platform is then placed in place with the tethers latched to the subsea structure. Platforms can be left in place for many years during drilling and production, but are expected to eventually be delatched from subsea-mounted latching structures for reuse or scraping elsewhere. To be done.

Several designs have been proposed for the latching mechanism that secures the tether to the subsea receptacle mechanism. One is 1985
It is disclosed in U.S. Pat. No. 4,498,814, which was patented on Feb. 12, 2012 and assigned to Vizkers. This design has a collet configuration with shoulder blocks that are deployed to contact the mooring sleeves at the bottom of the sea. A flexible joint allows the tether to rotate or twist. However, this design requires hydraulic actuation of the tether de-latch. Hydraulic actuation necessarily requires a pressurized hydraulic line that extends from the connector at the seabed to the sea level where the hydraulic pump and control circuitry is located. The hydraulic line is typically routed through the hollow interior of the tether. If some parts inside the tether are designed to dry to increase buoyancy,
Considerable effort is required to seal the hydraulic tubing in the bottom partition perforated area at the bottom of the tether. If the test instruments run inside the tether, they can foul and damage the hydraulic lines that reach the connector. The dependence on hydraulic action creates problems with regard to the reliability of connector disconnection over the long service life required for this type of system. Any of the seals used can easily degrade and break for periods as long as 30 years. Since the operating components of the connector are inside the latch body and hidden from outside observation,
Visual inspection makes it virtually impossible to analyze or confirm any mechanical or hydraulic problems.

Another design for a TLP connector is disclosed in U.S. Pat. No. 4,390,555, which was patented March 27, 1984 and is literally assigned to Becto Offshore. The design of this patent relies on a series of ratcheted dogs with shoulder blocks.
These latch dogs are attached to the lower end of the tether and are retained in the retracted position when the lower end of the tether is plugged into the void of the subsea mounting structure. Each of the dogs is pivotally attached to the tether. As the tether is plugged into the subsea structure, the traveling tool releases the dog and pivots it against the receptacle load to secure the tether. To disengage the tether, the dissociation tool travels down the hole in the tether to retract the dog. This design is incompatible with tethers that have a dry interior. This is because the disengagement tool must run from the sea surface through the tether to the connector. Also in this case, visual inspection and confirmation of the latch are difficult.

In addition to the further complication of the connector, the industry needs the existence of an auxiliary latch dissociation technique even if the main latch dissociation technique fails.

SUMMARY OF THE INVENTION According to one aspect of the present invention, an anchor connector is provided for releasably securing a tether of a tension leg platform to the seabed. The anchor includes a first member fixed to the seabed and a second member fixed to the lower end of the tether. A ring with a central vertical axis is installed. The ring is then at least one, preferably at least three, extending horizontally along a radius about the vertical axis.
Has individual ears. A cylindrical receptacle is provided, also having a central vertical axis. Receptacle is the main guide,
It has vertical slots, auxiliary guides and notches. The ring is attached to one of the members, while the cylindrical receptacle is attached to the other one of the members. The ring and receptacle are mounted on the member to allow relative rotation between the ring and the receptacle about the central axis of the tether.

In operation, the tether is lowered vertically until the ears make contact with the main guide. Due to the continued descent of the tether,
The main guide rolls the ear into the interior along the vertical slot and brings it into contact with the auxiliary engagement guide. As the tether further descends, the supplemental engagement guides rotate the ears approximately midway to the notch. The subsequent upward movement of the tether causes the ear to rotate the remaining distance to the notch and engage the notch to secure the tether to the seabed. During this operation, the tether is moved only vertically and is therefore not required to rotate or pivot about its central axis. The movement required to guide the ear into the notch is completely replaced by the rotation of the ring and the ear.

To disengage the tether from the seabed, the tether is lowered again to engage the ear with the dissociation guide. As the tether descends further, the dissociation guide rotates the ear approximately midway to the second vertical slot. The raising motion of the tether rotates the ear for the remaining distance and pulls the ear past the second vertical slot and disengages the first member from the second member.

According to another aspect of the invention, the ring is mounted on the second member for rotation about a vertical axis, and
One or two ears, preferably at least three ears, are evenly spaced from each other along their circumference. An elastomeric element is coupled between the ring and the second member to allow pivotal movement of the tether about a center of rotation that lies on the vertical axis of rotation of the tether. Cylindrical receptacle is first
Has a main guide sufficient to secure the tether to the seabed with all ears engaged in the notch, a vertical slot, and an auxiliary guide.

According to another aspect of the invention, the ear may be attached to the first member at the seabed. The guide, slot and retaining notch may be attached to the second member at the lower end of the tether.
In this configuration, one or both members may be fitted with a rotating structure that allows the ears to disengage from the retaining notches.

If desired, multiple rows of ears that interact with multiple rows of notches may be provided. Furthermore, the sequence of attachment of the elastomeric element, the ear and the notch between the tether and the seabed can be modified according to requirements to suit a particular application.

In the event of contamination that impedes the free rotation of the ring and ears with respect to its adjacent members, it may be necessary to move the tether vertically to rotate the entire tether and disconnect the tether and latch assembly from the subsea mounting receptacle assembly. It can be dissociated by allowing. It provides a reliable auxiliary dissociation mechanism that meets the industry requirements.

BRIEF DESCRIPTION OF THE DRAWINGS For a more complete understanding of the present invention and its advantages, reference is now made to the following description taken in conjunction with the accompanying drawings. In the accompanying drawings: FIG. 1 is a perspective view of a rotary ear anchor connector that constitutes a first embodiment of the present invention.

2 is a vertical cross-sectional view of the latch assembly used in the connector of FIG.

FIG. 3 is a top view of the receptacle assembly of FIG.

FIG. 4 is a development view of the internal structure of the receptacle assembly.

DETAILED DESCRIPTION Referring to FIG. 1, a rotating eared anchor connector 10 for securing a tether 12 of a tension leg platform (TLP) 14 to the seabed is illustrated. Connector is tether 12
The anchor latch assembly 18 forming the lower end of the
And a receptacle assembly 20 permanently installed thereon.

Referring to FIG. 2, further details of the latch assembly 18 are described. The latch assembly 18 may be used with any tether structure that allows vertical up and down movement of the assembly.
However, the illustrated tether 12 has a tubular shape with a hollow dry interior configured such that when installed, the tether produces a near neutral buoyancy. For example, the tether has a major diameter substantially along its entire length of 101.0 cm (40 in). Preferably, the tether is reduced in diameter at the portion 22 to which the assembly is secured (first
See figure). The reduced diameter at the portion 22 increases the flexibility of the portion 22, which allows the tether to
When pivoting relative to 10 and the seabed 16, the tether portion 22
This is because the stress generated in the is reduced. For example, the part
22 can be reduced from the main portion diameter of the tether to a final diameter of 43.0 cm (27 in). However, such diameter reductions or alternative designs are generally determined by the overall system design and not by the operation of the present invention.

A central shaft 24 is attached to the portion 22. Shaft
The lower end of 24 terminates in a hemispherical concave surface 26 of radius R1 centered at point 28 on vertical symmetry axis 30 of tether 12 and latch assembly 18. The surface 26 is partly formed by a flange 32, which forms on its outer surface a hemisphere 34 of radius R2, which is likewise centered on the point 28.

The elastomer assembly 36 has a flange 32 on its inner surface 38.
Is adhered to the hemisphere surface 34 of. The elastomer assembly is
Preferably, it is an assembly of multiple elastomeric elements 40 of elastomeric material shaped into a hemispherical portion centered at 28. If desired, a rigid reinforcing element 42, a hemispherical portion centered at point 28, may be glued between the elements to reinforce elastomer assembly 36. point
A collar 44 having a hemispherical inner surface 46 centered at 28 is glued to the outer surface 48 of the elastomeric assembly 36.

A rotating ring 50 is fitted around the flange 32 and collar as shown. The ring 50 is a centering ball 52 having a convex hemisphere 54 with a radius of approximately R1 centered at a point 28, which abuts the concave surface 26 of the central shaft 24 and pivots between elements about the point 28. It has a centering ball for guiding the dynamic movement. The collar 44 engages the shoulder 56 of the ring 50 to retain the ring on the collar 44, but allows the ring 50 to rotate about the axis of symmetry 30 relative to the flange 32 and the tether 12. Three radial ears 58 extending perpendicular to the axis 30 project radially outward from the outer surface 60 of the ring. As can be seen most clearly in FIG. 1, the ears have a diamond shape with upper slopes 62,64 and lower slopes 66,68. The ears are evenly spaced from each other along the circumference of the outer surface 60 in a particular orientation, which translates to a 120 degree separation between one ear and adjacent ears for three ears. To be

Details of the receptacle assembly 20 will now be described with reference to FIGS. 1, 3 and 4. The assembly 20 includes a cylinder 70 that is immovably and permanently installed on the seabed 16. This installation is done by any satisfactory technique. Three members 74, 76, 78 are attached to the inner surface 72 of the cylinder 70. Each member forms an inclined main guide surface 80, 82, sidewalls 84, 86, lower bevels 88, 90, and a notch 92 therein. Member 74,
Underneath 76 and 78 are spaced apart annular rings 94 forming a series of auxiliary guide surfaces 96, which are composed of alternating auxiliary engagement guide surfaces 98 and auxiliary disengagement guide surfaces 100.
Each of the guide surfaces 96 is provided with a stop surface 102 for stopping the rotation of the ear 58 at a proper interval.

The operation of the connector will be described with particular reference to FIG.
The tether and anchor latch assembly 18 is lowered near the receptacle assembly 20. At some point, the ears 58 enter the openings in the cylinder 70 and into close proximity to the main guide surfaces 80,82. The guide surface 80 of one member and the guide surface 82 of an adjacent guide member cooperate to rotate the ring 50 and an ear contacting one of the faces is defined by a vertical edge defined between the side walls 84 and 86 of each adjacent member. It may be appreciated that it will be introduced into slot 104.

Each of the three or more ears 58 is generally at the same time
Contact one of 80 or 82. The ear then slides down along the surface and ring 50 rotates about axis 30 to align the ear with vertical slot 104. To facilitate this movement, the shoulder 56 rotates relative to the collar 44, thus the tether does not need to rotate about its axis 30 to engage the connector.

As the tether continues its descending movement, the lower sloped surface 68 of each ear at the bottom of each vertical slot 104 has an auxiliary engagement guide surface 9
Engage with 8. Due to the continued downward movement, the ring 5
0 is rotated about axis 30 relative to the tether until the ears abut stop surface 102. In this respect,
The tether cannot descend any further. At sea level, stopping the descent of the tether provides a signal to lift the tether to perform the final process of engaging the latch assembly within the receptacle assembly. As the tether is lifted, the upper beveled surface 64 of each ear engages the surface 901 of the member and rotates the ring sufficiently about axis 30 to align each ear with notch 92, thereby notching each ear. Secure in and complete the bond. The pulling force on the tether caused by the buoyancy of the platform secures the ear within the notch 92.

Once coupled, the wave and tidal current effects on the platform are absorbed by the pivoting motion of the tether about pivot point 28, which is enabled by the deflection of elastomer assembly 36. In a typical application, multiple tethers and connectors will be used on each platform.

When it is necessary to separate the tether 12 from the assembly 20 for inspection, maintenance or removal of the platform from the base, the tether 12 is lowered so that each ear contacts the auxiliary dissociation guide surface 100. To be exercised. Further downward tether movement causes the ears to be slid downward along surface 100 and ring 50 again relative to the tether about axis 30 until ear movement is stopped by stop surface 102. And then rotate. The center of motion is again detected at sea level and provides a signal to start lifting the tether.

As the tether is lifted, the surface 64 of the ear 58 will
The ring 50 is rotated in contact with the faces 88 of 4,76,78 and the ears are allowed to rise through the vertical slot 104 to separate the anchor latch assembly 18 from the receptacle assembly 20.

If a remotely operated submersible (ROV) is used, the tether and receptacle assembly features various axial and circumferential markings visible by the ROV to monitor ratcheting and unlatching. Can be attached. For example, proper insertion of the tether into the receptacle assembly is accomplished by providing the tether and receptacle assembly with axial marks that align with the proper insertion of the tether.
Can be assisted and confirmed by ROV. The ROV also assists and confirms the relative axial movement of the ring 50 and the receptacle assembly to various axial points of action by the alignment of circumferential markings located on the tether and receptacle assembly. Can be used.

One significant advantage of the present invention over the prior art is that it can provide a reliable auxiliary dissociation mechanism. As mentioned previously, in normal operation the tether 12 does not need to be rotated about its vertical axis in its ratching and unlatching. The rotation required to engage the ears 58 with the notches 92 and subsequently disengage these ears is replaced by rotation of the ring 50 relative to the tether. However, if normal operation of the connector is not possible due to corrosion, damage or other factors,
By rotating the tether 12 about its vertical axis 30 and preparing the ear for release from the notch, the ear can be moved relative to the members 74,76,78.

Although three ears 58 and cooperating notches 92 are illustrated in the drawings and described above, the advantages of the present invention are that they use a greater or lesser number of cooperating ears and notches. It will be clear that this can be achieved.

Although the ears are shown as having a diamond shape, guide surfaces and any other shape that cooperates with the notches may also be used. For example, the ear may have a rounded contour. It is preferred to similarly shape the notch and ear notch engaging surfaces to evenly distribute the force transmitted between the ear and the notch as evenly as possible.

In addition, the ear was described as being elastically attached to the lower end of the tether. But the ears are cylinders on the seabed
It may be permanently mounted within 70 or other structure and members 74,76,78 are resiliently coupled at the lower end of the tether to cooperate with the ear in substantially the same manner. In such an arrangement, the ears or members 74,76,78
May be mounted for rotation about axis 30.
In practice, the ears and members 74,76,78 may all be mounted for rotation about axis 30. If desired, the elastomeric assembly forms part of a permanent undersea fixture and may be optionally coupled to an associated member or ear.

In the figures and the above description, only one row of ears and notches was used. However, it may be desirable to use multiple rows of ears and notches to provide greater force transmission capacity. In such a configuration, the cylinder
70 may be height-extended to mount multiple rows of members 74,76,78 stacked in vertical rows but forming a common vertical slot. The ring may be fitted with multiple rows of ears, where each ear is located in one row stacked vertically above or below the corresponding ear in an adjacent row. Material 74,7
6,78 is the surface of the specific member 90 and the surface of the member below the ear of the specific row
It is stacked in a vertically separated manner so as to rotate with respect to 82 and engage with the notch of a specific member. In this configuration, the bottom row of ears are oriented in a particular orientation to contact the top members 74,76,78 to align the ring and ears with the vertical slot. As the ears move down, the bottom row of ears engages surface 98 to rotate all rows of ears into alignment with the notches designed to receive them. The vertical raising motion of the tether then engages all ears simultaneously with their associated notches. Faces 68 of each ear upon disengagement of the ears
And the surface 80 of the member immediately below it simultaneously engages the bottom row of ears that engage surface 100 to align the ears for disengagement.

While one embodiment of the present invention has been illustrated in the accompanying drawings and described in the above detailed description, the present invention is not limited to the described embodiment, and parts and components may be used without departing from the spirit of the invention. It will be appreciated that many rearrangements, modifications and alternatives of the elements may be made.

Claims (7)

[Claims] 1. A connector for releasably fixing a tether (12) of a tension leg platform to the seabed, comprising a ring (50) attached to one of the tether (12) and the seabed, which has a central vertical axis. A ring (50) having (30) and at least one ear (58) extending horizontally along a radius centered on the central vertical axis, and adapted to receive the ring (50). A cylindrical receptacle (70) having a central vertical axis attached to the tether (12) and the other of the seabed, and a pivoting device, wherein the cylindrical receptacle (70) is the main guide. Surface (80, 82) and two vertical slots (104) so that when the tether (12) is lowered for fixing to the seabed, the ears (58) are guided by the two main vertical guide surfaces. (104) will be guided to one side And sea urchin arranged two vertical slots (104), receiving said ears (58), a notch which engages with the ear (92)
And vertically aligned with the vertical slot to assist in guiding the ear (58) in a direction aligned with the notch (92) when the tether (12) for fixing to the seabed is lowered. The engagement guide surface (98) is vertically aligned with the notch (92), and when the tether (12) is disengaged from the seabed, the ear (58) is connected to the vertical slot (). 104) and an auxiliary dissociation guide surface (100) for guiding in a direction aligned with the other, and the pivoting rotation device is fixed to the tether (12) and the one of the seabed and above it. The collar (44) on which the ring (50) is rotatably mounted around the central vertical axis.
A connector having an elastomeric assembly (36) also secured to. 2. The connector according to claim 1, wherein the pivoting device is a flange (32) provided at a lower end of the tether (12).
And the point (28) on the central vertical axis of the ring (50)
Flange (3) with a hemispherical concave surface (26) centered at
2) and the centering ball (5) provided on the ring (50).
2) to the point (2
8) is a hemispherical convex surface (54) centered on 8) and has substantially the same radius of curvature as the hemispherical concave surface (26) of the flange (32) and slides on the hemispherical concave surface (26). Centering ball (5) with a hemispherical convex surface (54) in dynamic engagement
2), wherein the elastomer assembly (36) is fixed to the tether (12) via the flange (32). 3. The connector according to claim 1 or 2, wherein three ears (58) extend from the ring (50), and the three ears (58) include the ring (50). ), The cylindrical receptacle (70) is fixed to the inner wall of the receptacle, and three members (74, 76, 78) fixed to the inner wall of the receptacle, and the inner wall of the receptacle below the three members. And an annular ring (94) mounted on each of the three members (74, 76, 78), and each of the three members (74, 76, 78) has the main guide surface (80, 82) on the upper surface thereof. The notch (92) below, the vertical slot (104) is formed between each of the three members, and the annular ring (94) defines the auxiliary engaging guide surface ( 98) and the auxiliary dissociation guide surface (100). 4. The connector according to claim 3, wherein each of the three members (74, 76, 78) has two inclined main guide surfaces (80, 82) and two lower inclined surfaces. (88,90),
A connector having an inverted U shape having vertical side walls (84, 86) and the notches (92). 5. The invention according to any one of claims 1 to 4
A connector according to paragraph (4), wherein the elastomeric assembly (36) has a plurality of elastomeric elements (4) coupled together.
0), each elastomeric element (40) being molded into a portion of a hemisphere having a radius centered at a point (28) on said central axis. 6. A connector as claimed in any one of claims 1 to 5, wherein the elastomeric assembly (36) is on a portion of a hemisphere having a radius centered on a point (28) on the central axis. A connector including a molded reinforcing member (42) having rigidity. 7. The invention according to any one of claims 1 to 4
The connector according to paragraph (1), wherein the ear (58) has two slanted upper surfaces (62, 64) and two slanted lower surfaces (66, 6).
8) A diamond-shaped connector that includes and.