The present invention relates to a system of subsea tools operated remotely from above the surface. More concretely the present invention concerns a device of remotely operated, tethered, subsea tools as indicated by the preamble of claim 1.

Background

There is a high demand for performing work and support to subsea operations in oil related and other industries, in rescue operations, in environmentally related operations, in research related operations with a high requirement for automation or at least remotely performed operation using unmanned subsea vehicles equipped with tools. At the same time it is important to use environmentally friendly concepts.

Lately, development has taken place in direction of making the tools themselves operable using small thrusters, thereby avoiding the use of rather bulky ROVs where their size and weight is not required. In this connection it would be convenient to establish a system that allows different subsea tools to be parked under water when not in use, thereby avoiding the time consuming operation of launching the tools from a vessel or station at or above sea level and to lift the tools back up every time an operation has been performed.

Objectives

It is thus an objective of the present invention to establish a system for the operation of remotely operated subsea tools, which is cost-effective and reliable and allows operations to be started and terminated with a minimum of manual involvement while avoiding method and systems having a negative effect on the environment.

The present invention

The objective indicated above is fulfilled by the device of remotely operated, tethered, subsea tools according to the present invention, as defined by claim 1.

Preferred embodiments are disclosed by the dependent claims.

The invention provides a subsea station comprising any number from two to a multitude of tethered subsea tools operable and controllable from above sea level, disconnected from the umbilical when not in use, rapidly connected to the umbilical and launched from the station when operation is required. The subsea station may be configured to operate one, two or more tools simultaneously as the need may be, comprising separate umbilical drums for each tool when two or more are required to operate simultaneously. The terms "tether" and "umbilical" are used as synonyms herein for a multi-functional cable between the subsea station and the tools as elaborated below.

The subsea station is typically provided with energy from an external source but may also have internal energy in the form of a battery pack or the like.

The term "tool" as used herein, refers to the entire movable unit comprising a functional tool, inspection unit, or data collection unit (such as a torque wrench, a saw, a cutter, a drill, visual inspection, NDT inspection, sonars etc), means for propulsion of the unit, as well as the interface for connection to an umbilical etc. When referring to the actual functional tool (saw, cutter, torque wrench, visual inspection, NDT inspection, sonars etc.) we use the term "functional tool". The (entire) tool, is also denoted a ROTT, which is short form of "remotely operated tethered tool".

All tools belonging to a station exhibit an interface connectable to the interface of an umbilical, the connection and disconnection operations typically arranged to be performed by simple movements of an actuator, such as a linear actuator operable by an electric, pneumatic or hydraulic motor. Preferably, the motor or motors for connection and disconnection are electric motors.

The interface of each individual tool may vary from tool to tool, but have a general structure allowing each tool to be connected to one and the same umbilical. The umbilical is generally arranged to provide energy to the tools in operation, to allow exchange of information to and from tools in operation and to provide a tether allowing the tools to be pulled back by force if required, such as during any kind of technical failure. The means for information exchange may have the form of fiberoptic cables as well as electric conductors.

When the tools are not in operation, they are parked in a parking site of a parking rack. Preferably all the parking sited of the rack are similar and all the tools are provided with a common surface element that corresponds to a surface element of the surface site in such a way as to be held securely in place when parked. When all the parking sites are similar or identical, any tool can be parked in any available parking site.

Parking of the tools are generally made in a manner in which the interface to be connected to the umbilical is pointed upwards and typically covered by a protecting cap. The tools may generally be said to exhibit a connecting end, which is the end having an interface to be connected to the interface of the umbilical and an end exhibiting the functional tool, which may be denoted the functional end or the working end. Usually, the tools are elongate with the connecting end and the working end arranged oppositely in relation to one another. In exceptional cases, however, the tools may deviate from this structure and have a functional tool arranged rather close to the connecting end. A tool may also be a combination tool exhibiting more than one functional tool, e.g. a grip arm and a torque wrench, a grip arm and a drill, etc.

The design and function of the individual tools 21 are not within the scope of the present invention and the discussion above is merely to better understand the general, common features of the parking of the tools in the parking rack 11. The tools are generally parked with their connecting end as the upper end, making the tool interface easily accessible for the umbilical interface without having to turn the tool around when it is pulled into the connection and launching station 12. This means that the surface of the tools adapted to the surface of the parking site, typically is the surface surrounding the functional tool, i.e. the end of the tool opposite the connecting end of the tool.

In the exceptional cases that the functional tool has a shape and/ or dimension that does not allow it to fit in a parking site. The tool is typically provided with a particular lateral extension having an adapted surface that fits the surface of the parking site, thereby allowing the functional tool to remain outside the parking site even when parked.

In the following, the present invention is described in more detail in terms of non-limiting embodiments illustrated by drawings, in which:

Figure 1A is a schematic top view of a device of remotely operated, tethered, subsea tools according to a first embodiment of the present invention.

Figure IB is a schematic side view of the device shown in Figure 1A.

Figure 2A is a schematic top view of a device of remotely operated, tethered, subsea tools according to a second embodiment of the present invention.

Figure 2B is a schematic side view of the device shown in Figure 2A.

Figure 3A is a schematic front view of a parking site and of part of a tool according to the present invention.

Figures 3B-3D provide schematic side views of the parking site and the tool shown in Figure 3A in different positions.

Figure 3E shows a schematic side view of a variant to the embodiments shown in Figures 3A-3D Figures 4A-4D are side sectional views of a connection and launching operation in accordance with the device of the present invention.

Figure 5 shows schematically different configurations of the parking rack according to the present invention.

The drawings are only intended to show the principle of the present invention in schematic and simplified form. Elements of standard type required to complete the pictures are omitted, such as power supplies, motors, pipes etc.

Figure 1A shows in a top view a subsea station 10 for remotely operated subsea tools 21. The depicted elements of the subsea station are a parking rack 11, two connection and launching stations 12, a chassis or housing 13, two umbilical drums 14 and a guidance means 16 for the umbilical between drum 14 and the connection point in the connection and launching stations 12. The guidance means mainly comprises guiding rolls as explained in relation to Figure 4A. The parking rack 11 surrounds the housing 13 to thereby constitute a compact overall design.

The parking rack is shaped as a full circle constituting the outer circumference of the subsea station and being pivotally arranged, thus allowing any one of the tools 21 to be positioned in front of each of the two connection and launching stations. The shown subsea station 10 is a dual station in the sense that two separate tools 21 may be operated at the same time, one connected to each of the umbilicals arranged on each of the two umbilical drums 14.

The tools 21 in the parking rack may all be different tools, but typically there will be at least two similar or identical tools of the kind that is most frequently used in order to be able to continue operation without requiring repair work performed even if a tool should fail.

When a tool 21 is required for operation, e.g. tool 21n, the parking rack is turned about its typical vertical axis until tool 21n is positioned adjacent to one of the connections and launching stations 12. All logical movement is handled from a computer above the surface. Then, the operator may send an instruction to a programmable logic controller (PLC) to connect the tool 21 to the corresponding umbilical 15. The PLC then automatically ensures that the required unity operations are performed to complete this task, involving a number of pre-programmed steps. At least one grip member controlled by at least one electric motor, grips the tool 21n in question and pulls it into the connection and launching station 12. There, typically, a protective cap 21b covering the tool's umbilical interface is removed and the free end of the umbilical is connected to the tool's interface. When the umbilical is connected, the tool is launched from the subsea station in a downward movement from the connection and launching station 12. The connection and launching stations can, in some embodiments, be divided into two zones, one for connection and one for launching, requiring another unity operation of transfer there between.

While use of pre-programmed PLCs are favourable in the sense of simplifying the work for the operator, such units may be combined with or replaced by other data-technical hardware and software solutions, as deemed appropriate by the person skilled in the art in the set-up of subsea stations according to the present invention.

One practical issue worth mentioning in this context is the optional possibility of including intelligent units in each tool provided with means for communication with other tools, allowing short distant information exchange between tools, independent of instructions from the surface. Such information exchange may also eventually lead to local subsea decision making not influenced by the operator.

Figure IB shows a side view of the subsea station of Figure 1A in a situation in which two tools 21 have just been launched from the station, one from each of the connection and launching stations 12. Figure IB also shows part of two umbilicals 15 and an optional dome 17 covering the upper part of the subsea station in order to prevent debris or live organisms to enter the subsea station from above. The dome may be transparent or non-transparent or non-transparent with the exception of one or more transparent windows.

Figure 2A shows an embodiment of the present invention in the form of a subsea station 20 exhibiting just one each of a connection and launching station 12, a housing 13, an umbilical drum 14, and guidance means 16 for the umbilical between drum 14 and the connection point in the connection and launching stations 12. This station 20 thus is able to operate one tool at the time, connected to the umbilical from position 21n by means of the connection and launching station 12.

Figure 2B shows a side view of the subsea station of Figure 2A in a situation in which a tool 21 has just been launched from the connection and launching stations 12. Figure 2B also shows the parking rack 11, the connection and launching station 12 and part of the umbilical 15. Figure 2B does not show a dome, but a dome is equally relevant for this embodiment as for the embodiment of figure IB.

In a particularly designed version of the embodiment of Figures 2a and 2b, an umbilical with a split end (not shown) is used, allowing two tools 21 to be connected to and operated via one and the same umbilical. The split ends must each have a length allowing one tool be connected and launched at the time, or the connection and launching station 12 must be designed to accommodate two tools simultaneously.

Figure 3A is provides a simplified, schematic front view of a tool 21 positioned in a parking site comprising a pocket-like housing 111 supported by vertical bars 112 and a horizontal axis 113 about which the housing 111 may turn to an inclined angle. The tool part 21c that fits into the pocket-like housing 111 generally exhibits a surface element adapted to be releasably attached to a parking site of the subsea station (10) between operations. The one shown in Figure 3A is just an example. As an alternative, rather than shaping the entire "lower" part 21c of the tool 21 to fit a pocket-like housing 111, to provide each of the tools with a lateral extension (not shown) that fits into such a pocket-like housing, leaving the functional elements of the tools outside the pocket like housing. The advantage of that would be that the tools as such may be shaped with high degree of freedom with regard to size and shape, and that the pocket-like housing could be made comparatively small compared with the size of the tools.

Figure 3B shows same parking site in a side view, further illustrating that the housing 111 is held in an upright position with its back substantially parallel with the vertical bar 112 and releasably locked to the bar by simple snap-lock 114.

Figure 3C shows a position in which initiation of activation of the tool 21 has occurred. An activation member (not shown) from the connection and launching station has gripped a part of the tool 21 above the housing and pulls it towards the connection and launching station, thereby releasing the lock 114, allowing the housing 111 to turn forward along with the tool 21.

Now turning to Figure 3D, when a certain tilting angle has been reached, the tool 21 is pulled up and out from the housing 111 at an inclined angle, leaving the housing 111 empty in the inclined position.

Following this step, the tool 21 enters the connection and launching station, has its protective cap 21b over the interface 21a removed and the interface 15a of the umbilical connected thereto. All these steps may be handled by a PLC or similar computer device once the operator has instructed connection to be performed. The required accuracy for connection and disconnection of a tool is obtained by the system according to the present invention, mainly due to the overall compact structure and short distances between parking rack, connection and launching station, and the umbilical drum. The subsea station as described furthermore represents a robust system which ensures that the connection interfaces are clean at all times and therefore functions well overtime with minor maintenance interruptions. The procedure described above is reversed when a tool returns to the subsea station after having completed a task; the tool 21 enters the connection and launching station 12 , is disconnected from the umbilical 15, the protective cap 21b is put on and the tool 21 returned to the parking rack 11.

Figure 3E shows an embodiment that differs from the embodiments of Figures 3A-3D in that the tool part 21c' that fits into the pocket-like housing 111' is not part of the functional tool, but a separate protrusion or handle specifically made to fit the pocket-like housing 111' which allows the latter to be made much smaller than the pocket-like housing 111 shown in Figures 3A-3D.

Figure 4A shows schematically and simplified a side sectional view of part of a subsea station according to the present invention in a situation in which a tool 21 has been pulled into the connection and launching station 12 from the parking rack 11. The upper part 12a of the connection and launching station 12 is arranged to be filled with gas, such as nitrogen, at least during the operations described in Figures 4A - 4C, thereby preventing sea water from contacting the interfaces of the tool and the umbilical. An umbilical drum 14 is shown to the right with an umbilical 15 guided by guiding rolls 16a, 16b constituting parts of the guidance means 16, while the end of the umbilical is terminated by an umbilical interface 15a in the water-free zone 12a of the connection and launching station 12. The tool 21 exhibits a tool interface 21a and a protective cap 21b covering said interface. Figure 4A also shows a cap removing member 41 in the process of gripping the cap 21b in order to remove it, making the tool interface 21a accessible to the umbilical interface 15a. Any one of the guiding rolls 16a, 16b, may be tensioned by a spring or the like to ensure that the umbilical 15 is slightly tensioned at all times.

As an alternative to the arrangement of a water-free zone 12a, inductive connectors may be used for the interface between tool and umbilical, rendering such a water-free zone superfluous.

Figure 4B shows a situation in which the cap 21b has been removed from the tool 21 and moved sideways to make free passage for the umbilical interface 15a to the tool interface 21a.

Figure 4C shows a situation in which the umbilical interface 15a has been connected to the tool interface 21a by means of a connecting device 16c constituting another part of the guidance means 16 for the umbilical. The connecting device 16c, like the cap removing member 41 must be provided with energy from a source like an electric motor, not shown, and being capable of required mobility, such as linear and/ or pivotal movement.

Figure 4D shows the tool 21 being launched from the connection and launching station 12 by a downward movement caused by turning the umbilical drum 14 to unwind additional lengths of umbilical 15. Figure 5 shows different configurations of the parking rack, a linear rack 11a, a curved rack lib, and a rack 11c in the form of a matrix of rows and columns, as alternatives to the full circle arrangement shown in Figures 1 and 2.

It should be noted that the device according to the present invention, though designed to operate from a subsea location, also may be operated when connected to or carried by a floating vessel, in which the subsea station in practice is positioned wholly or partially above the sea surface.