Skid Docking and Anchoring System with Couplings and Associated Methods

The present disclosure belongs to the field of subsea operations and underwater exploration, more specifically referring to a stabilization system for a ROV (Remotely Operated Vehicle) for pre-pull-in operations, where the ROV is responsible for maintaining a moonpool, through a skid latch structure associated with a docking equipment.

Pre pull-in operations play a crucial role in the oil and gas industry in subsea environments, where equipment installation is complex and delicate. These operations refer to the preparatory steps carried out before pulling (pull-in) or installing subsea equipment, such as pipeline, risers and cables, for production, exploration or intervention operations in subsea wells.

Currently, pre pull-in operations are carried out with a combination of advanced technologies and refined methods. This includes the use of dynamic positioning systems on support vessels, which ensure an accurate position over the installation site. In addition, the use of remotely operated subsea vehicles (ROVs) allows visual inspections and precise manipulation of equipment on the seabed prior to the pull-in.

Before the actual pull-in operation, a series of checks and preparations are carried out, which may include detailed inspections of subsea equipment (such as a riser balcony), functional tests, and verification of structural integrity (e.g., integrity of dogs-launching devices, ensuring that all components are adequately prepared for the installation process.

In addition, pre pull-in operations also involve detailed logistical coordination, requiring all materials and equipment to be readily available at the operating site.

In this sense, the main difficulties of the systems for current pre pull-in operations are: assembly, lack of stability, lack of flexibility and lack of protection of equipment in subsea maintenance and underwater inspection operations of bellmouths.

Document GB2323907A describes a method and apparatus to connect underwater conduits without the need for divers; that is, remotely. More specifically, it relates to a method and apparatus capable of performing the diver-free connection of underwater flowlines-both flexible and rigid-in any combination with each other, and the connection of these flowlines to underwater structures, such as flowline bases, underwater Christmas trees, templates or the like.

The present disclosure, unlike document GB2323907A, is a system specially adapted for docking operations in bellmouths, to carry out pre pull-in operations, providing greater stability in the maintenance of its structures; for example, in the softening of dogs.

Document EP2825720A1 presents systems and methods for interacting with subsea production equipment during operation. It features various forms of sealing and fluid transfer elements, as well as flow control systems, intended to facilitate fluid communication between interface tools and subsea equipment. In addition, the document describes an interface system that features a skid removably attached to the underside of a ROV, containing additional equipment, such as tools for maintenance operations.

However, like the other technologies of the state of the art, document EP2825720A1 fails to provide a specialized docking system for stabilization of a ROV in pre pull-in operations.

The present disclosure proposes a skid docking and anchoring system with couplings, which comprises a docking structure, an interchangeable skid and a coupling skid. The docking structure is formed by welded plates comprising a back plate and a front plate. In addition, the back plate features a groove for vertical attachment to the riser balcony. The front plate comprises at least two front handles, at least four keys located in the central region of the front plate, and at least four coupling supports at the bottom of the front plate. Additionally, the coupling skid comprises a welded truss structure, four coupling pins, and a tool basket.

The skid docking and anchoring system, shown in, is composed of the following elements: a docking structure (), an interchangeable skid () and a coupling skid (). The docking structure () is fixed with the help of a ROV on the riser balcony (), allowing the subsequent integration between the other components.

The interchangeable skid, as shown in, is an interface between a remotely operated vehicle (ROV) and the coupling skid. The interchangeable skid holds the floats and ballasts necessary to maintain the stability of the ROV when mounted to the coupling skid, in addition to being the interface between it and the ROV.

The docking structure is a static device that must be positioned and fixed on the riser balcony, so that it acts as an anchor point for the coupling skid, and thus the ROV.

The docking structure (), as shown in, is formed by welded plates, so that its back plate () allows positioning on the riser balcony. The fixation is made by means of screws that must be positioned in keys, located in the lower region of the front plate of the docking structure, as shown in, so that the fixation is made by compressing the docking structure against the riser balcony, with the help of four screws tightened in their respective keys by the ROV itself.

In addition, the docking structure () has front handles () so that the ROV can guide it for attachment to the riser balcony. This fixation is made by means of screws that must be positioned in keys (), located in the lower region of the front plate () of the docking structure, as shown in, so that the fixation is made by compressing the docking structure against the riser balcony, with the help of four screws tightened in their respective keys by the ROV itself.

In addition, the docking structure () has four coupling supports () at the bottom of the front plate () for positioning the coupling skid.

The coupling skid (), shown in more detail in, is composed of a welded truss structure (), four coupling pins () and a tool basket (). The coupling pins () are secured by screws, while the tool basket () is positioned in a dedicated cradle in the center of the truss. The tool basket () has a crank () for opening and closing its lid, giving access to the tools stored inside.

The coupling skid is connected to the interchangeable skid () by means of screws, as well as the couplings, which are responsible for allowing the anchoring of the entire device to the docking structure, which work hydraulically, being normally closed and actuated to allow the opening of the locking pins.

With the help of a lifting structure launched from a pipe laying support vessel (PLSV), the docking structure is taken to the vicinity of the riser balcony. With the help of a ROV, holding the front handles, the rear plate of the docking structure is positioned in a recess of the riser balcony.

Then, the ROV turns the crank of the tool basket, removing screws, one by one, being fixed in the central keys of the front plate of the docking structure. When the screws are finished, the crank returns to its original position to close the tool basket.

With the docking structure now fixed, the lifting structure can be returned to the PLSV, as well as the ROV, to receive the equipment needed for maintenance/cleaning operations of the balcony riser and its moonpool.

With this equipment, the ROV can return to the docking plate and fix the four coupling pins of the coupling skid to the four supports of the docking structure. With this, it is possible to minimize the relative movement between the riser balcony and the ROV, facilitating and optimizing maintenance and cleaning procedures.

While aspects of this 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 in this document. But it must be understood that the disclosure is not intended to be limited to the specific forms disclosed. Instead, the disclosure must cover all modifications, equivalents, and alternatives that fall within the scope of the disclosure, as defined by the following attached claims.