Mechanism for coupling and supporting a bend stiffener with single external actuation

Abstract

The present invention relates to coupling / uncoupling and support mechanisms for connecting bend stiffeners to bellmouths, and aims to optimize pull-in and pull-out operations, reduce operating costs and times, and also completely replace shallow dives by operations without associated man-hours exposed to risk, such as those carried out using remotely-operated vehicles (ROVs). The proposed solution envisages a mechanism for coupling / uncoupling and supporting a bend stiffener, comprising a frontal actuation means, which has the feature of being easy to access and operate using ROVs, thereby replacing the multiple latch mechanisms used previously.

Description

Coupling and support mechanism for bend stiffener with single external drive Field of the invention:

[0001] The present invention relates to the oil and gas industry; more specifically, to the deepwater oil and gas production system. This system utilizes technologies, mechanisms, or devices that utilize risers in their compositions. Therefore, the coupling process between risers and / or other structures is highly relevant in this segment. Thus, more specifically, the present invention relates to coupling and support mechanisms for connecting Bend Stiffeners to Bell Mouths. Fundamentals of the invention:

[0002] Flexible risers are typically connected to offshore oil production platforms by devices that decouple the riser's tensile force from the lateral loads caused by the floating unit's displacement. Tension is supported near the platform deck (hang-off), and lateral loads are transferred to a connecting device located near the bottom of the platform hull. A typical example of this widely used connecting device is the so-called bell mouth. Decoupling the tensile force from the lateral loads of flexible risers provides significant operational benefits for riser technology, including increased service life, but is not limited to this.

[0003] Although the post-installation configuration is quite While favorable for the operational life of the flexible riser, the submerged conditions of the Bell Mouth create technical operational challenges for riser pull-in and pull-out operations. These challenges include low operational efficiency during the riser installation stages and unfavorable conditions for divers to perform safety-related tasks (HHER: man-hours exposed to risk).

[0004] Regarding low operational efficiency, an analysis of the main causes of non-productive time (NPT) for Pipe Laying Support Vessels (PLSVs) revealed significant time loss due to environmental conditions that prevent shallow diving during pull-in operations. This diving operation is necessary to ensure the correct connection of the Bend Stiffener to the bell mouth. To reduce NPT, it was identified that one appropriate action would be to develop a new bell mouth to reduce the resistance to the Bend Stiffener connection, increasing the reliability of this operation and eliminating the need for shallow diving in parallel with the PLSV.

[0005] Regarding unfavorable conditions for divers, the Bell Mouth is usually located in shallow water, in a region strongly influenced by waves and flows induced by the movement of the production platform. Besides being an inherently dangerous activity, the use of equipment that requires divers to operate in this region, combined with high water mass movements, poses additional risks to the diver's physical integrity. It is important to note that shallow diving was recently identified as one of the work activities that pose a greater risk to the physical integrity of the professional, with fatal accidents even being recorded in recent years. State of the art:

[0006] The first Bell Mouths, as revealed in document US5947642, adopted the philosophy of always requiring shallow diving during riser installation and de-installation operations. Prior to the arrival of the PLSV and the subsequent transfer of the riser to the platform, diving was required to check the operation of the Bell Mouth's locking mechanism.

[0007] During the transfer of the PLSV riser to the platform, the shallow diver installed hoists connecting the Bend Stiffener to the platform hull to prevent the Bend Stiffener from falling if the pull-in fuse cables were to prematurely rupture due to overload due to excessive interference with the riser coupling at the bell mouth. After the pull-in operation was complete, the diver would position the bell mouth dogs in the locked position and remove the hoists to prevent the Bend Stiffener from falling.

[0008] With the advent of the Diverless Bell Mouth (BSDL), as can be seen in document BR102018011452-2, the limitations listed above were overcome with the development of a locking mechanism using tabs, which eliminates the need for shallow diving during pull-in operations, eliminating the need for the locking step by divers. Furthermore, the optimized geometry of the Bend Stiffener Helmet reduces resistive forces during the process. coupling, increasing the reliability of sizing the fuse cables and thus avoiding the need to install hoists.

[0009] Despite the advances listed above, the development of the BSDL prioritized increasing operational efficiency during pull-in operations. Regarding diver safety, despite significant improvements to the human-equipment interface, the BSDL still required shallow diving during pull-out operations.

[0010] To solve this problem, a hydraulic actuation system was developed whose unit is coupled to each of the pawl mechanisms, thus requiring up to 8 actuators per BSDL, whose hydraulic power is supplied, via the control umbilical, by the platform's HPU system.

[0011] Even with the significant improvements, the above set of solutions (BSDL and Hydraulic Actuation) still has some gaps that can be improved, both from an economic standpoint (reducing equipment costs) and from a safety standpoint, for example, by completely replacing shallow diving with operations without associated HHER, through the use of remotely operated vehicles (ROVs). Such improvements should primarily be related to the following situations: - In the event of a hydraulic actuation failure by the platform, the handle mechanism (provided for in BDSL) remains as a backup with diving, as the handles do not have optimized geometry for ROV operations. Furthermore, due to the typical size of ROVs and the limited reach compared to human manipulation, some handles do not are accessible by this actuation method. Therefore, there would be a need for immersion support due to access limitations. - A significant reduction in the number of actuators / support components would allow a single actuation system, either mechanical or hydraulic, to open / close the Flexural Stiffener support system.

[0012] Thus, evaluating the above, it is clear that the points addressed open space for solutions that mitigate such limitations, such as the difficult execution of the operation of the handles by ROV in case of failure due to the location of the handles and the unification of the actuation system for support.

[0013] Thus, evaluating the general concept of the BSDL, together with the schematic of adjacent bell mouths, it is observed that, in the event of a hydraulic failure by the platform, ROV operation of the handles would be difficult, since such a device was designed for human interface. Furthermore, some handles are located in an area difficult for ROVs to access.

[0014] The State of the Art also reveals other documents related to the object of the present invention.

[0015] Document US7967070 discloses a connector for use in subsea structures, which has a shaft and comprises a funnel and a locking assembly, one of the purposes of which is to inhibit unwanted movement between the assembly and its components. The locking assembly includes a base plate, a cam plate, and / or other components that operate to lock the assembly to the shaft. Specifically, the cam plate only serves as a control function to lock or unlock the locking dogs. Furthermore, one of the connector's versions can be installed using a remotely operated vehicle (ROV) without the need for divers.

[0016] Document US8573305 discloses an automatic release system for a riser, which includes a guide funnel assembly that receives a shaft coupled to the riser. The method proposed in this document envisages the entire operation being handled by an ROV.

[0017] Document PI1106877-9 discloses an accessory for installing and positioning lines connected to the hull of oil production units. The proposed technology ensures the coupling of the assembly, consisting of a cap and bend restrictor, to the bell mouth.

[0018] Document BR102018011452-2 discloses a coupling system between a Bend Stiffener and a Bell Mouth, which includes reliable automatic locking to the point that the shallow diving step is dispensed with in this operation. This document discloses a coupling system between a Bend Stiffener and a Bell Mouth, comprising a plurality of locking mechanisms in which each locking mechanism is fixed externally to the Bell Mouth and comprises a movable pawl positioned at a downward angle, in which the pawl accesses the interior of the Bell Mouth and is actuated by an elastic element adapted to exert pressure on the pawl towards the interior of the Bell Mouth. In particular, the document does not present a mechanism compatible with ROV pull-in / pull-out operations.

[0019] Although the documents cited in the State of the Art reveal matter related to the subject matter of the present invention, these documents reveal different applications, such as: the temporary pull-in connection between the Bend Stiffener and the Traction Head.

[0020] The proposed invention allows for the automatic coupling of the helmet-bend stiffener assembly with the Bell Mouth during the pull-in of the riser, an operation that comprises considerably different particularities in relation to what was proposed in the State of the Art, notably due to the simplification of the Bell Mouth locking devices.

[0021] As a main innovation, for the riser disconnection procedure, pull-out, the proposed invention allows the decoupling of the Bend Stiffener from the Bell Mouth during the riser pull-out without the use of divers, since it would be fully operable through a remotely operated vehicle (ROV). Objectives of the invention:

[0022] The present invention relates to coupling / decoupling and support mechanisms for connecting Bend Stiffeners to Bell Mouths. It aims to reduce operational costs by reducing the acquisition cost of riser supports (simplifying components and reducing the number of actuators) and also to completely replace shallow diving with operations without associated HHER, such as with the use of a remotely operated vehicle (ROV). The proposed solution provides a coupling / decoupling and support mechanism for Bend Stiffeners that comprises a front-mounted actuator, with the characteristic of being easily accessed and operated by ROVs; thus replacing the multiple pawl mechanisms previously used. Brief description of the figures:

[0023] Figure 1 illustrates the coupling / decoupling and support mechanism of the Curvature Stiffener containing the front drive means, according to the present invention.

[0024] Figure 2 illustrates the Bend Stiffener coupling / decoupling and support mechanism by identifying the Bell Mouth structural body, the Bend Stiffener Helmet, and the regions that are impacted by the locking mechanism.

[0025] Figures 3A and 3B illustrate the articulated fork mechanism for supporting the Curvature Stiffener Helmet in the closed and open modes respectively, according to the present invention.

[0026] Figure 4 illustrates four other possible variations of the Articulated Fork mechanism that can be applied in closed and open modes, according to the present invention.

[0027] Figure 5 illustrates the Articulated Fork mechanism for supporting the Curvature Stiffener Helmet during pull-in operation, according to the present invention.

[0028] Figure 6 illustrates the Articulated Fork mechanism for supporting the Curvature Stiffener Helmet in the closed position, in accordance with the present invention.

[0029] Figure 7 illustrates the Articulated Fork mechanism for supporting the Bend Stiffener Cap in the open position during pull-out operation, in accordance with the present invention. Detailed description of the invention:

[0030] An overview of the Bend Stiffener coupling and support mechanism proposed in this invention is shown in Figure 1. In general, the external geometry of the Bell Mouth is similar to that of the BSDL; however, replacing the multiple pawl mechanisms with a front actuation means M, with the characteristic of being easily accessed and operated by ROVs.

[0031] As previously mentioned, the structural body of Bell Mouth 1, as well as the Curvature Stiffener Cap 2, change little in relation to that described in the BSDL (document BR102018011452-2), except in the regions impacted by the new locking mechanism proposed by the present invention and as represented by region R highlighted in Figure 2.

[0032] The multiple BSDL pawls supporting Bend Stiffener Cap 2 are replaced by Articulated Fork 3 pivoted on Axis 4, with a fixed position in the Bell Mouth, as illustrated in Figures 3A and 3B. Articulated Fork 3's natural position is in the closed condition; that is, supporting Cap 2, as illustrated in Figure 3A. During the pull-in operation, Cap 2 acts to open Articulated Fork 3, allowing its coupling to the structural body of Bell Mouth 1, as illustrated in Figure 3B. After connecting Cap 2, Articulated Fork 3 returns to its natural position with the aid of a Return Element 6, which may be a helical spring, as shown in Figure 3B.

[0033] The configuration shown in Figures 3A and 3B of the Articulated Fork mechanism is the preferred solution for mechanism. However, it is important to note that there are several other configurations for this solution, as exemplified in Figure 4.

[0034] In order to guide the movement of the mechanism during the pull-in process, the structure of Bell Mouth 1 is manufactured with Bearings 5 ​​that are positioned at its interface with Articulated Fork 3. These bearings are selected with material with tribological properties suitable to support the weight of Helmet 2 and allow the smooth movement of Articulated Fork 3 in a submerged environment, as illustrated in Figure 5.

[0035] After the pull-in process is completed, in order to avoid any spurious movement of the Articulated Fork 3 during the riser operation, a Safety Lock 8 must be installed, preferably by ROV, to kinematically prevent the movement of the Articulated Fork 3 and avoid the risk of unintentional disconnection of the Bend Stiffener Cap 2, as illustrated in Figure 6.

[0036] For the pull-out operation, the ROV couples a Drive Spindle 7 to the Articulated Fork 3, so that the ROV itself exerts a force in the opposite direction to that exerted by the Return Element 6, allowing the disconnection of the Helmet from the Bend Stiffener 2, as illustrated in Figure 7.

[0037] As an alternative configuration, Return Element 6 can be replaced with a spring-return hydraulic cylinder, which allows the Bend Stiffener 2 Helmet to be disconnected remotely from the platform. The spring return is necessary for the cylinder to operate as per the configuration described in Figure 7; that is, with automatic pull-in operation, no hydraulic power required.

[0038] This alternative configuration offers considerable benefits by eliminating the need for ROV operation during pull-out operations. However, the possibility of using Drive Spindle 7 must be maintained in the design, as backup operation may be required in the event of hydraulic cylinder failure.

[0039] Therefore, with the proposed modifications, the invention guarantees advantages in relation to the State of the Art, namely: reduction in the cost of acquiring riser supports, mainly with the simplification of components and reduction in the number of actuators; optimization of access to the equipment by ROV, reducing operation time; lower maintenance costs; connection compatibility with the first-generation BSDL helmet; replacement of shallow diving operations by ROV operations; reduction in the number of hydraulic systems that need to operate simultaneously, thus reducing the probability of global failure of the mechanism, among others.

Claims

CLAIMS 1. Coupling / decoupling and supporting mechanism for a Bend Stiffener with external drive, characterized in that it comprises: a drive means (M) composed of an Articulated Fork 3; and Bearings 5 ​​that are positioned at the interface of the Bell Mouth 1 with the Articulated Fork 3.

2. Mechanism, according to claim 1, characterized in that the Articulated Fork 3 pivots on an Axis 4 when varying between the closed position and the open position.

3. Mechanism according to claim 1, characterized in that during the pull-in operation, the Cap 2 acts on the opening of the Articulated Fork 3.

4. Mechanism according to claim 3, characterized in that after connection with the Cap 2, the Articulated Fork 3 returns to its natural position with the aid of a Return Element 6.

5. Mechanism according to claim 4, characterized in that the Return Element 6 may be a coil spring. 6.Mechanism according to claim 1, characterized in that the bearings are selected with material with specific tribological properties for the function.

7. Mechanism according to claim 1, characterized in that it further comprises a Safety Lock 8 installed on the Articulated Fork 3.

8. Mechanism according to claim 1. characterized by the fact that for the pull-out operation, a Drive Spindle 7 is coupled to the Articulated Fork 3.

9. Mechanism, according to claim 5, characterized by the fact that the Return Element 6 is replaceable by a hydraulic cylinder with spring return.

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