Device and Method for Disconnecting Jammed Subsea Wet-Mate Connectors

Description

CROSS-REFERENCE TO RELATED APPLICATIONS

This application claims priority to Brazilian Application No. BR1020240074726 filed on Apr. 17, 2024, the disclosure if which is expressly incorporated herein by reference in its entirety.

FIELD OF THE INVENTION

The present invention is part of the field of subsea equipment. More specifically, the present invention is related to a device and method for disconnecting stuck subsea connectors due to sediment deposition.

BACKGROUNDS OF THE INVENTION

Some wet-mate type subsea electrical connectors may suffer deposition of a layer of sediments, particularly chalcomagnesian sediment, due to failures in the strategy adopted for the cathodic protection. Over years of operation, these deviations cause the deposition of sediments that strongly bind the equipment and make it impossible to disconnect the same by means of a ROV (Remotely Operated Vehicle). The chalcomagnesian layer becomes quite stable in deep waters, requiring great efforts to be broken. In this way, in many cases, the ROVs are unable to remove the wet-mate connectors, and destructive techniques must be used to recover the subsea equipment connected to such connectors.

A wet-mate connection system consists of an electrical jumper with a wet-mate connector at each end. It is used to interconnect two subsea pieces of equipment, such as an umbilical termination or a Vertical Connection Module VCM to a pumping system. If the wet-mate connectors become stuck, the jumper can be cut to separate the subsea equipment; however, the wet-mate connectors will continue to occupy the space that should receive a new component. In this way, the equipment would have to be lifted by a large vessel and the stuck wet-mate connectors would be removed, also with great effort, on board the vessel. The subsea equipment would then be placed back on the seabed ready to receive a new wet-mate connection system.

Cutting the jumper alone can be detrimental to the analysis of an electrical system failure, making it difficult to identify the root cause of the defect. In addition, the logistics of mobilizing large vessels to lift the subsea equipment is very costly in both time and money.

Therefore, it would be desirable to have a means of disconnecting the wet-mate connectors still jammed on the seabed.

Document CN219275730U, titled “Hot-stab hydraulic drawing tool for deep sea Christmas tree well”, discloses a hot-stab hydraulic drawing tool for a Christmas tree, which comprises a hydraulic cylinder and a sliding sleeve. On the outside of the body of the outer cylinder, the upper part of the sliding sleeve is attached with a connecting arm, and the upper part of the connecting arm is equipped with a handle that facilitates the gripping of the mechanical arm of the robot from the seabed through the connecting assembly. Referring to FIGS. 1 to 3, the ROV grasps the handle 12 of the device by mechanical gripping, centers the device on the positioning block 3, and fixes the positioning block 3 on the male head 702 of the Hot-stab device 7 to complete the preliminary positioning. Then, the alignment device causes the hook 4 and the T-handle 703 on the hot-stab device 7 to complete the connection and finish the final installation. Finally, the hydraulic cylinder 1 is actuated to make the hydraulic cylinder 1 stretch, and the hook 4 rises with the sliding sleeve 2, and the reverse tension support is generated between the positioning block 3 and the Christmas tree panel 6, and the disassembly of the male head 702 of the hot-stab device 7 is completed by means of the continuous extension of the hydraulic cylinder 1.

Document US2015136406, titled “Subsea intervention plug pulling device”, discloses a plug pulling device including an elongated housing comprising a production tree connection interface, a displacement tool arranged within and along a substantial length of the housing and comprising a distal end configured to be coupled to a pipe plug, and a seal arranged within the housing and formed around a portion of the displacement tool. The seal isolates a first portion of the housing from a second portion of the housing. The second part of the housing is adjacent to the production tree connection interface. The shift tool is configured to move partially in and out of the first portion of the housing when a pressure differential exists between the first portion of the housing and an environment external to the first portion of the housing. In a second aspect, this document discloses a subsea intervention device. The subsea intervention device includes an elongated housing including a production tree connection interface. The subsea intervention device further includes a displacement tool arranged within and along a substantial length of the housing and having a distal end configured to be coupled to a pipe plug. The subsea intervention device also includes a seal arranged within the housing and formed around a portion of the shift tool. The seal isolates a first portion of the housing from a second portion of the housing. The second part of the housing is adjacent to the production tree connection interface. The shift tool is configured to move partially in and out of the first portion of the housing when a pressure differential exists between the first portion of the housing and an environment external to the first portion of the housing.

Document WO2012149445A1, titled “Emergency disconnect system for riserless subsea well intervention system”, discloses a method for riserless subsea well intervention including: lowering a pressure control assembly (PCA) (100) from a vessel to a subsea production tree; attaching the PCA to the tree; lowering a control pod (340) from the vessel to the PCA using an umbilical; attaching the control pod to the PCA; lowering one end of a fluid conduit (355) from the vessel to the PCA; and attaching the fluid conduit to the PCA using a dry break fitting (200). In another embodiment, a pressure control assembly (PCA) for riserless subsea well intervention includes: a wellbore formed therethrough; a production tree adapter having a connector for attaching the PCA to a subsea production tree and a sealing sleeve for engaging an internal profile of the tree; a frame connected to the adapter; a fluid sub connected to the adapter and having a port in communication with the wellbore; an isolation valve connected to the fluid sub and operable to close the wellbore; a blowout preventer (BOP) device connected to the isolation valve and operable to shear a work string and close the wellbore; an accumulator for storing pressurized hydraulic fluid to operate the BOP; a tool housing connected to the blowout preventer; a control pod receptacle connected to the structure and having a base for receiving a control pod, a lock operable for engaging the control pod, and an actuator for operating the lock; and a manifold connected to the structure and having a dry-break fitting coupling for receiving a mating coupling connected to a fluid conduit and operable to provide fluid communication between the fluid conduit and the wellbore.

SUMMARY OF THE INVENTION

The present invention comprises a device capable of imposing on the subsea wet-mate connector 7 a disconnection force greater than that of the ROV manipulator. This is made possible by the action of high-pressure hydraulic cylinders 2 that move an extractor base 3, which purposefully forces the disconnection of the connector 7. In this embodiment, the invention has a structure 1 that accommodates the other components, in addition to providing structural stiffness against the forces that arise when the device is activated. The device weighs approximately 30 kg and is easily transported by the ROV. In other words, the ROV could already dive with the device in its drawer every time it is going to perform an operation to disconnect wet-mate connectors. Thus, if it is detected that it is impossible to disconnect the system using the ROV manipulator, the device would be immediately activated, reducing the planning time for solving the problem.

The present invention substantially increases the chances of disconnecting the subsea wet-mate system without causing damage to the equipment (or connectors), eliminating the need to charter large vessels and maintaining the integrity (without destroying any component of the system) of the subsea equipment for subsequent investigation of failures.

BRIEF DESCRIPTION OF THE DRAWINGS

The present invention will be described below with reference to typical embodiments thereof and also with reference to the appended drawings, in which:

FIG. A is a perspective view of a first embodiment of the device for disconnecting subsea wet-mate connectors according to the present invention;

FIG. B is a further perspective view of the first embodiment of the device for disconnecting subsea wet-mate connectors according to the present invention;

FIG. C is a representation of the first embodiment of the device of the present invention in operation;

FIG. D is a perspective view of a second embodiment of the device for disconnecting subsea wet-mate connectors according to the present invention;

FIG. E is a representation of the second embodiment of the device of the present invention in operation;

FIGS. F1 and F2 are representations of the hammer according to the second embodiment of the device of the present invention.

FIGS. G1 and G2 show the chalcomagnesian layer in an unstuck connector on the deck of the vessel.

FIG. H shows fragments of the chalcomagnesian layer immediately after unsticking the connector on the seabed.

DETAILED DESCRIPTION OF THE INVENTION

Specific embodiments of the present disclosure are described below. In an effort to provide a concise description of these embodiments, all features of an actual implementation may not be described in the specification. It should be appreciated that in the development of any actual implementation, as in any engineering or design project, numerous implementation-specific decisions must be made to achieve the specific objectives of the developers, such as compliance with system-related and business constraints, which may vary from one implementation to another. In addition, it should be appreciated that such a development effort may be complex and time-consuming, but would nevertheless be a routine design and manufacturing undertaking for those of ordinary skill having the benefit of this disclosure.

With reference to FIG. A and FIG. B, the device of the present invention consists of a structure 1 comprising an upper part 1.5 that connects two parallel side niches 1.4, each niche 1.4 having space inside to house, each one, a double-acting hydraulic cylinder 2 and an extractor base 3 and additional space to allow displacement of a piston 2.1 of the hydraulic cylinder 2 and the extractor base 3 in the longitudinal direction of the niche 1.4. The hydraulic cylinders 2 are connected in parallel to each other and are fixed to the niches 1.4 by means of the fixing structure 1.2, which can be a hollow panel for fixing by screws or rivets as illustrated in the examples of FIG. A and FIG. B.

The upper part 1.5 of the structure 1 further has a rod 1.1 to be gripped by the mechanical arm of the ROV in order to be correctly positioned over the connector 7 to be disconnected. The structure 1 further has support elements 1.3 so that the structure 1 rests on the connector 7, as will be seen later.

The hydraulic cylinders 2 receive hydraulic fluid from the tubes 4, which can in turn receive hydraulic fluid from the ROV's own hydraulic circuit or from any other external source. This actuates the pistons 2.1 of the hydraulic cylinders 2, causing the pistons 2.1 to extend in the longitudinal direction of the niches 1.4 and push the extractor base 3, as can be seen in FIG. B. When this occurs, each projection 3.1 of each extractor base makes contact and pushes the connector 7 with sufficient force to break the sediments deposited in the connector 7, releasing the same. The extractor base 3 shown in FIG. A and FIG. B has two projections 3.1, which is the preferred embodiment, but the extractor base 3 may have one or more projections 3.1 without limitation, the number of projections 3.1 being chosen based on the shape of the connector 7 to be disconnected.

FIG. C illustrates the structure 1 of the first embodiment of the invention in operation. The connector 7 illustrated in FIG. C is a particular connector that has a handle 7.1 that must be rotated by the ROV to release the lock 7.2, which prevents accidental disconnections. The connector 7 is connected integral with the panel 8 of the subsea equipment and is aligned by means of the tube 8.1. Obviously, this particular connector 7 is merely exemplary, so that the present invention is not limited to use with this specific connector.

Preferably, the upper part 1.5 and the niches 1.4 of the structure 1 are formed in such a way as to engage tightly around the particular connector 7 that is to be operated. This assists the proper functioning of the connection device. Optionally, the upper part 1.5 and the niches 1.4 can be adjustable so as to suit the use of different types of connectors, so that it is not necessary to take more than one device with different adjustments for maintenance campaigns.

As illustrated in FIG. C, the structure 1 of the connection device according to the first embodiment of the present invention is positioned integral with the panel 8 of the subsea equipment with the support elements 1.3 supported on the rigid structure of the connector 7. The hydraulic cylinders 2 are actuated by means of hydraulic fluid received from the tubes 4. This moves the pistons 2.1 of the hydraulic cylinders, which in turn push the extractor base 3 in the opposite direction to the panel 8. The projections 3.1 of the extractor base 3 make contact with the rigid structure of the connector 7, creating a separation force between the connector 7 and the panel 8.

FIG. D and FIG. E illustrate a second embodiment of the disconnection device of the present invention. In this embodiment, the extractor base 3 has extenders 5 instead of projections 3.1. The extenders 5 are moved together with the extractor base 3 when the hydraulic cylinders 2 are actuated, making contact with the base of the handle 7.1 at the rear of the connector 7. The extractor base 3 represented in FIG. D and FIG. E has two extenders 5, which is the preferred embodiment; however, the extractor base 3 can have one or more extenders 5 without limitation, the number of extenders 5 being chosen based on the shape of the connector 7 to be disconnected. As an example of connector 7, as illustrated in FIG. E, when applied to equipment it can be the three-pin type developed for PUMOs (Pump Modules) or a SpecTRON connector 8, but not limited to these.

The other elements of the disconnection device in this second embodiment are equivalent to those of the first embodiment described previously, that is, the description above for the first embodiment of the invention with regard to the structure 1, upper part 1.5, niches 1.4, support elements 1.3, fixing structures 1.2, rod 1.1, hydraulic cylinders 2 and pistons 2.1, is applied to these elements of the second embodiment of the invention. The cradle 17 serves to support the tool on the connector 7, made of Tecnil, and is useful to avoid damaging the connector 7. This can be seen in FIG. D.

The positioning of the structure 1 and the actuation of the hydraulic cylinders 2 also occur in the same way, as seen in FIG. E. The structure is positioned integral with the panel 8 of the subsea equipment and engaged into the connector 7, which in this case has a different handle 7.1, and is where the separation force transmitted from the pistons 2.1 to the extractor base and to the extenders 5 will be applied.

The second embodiment of the present invention may optionally include a hammer 6 consisting of a hydraulic motor rotating a cam. In the event that the previous procedure using the separation force fails, the hammer 6 may be actuated to cause controlled impacts on the connector 7 to damage and break the layer of sediments that enter the connector 7. When rotating, the cam of the hammer 6 retracts a mass that compresses a spring. In a given position, the cam has a recess that releases the mass-spring assembly. The spring expands, pushing the mass and causing an impact on structure 1 and, consequently, on connector 7. Since the cam movement is cyclical, repeated impacts occur, resulting in a strong vibration. This vibration weakens the sediment layer, which causes obstruction of connector 7.

The hammer 6 will be described in greater detail below with reference to FIGS. F1 and F2.

The hammer 6 consists of a hydraulic motor 10 and has hydraulic tubes separate from the cylinders. The hydraulic fluid can be supplied to the tubes by the ROV's hydraulic circuit or by any other source, as can be seen in FIG. F2, bottom part, where it is possible to see the access connections of the hydraulic hoses to the motor. The hydraulic motor 10 has an eccentric 13 coupled to its shaft. When rotating, the eccentric 13 makes contact with the roller 16 of the hammer shaft, displacing the same as the radius of the eccentric 13 increases. The displacement of the roller 16 (and of the entire structure of the hammer) causes the compression of the spring 14, whose elastic constant determines the intensity of the impact. When the eccentric reaches the end of its stroke, the roller 16 is released and the spring 14 pushes the mass of the hammer 15 against the bottom of the vessel 9, generating an impact. The cycle repeats as the hydraulic motor 10 rotates: one impact for each revolution. Vessel lids 12 close each opening of the vessel 9 to prevent water from entering, and a clamp 11 attaches the motor 10 to the structure of the extractor base 3.

The impact force of the hammer 6 depends on the elastic constant of the spring 14 and the stroke of the hammer shaft. For example, spring 14 may have a spring constant of 11.6 kgf/mm (113.76 N/mm) and a maximum stroke of 13 mm, which would result in an impact of 150 kgf (1471 N). Preferably, the impact force of the hammer is limited to up to 14 kgf (137.3 N) so as not to damage connector 7.

Although not shown, the person skilled in the art will immediately realize that the connection device according to the first embodiment of the present invention illustrated in FIGS. A, B and C can be adapted to receive hammer 6.

The device of the present invention is compact and can be manufactured with relatively light but rigid materials, totaling approximately 30 kg considering the entire structure 1, hydraulic cylinders 2, extractor base 3, hammer 6 and tubes 4, and is easily transported by the ROV. Due to its relatively small size and weight, the ROV is capable of diving with the device of the present invention in its drawer, with the hydraulic channels properly connected, every time it is going to perform a disconnection operation of wet-mate connectors. Thus, if it is detected that it is impossible to disconnect the system through the ROV manipulator, the device is put into use, without the need to plan a new and costly campaign that would use destructive methods.

The present invention also provides a method of using the disconnection device, comprising the steps of:

• • Positioning the structure 1 so that it is integral with the panel 8 of the subsea equipment and supported on the wet-mate connector 7;
  • Activating the hydraulic cylinders 2 until the wet-mate connector is disconnected; and
  • Optionally, interrupting the activation of the hydraulic cylinders 2 and activating the hammer 6 until the sediment layer is broken.

Although aspects of the present disclosure may be susceptible to various modifications and alternative forms, specific embodiments have been shown by way of example in the drawings and have been described in detail herein. But it should be understood that the invention is not intended to be limited to the particular forms disclosed. Rather, the invention is intended to encompass all modifications, equivalents and alternatives that fall within the scope of the invention as defined by the following appended claims.