Method of reconfiguring a subsea control module and associated subsea control module and subsea system

Abstract

The invention relates to a method of reconfiguring a subsea control module (100) connectable to a Xmas tree (11) of a subsea system (10) arranged at a seabed (1) surrounded by a body of water (3), wherein the subsea system (10) comprises a connection port (13';13'') and a fluid conduit (12';12''), wherein the connection port (13';13'') is in fluid communication with the fluid conduit (12';12''), and wherein the fluid conduit (12';12'') contains a first fluid with a first pressure (P1), wherein the subsea control module (100) comprises a return conduit (101) and a return port (102), the return port (102) opening directly or indirectly to the surrounding body of water (3), and wherein the method comprises the steps of: a) reconfiguring the return port (102) on a subsea control module (100';100''), wherein the return port (102) was originally designed for control fluid return to the body of water (3); b) providing a return conduit communication path (103) for fluid communication to the fluid conduit (12';12''), the return conduit communication path (103) comprising an intermediate fluid storage facility (105';105''). 20 The invention also relates to a subsea control module (100';100'') and a subsea system (10).

Description

[0001] METHOD OF RECONFIGURING A SUBSEA CONTROL MODULE AND ASSOCIATED SUBSEA CONTROL MODULE AND SUBSEA SYSTEM

[0002] Technical Field

[0003] The present disclosure relates to the technical field of subsea control modules (SCMs) connectable to subsea Xmas trees.

[0004] Background

[0005] The Subsea Control Module (SCM) contains electronics, control valves and internal transmitters for status monitoring. Each SCM continuously communicates with the topside Process Control System (PCS) - executing process valve operations on request and transmitting process and status data back. The normal location for the SCM's is one on each X-Mas tree. The number of controllable valves per subsea well is field specific, and varies among 6 and 16 typically - depending on the complexity of the subsea production system. In addition, remote instruments are hooked up to the SCM in service, from 3 to 10 per well typically. The SCM is an independently retrievable unit, i.e. it can be retrieved to a topside location independently the X-Mas tree it is connected to. SCMs are commonly used to provide well control functions during the production phase of subsea oil and gas production. Typical well control functions and monitoring provided by the SCM can be: fail-safe return X-Mas tree actuators, flow control choke valve operations, opening and closing shutoff valves, manifold diverter valves, chemical injection valves, downhole safety valves, downhole inflow control valves, reading of subsea and downhole pressure and temperature sensors, sand detectors, hydrocarbon leakage detectors, etc.

[0006] When controlling or operating the valves, it is common practice to use a water-based hydraulic fluid which is released to the surrounding seawater after valve operations. A complete subsea X-Mas tree operation requires 10-20 litres of hydraulic fluid, which may result in a yearly consumption of 1000-1500 litres per subsea well. This release to the surroundings is standard practice as the water-based hydraulic fluids are designed and approved for discharge.

[0007] However, due to changes in legislation, the suppliers of water-based hydraulic fluids experience an increasing challenge in finding chemicals approved for discharge, having sufficient rapid degradation, no bioaccumulation effects, and with low toxicity.

[0008] It is an objective of the invention to provide a solution with a reduced environmental impact.

[0009] Summary of the invention The present invention is directed to a solution that may solve or at least reduce at least one of the aforementioned problems or challenges and in particular in relation to avoid spent control fluid spill to sea.

[0010] The solution according to the invention solves the objective by reconfiguring a return port on the subsea control module such that the spent control fluid that normally would exit to sea through the return port is instead guided to a fluid conduit already present and available subsea.

[0011] The invention is defined in the attached claims.

[0012] The present invention relates to a method of reconfiguring a subsea control module connectable to a Xmas tree of a subsea system arranged at a seabed surrounded by a body of water, wherein the subsea system comprises a connection port and a fluid conduit, wherein the connection port is in fluid communication with the fluid conduit, and wherein the fluid conduit contains a first fluid with a first pressure, wherein the subsea control module comprises a return conduit and a return port, the return port opening directly or indirectly to the surrounding body of water, and wherein the method comprises the steps of: a) reconfiguring the return port on a subsea control module, wherein the return port was originally designed for control fluid return to the body of water; b) providing a return conduit communication path for fluid communication to the fluid conduit, the return conduit communication path comprising an intermediate fluid storage facility.

[0013] The present invention is particularly applicable for use in existing fields in operation, i.e. it involves reconfiguring a return port of a subsea control module, which return port was originally designed for control fluid return to the body of water, e.g. for releasing hydraulic fluid used when e.g. actuation a valve. According to the method, this fluid is exiting from the return conduit, through the reconfigured return port and to the return conduit communication path. The return conduit thus leads to the return port.

[0014] The return port of the subsea control module is reconfigured from an open solution to a closed loop solution. Closed loop shall be understood as instead of allowing spent control fluid to exit directly or indirectly to the surrounding body of water, the spent control fluid is collected in the intermediate fluid storage facility of the return conduit communication path.

[0015] Thus, the invention relates to reconfiguring or modifying the return port of a subsea control module which was previously installed on another Xmas tree, on the same Xmas tree or which has never been installed subsea. The connection port is available for the subsea control module in a way that the subsea control module can connect to the connection port, and thus the fluid conduit.

[0016] The return port is also denoted dump port. The purpose of the method is to reconfigure a return port on a subsea control module which return port was originally designed for control fluid return directly to sea. When arranging and using such a subsea control module with a reconfigured return port subsea, no return fluid is released to the surrounding body of water. The return port can be reconfigured either after retrieving the subsea control module as will be described in greater detail below, or it can be reconfigured using e.g. an ROV while the subsea control module is arranged subsea.

[0017] The fluid conduit forms part of the subsea system which is arranged outside of the subsea control module. Thus, the fluid conduit forms part of the subsea system which is already present subsea. The fluid conduit may lead to another location subsea, to shore or to a topside location.

[0018] The method may comprise, prior to step a), a step of retrieving the subsea control module from the subsea system.

[0019] The subsea control module may be either be retrieved to:

[0020] - a topside location such as a floating installation, a platform, a rig, etc,

[0021] - a subsea position, e.g. on to another subsea Xmas tree or on a seabed or a mudmat.

[0022] The subsea control module can thus be retrieved without retrieving the Xmas tree.

[0023] The return conduit communication path may also be denoted Dump fluid communication path. The return conduit communication path or dump fluid communication path may be a return conduit communication conduit.

[0024] The intermediate fluid storage facility is configured to receive spent control fluid from operation of a subsea device, such as e.g. an actuator. The volume of such an operation is of the order of magnitude 10-20 litres per full XT operation. Thus, the intermediate fluid storage facility is of sufficient volume to receive the amount of control fluid used in one operation.

[0025] The intermediate fluid storage facility may be a tank, a bladder or a piston arc. Alternatively, the intermediate fluid storage facility may be a pipe section.

[0026] The source for the control fluid entering the subsea control module may be an umbilical or other fluid supply line known to the person skilled in the art.

[0027] Preferably, step b) comprises connecting the return conduit communication path to the return port. The method may comprise a step: c) lowering and installing the subsea control module which has a reconfigured return port on the subsea system at the seabed.

[0028] Step a) may comprise plugging the return port.

[0029] The fluid conduit may contain a first fluid with a first pressure and the method may comprise a step of: d) providing a pressure boosting device in the return conduit communication path, where the pressure boosting device is configured to increase a pressure of a second fluid contained in the return conduit communication path and the intermediate fluid storage facility to a second pressure, where the second pressure is higher than the first pressure such that the second fluid flows into the fluid conduit via the connection port.

[0030] The pressure boosting device is preferably arranged downstream of the intermediate fluid storage facility.

[0031] The pressure boosting device is configured to assist in evacuating the second fluid contained in the return conduit communication path and / or in the intermediate fluid storage facility by increasing the pressure of the second fluid a pressure which is higher than the first pressure of the first fluid conduit contained in the fluid conduit.

[0032] The method may comprise the steps of:

[0033] - providing an increased volume inside the subsea control module; and

[0034] - arranging the intermediate fluid storage facility inside the increased volume of the subsea control module.

[0035] Alternatively, if there is available volume inside the SCM, the intermediate fluid storage facility may be positioned inside the available volume. I.e., in this latter example, the step of providing an increased volume inside the subsea control module is not required.

[0036] The method may comprise:

[0037] - arranging the pressure boosting device inside the increased volume of the subsea control module.

[0038] The method may comprise:

[0039] - arranging the intermediate fluid storage facility outside of the subsea control module.

[0040] For example, if the return port is reconfigured while the subsea control module is arranged subsea, the intermediate fluid storage facility has to be outside the subsea control module.

[0041] The method may comprise:

[0042] - arranging the pressure boosting device outside of the subsea control module. The pressure boosting device may be an active receiver. The active receiver can for example be the device controlling a hydraulic actuator in a subsea system as described in W02001023702A1 (applicant: Kongsberg Offshore AS).

[0043] The method may comprise fluidly connecting one side of the active receiver to the return conduit communication path and another side to the fluid conduit in the form of a low pressure supply line.

[0044] The pressure boosting device may be a pump.

[0045] The Xmas tree may comprise a Multi-Quick Connect interface, and the Multi-Quick Connect interface may comprise the connection port, and the subsea control module may comprise a subsea control module mounting base (SCMMB) of a complementary shape to the Multi-Quick Connect interface, and the method may comprise the steps of: cl) connecting the return conduit communication path to a fluid line of the MultiQuick Connect plate, where said fluid line is connectable to the connection port of the Multi-Quick Connect interface, and c2) connecting the Multi-Quick Connect plate to the Multi-Quick Connect interface.

[0046] The fluid conduit may be a supply line for control fluid into the subsea control module. Spent control fluid may then exit through the subsea control module mounting base (SCMMB), the MQC interface and into the supply line for control fluid into the subsea control module. Since the pressure in this supply line is larger than the pressure in the intermediate fluid storage facility, the pressure boosting device is required in order to evacuate or release the spent control fluid to the supply line.

[0047] The return conduit communication path may extend out from a side or a top of the subsea control module, and the method may comprise: connecting the return conduit communication path to the connection port.

[0048] The fluid conduit may be an annulus bleed or a service line.

[0049] The fluid conduit may be an injection line, such as e.g. a chemical injection line. The chemical injection line may be a glycol injection which may be especially well suited since waterbased control fluids contain a large portion of glycol.

[0050] In the event the fluid conduit is the annulus bleed line or a service line, it may not be required to have a pressure boosting device since the pressure in these lines are normally lower than the pressure in the intermediate fluid storage facility. Furthermore, the intermediate fluid storage facility may also not be required, since the fluid can be vented directly to the fluid conduit. However, if the pressure in these lines is larger than the pressure in the intermediate fluid storage facility, a pressure boosting device may be required in order to evacuate or release the spent control fluid to the annulus bleed line or the service line. The fluid conduit may be the main (hydrocarbon) production line.

[0051] The fluid conduit may be a spare line. The spare line may e.g. be an available spare line in an umbilical (if an umbilical is used).

[0052] Since the pressure in this injection line is normally larger than the pressure in the intermediate fluid storage facility, the pressure boosting device is required in order to evacuate or release the spent control fluid to the injection fluid line.

[0053] Regardless whether the fluid conduit is an annulus bleed line, a service line, an injection fluid line, the main production line and / or a supply line, it may be connected to the return conduit communication path via the connection port. There are several alternatives for this connection, every subsea make / break fluid connection with a fluid continuing to surface can in principle be used.

[0054] Many subsea systems have “logic caps” installed on the XTs or manifolds. These are fluid connection MQC plates with typically 12-13 individual fluid connectors. Fluids are looped in and out of the MQC plate cap (logic cap). If needed, the logic cap can be replaced with another cap with a different routing of the fluids. For instance, the logic cap can connect the return fluid connection to the service line. If the return fluid connection service line is not already one of the fluid paths through the logic cap, it can be connected to the logic cap via a hose from the top or side of the SCM.

[0055] Many subsea systems have spare MQC plates for external connection to future wells, these may have access for the return fluid and supply fluids and can be connected as described above.

[0056] Thus, the connection port in a Logic cap is accessible. It may also be possible to connect to another available fluid line, provided that this available fluid line is accessible and can function as a return or dump for the spent control fluid. In either case, the available fluid line has another initial function different from serving as a connection point for the return conduit communication path.

[0057] Other possible connection points could be:

[0058] Fluid sampling points

[0059] Between outboard and inboard hubs, for instance via the seal plate retrieved and modified to include a hose with connection to the top / side of the SCM

[0060] Tree cap, retrieved and modified to include a hose with connection to the top / side of the SCM.

[0061] The subsea control module which is reconfigured in step a) may be a different subsea control module than the subsea control module which is retrieved. The subsea control module which is reconfigured is preferably another subsea control module than the one which is retrieved. This is due to that the operator wants to change the subsea control module in one operation in order to minimize downtime in the production from the Xmas tree. The subsea control module which is reconfigured is a subsea control module which initially had a return port directly or indirectly to sea. This subsea control module has formed part of a subsea system and then been retrieved and reconfigured. Alternatively, this subsea control module is a new subsea control module originally designed for control fluid return to sea.

[0062] The subsea control module which is reconfigured in step a) may be the same subsea control module as the subsea control module which is retrieved.

[0063] The present invention also relates to a subsea control module connectable to a Xmas tree of a subsea system arranged at a seabed surrounded by a body of water, wherein the subsea system comprises a connection port and a fluid conduit, wherein the connection port is in fluid communication with the fluid conduit, wherein the subsea control module comprises:

[0064] - a return conduit and a reconfigured return port which was originally designed for control fluid return directly or indirectly to the body of water,

[0065] - a return conduit communication path for fluid communication to the fluid conduit, the return conduit communication path comprising an intermediate fluid storage facility.

[0066] The fluid conduit may contain a first fluid with a first pressure, and the subsea system may comprise a pressure boosting device in the return conduit communication path, where the pressure boosting device may be configured to increase a pressure of a second fluid contained in the return conduit communication path and the intermediate fluid storage facility to a second pressure, where the second pressure is higher than the first pressure such that the second fluid flows into the fluid conduit via the connection port.

[0067] The pressure boosting device is preferably arranged downstream of the intermediate fluid storage facility.

[0068] The pressure boosting device is configured to assist in evacuating the second fluid contained in the return conduit communication path and / or in the intermediate fluid storage facility by increasing the pressure of the second fluid to a pressure which is higher than the first pressure of the first fluid conduit contained in the fluid conduit.

[0069] The intermediate fluid storage facility may be arranged inside the subsea control module.

[0070] The pressure boosting device may be arranged inside the subsea control module.

[0071] The intermediate fluid storage facility and pressure boosting device may not be required if the pressure in the fluid conduit is lower than the pressure in the return conduit communication path. The present invention also relates to a subsea system arranged at a seabed surrounded by a body of water, the subsea system comprises:

[0072] - a subsea control module as described above;

[0073] - a Xmas tree;

[0074] - a connection port;

[0075] - a fluid conduit in fluid communication with the connection port.

[0076] Above-discussed preferred and / or optional features of each aspect of the invention may be used, alone or in appropriate combination, in the other aspects of the invention.

[0077] The claimed invention is specified in the independent claims of this application. Advantageous adaptations and versions of the claimed invention are specified in the independent claims.

[0078] Description of the drawings

[0079] Following drawings are appended to facilitate the understanding of the claimed invention:

[0080] Fig. 1A shows a setup of a subsea system according to prior art;

[0081] Fig. IB shows more details of the subsea system of Fig. 1A, including the subsea control module with a return conduit connected to a return port of the subsea control module designed for control fluid return to the body of water;

[0082] Fig. 1C is an example of a hydraulic schematic of a prior art subsea control module operating a subsea device in the form of an actuator, where the subsea control module comprises a directional control valve operating the actuator, where the directional control valve is in a first position where the actuator is not in communication with a supply line and the control fluid is allowed to flow from a first chamber arranged on one side of a piston of the actuator, to a second chamber on an opposite side of the piston in the actuator, via the directional control valve;

[0083] Fig. ID is the prior art hydraulic schematic of Fig. 1C, where the directional control valve is in a second position where the actuator is in communication with the supply line and control fluid is prevented to flow from the first chamber arranged on one side of the piston of the actuator, and to the second chamber on the opposite side of the piston in the actuator;

[0084] Fig. 2A shows a subsea system with a subsea control module with a reconfigured return port, where the return port is in fluid communication with a fluid conduit via a Control module base plate;

[0085] Fig 2B is a hydraulic schematic of the subsea control module connected to a Xmas tree as shown in Fig. 2C, the connection to the Xmas tree being via a subsea control module mounting base; Fig. 2C shows the same subsea system as Fig. 2A with the exception that the subsea system in Fig. 2C features a pressure boosting device in the form of a pressure boosting device in the return conduit communication path;

[0086] Fig. 2D is a hydraulic schematic of the subsea control module connected to a Xmas tree as shown in Fig. 2C, the connection to the Xmas tree being via a subsea control module mounting base;

[0087] Fig. 3A shows a subsea system with a subsea control module with a reconfigured return port, where a return conduit communication path extends from the reconfigured return port out from a side or a top of the subsea control module;

[0088] Fig. 3B shows the same subsea system as Fig. 3A with the exception that the subsea system in Fig. 3B features a pressure boosting device in the return conduit communication path inside a volume of the subsea control module;

[0089] Fig. 3C shows the same subsea system as Fig. 3B with the exception that the subsea system in Fig. 3C features a pressure boosting device and an intermediate fluid storage facility in the return conduit communication path outside a volume of the subsea control module;

[0090] Fig. 3D is a schematic view of the subsea system in Fig. 3C including hydraulic lines;

[0091] Fig. 4 is a hydraulic schematic of a subsea system featuring a subsea control module with a reconfigured return port, an intermediate fluid storage facility in the form of an active receiver with built in fluid storage in a return conduit communication path connected to a fluid conduit in the form of a supply line inside the subsea control module;

[0092] Fig. 5 is a hydraulic scheme 10 of a subsea system featuring a subsea control module with a reconfigured return port, an intermediate fluid storage facility in the form of a tank and a pressure boosting device in a return conduit communication path connected to a fluid conduit in the form of a supply line outside the subsea control module, where the return conduit communication path is connected to the supply line via a modified outboard Multi-Quick Connect (MQC) plate on an umbilical / umbilical termination assembly;

[0093] Fig. 6 is a hydraulic scheme of a subsea system featuring a subsea control module with a reconfigured return port, an intermediate fluid storage facility in the form of a tank and a pressure boosting device in a return conduit communication path which is connected to a workover logic cap;

[0094] It should be understood, however, that the drawings are not intended to limit the claimed invention to the subject-matter depicted in the drawings. In the drawings, like reference numerals have been used to indicate common parts, elements or features unless otherwise explicitly stated or implicitly understood by the context.

[0095] Detailed description

[0096] In the following, one or more specific embodiments of the invention will be described in more detail with reference to the drawings. However, it is specifically intended that the invention is not limited to the embodiments and illustrations contained herein but includes modified forms of the embodiments including portions of the embodiments and combinations of elements of different embodiments as come within the scope of the following claims. It should be appreciated that in the development of any such actual implementation, as in any engineering or design project, numerous implementationspecific decisions must be made to achieve the developer’s specific goals, such as compliance with system and / or business-related constraints, which may vary from one implementation of the invention to another. Moreover, it should be appreciated that such a development effort might be complex and time consuming, but would nevertheless be a routine undertaking of design, fabrication and manufacture for the skilled person having the benefit of this disclosure.

[0097] Fig. 1A shows a setup of a subsea system 10 according to prior art. The subsea system 10 is arranged on a seabed 1 and surrounded by a body of water 3. The subsea system 10 features an umbilical 5 terminating at a topside location 2 in a first end and to a subsea distribution unit 4 in a second end. The subsea distribution unit 4 is connected to a Xmas tree 11 via hydraulic / chemical jumpers 6 and electrical jumpers 7. A retrievable prior art subsea control module (SCM) 100 with a control fluid return to the body of water is connected to the Xmas tree 11.

[0098] At the topside location 2, the umbilical 5 is in communication with a chemical injection line 21, a hydraulic power unit 22, a topside gateway 24 via a master control system 25 and an electric power unit 26.

[0099] It is also disclosed a typical cross section of the umbilical 5.

[0100] Fig. IB shows more details of the subsea system 10 of Fig. 1A, including the subsea control module 100 with a return conduit 101 connected to a return port 102 of the subsea control module 100. The return port 102 in Fig. IB is designed for control fluid return to the body of water 3.

[0101] A fluid conduit 12 extends from the Xmas tree 11. The topside installation 2 in Fig. IB is a floating installation 2 which floats at the surface 8 of the body of water 3. A fluid conduit 12, e.g. an annulus bleed line or a service line, extends from the Xmas tree 11 to the topside installation 2. Fig. 1C is an example of a hydraulic schematic of a prior art subsea control module 100 operating a subsea device in the form of an actuator 40, where the subsea control module 100 comprises a directional control valve (DCV) 30 operating the actuator 40. In Fig. 1C, the directional control valve 30 is in a first position where the actuator 40 is not in communication with a supply line 15,16 (which can be a low pressure supply line 15 or a high pressure supply line 16) and the control fluid is allowed to flow from a first chamber 41 arranged on one side of a piston 42 of the actuator 40, to a second chamber 43 on an opposite side of the piston 42 in the actuator 40, via inlet line 55, the directional control valve 30 and return line 56. A spring 44 is arranged in the second chamber 43 biasing the piston 42 towards the first chamber (i.e. towards left in Fig. 1C).

[0102] The dotted line 100 illustrates the subsea control module 100, i.e. the components arranged inside the dotted line 100 form part of the subsea control module 100.

[0103] The subsea control module 100 features a subsea control module mounting base (SCMMB) 106 for connecting to the subsea control module 100 to the interface on e.g. a Xmas tree 11. In the illustrated example, the SCMMB 106 features three one-way valves 50’, 50”, 50”’ for connection to the interface. Similarly, the interface features three complementary one-way valves 51’, 51”, 51’” for connection to the SCMMB 106. When the subsea control module 100 is connected to the interface on e.g. the Xmas tree 11, all of the three oppositely directed one-way valves 50’, 50”, 50’”; 51’, 51”, 51”’ are in an open position providing fluid flow therethrough.

[0104] Fig. ID is the prior art hydraulic schematic of Fig. 1C, where the directional control valve 30 is in a second position where the actuator 40 is in communication with the supply line 15,16 and control fluid is prevented to flow from the first chamber 41 arranged on one side of the piston 42 in the actuator 40, and to the second chamber 43 on the opposite side of the piston 42 in the actuator 40.

[0105] The inlet line 55 connects the first chamber 41 of the actuator 40 to the directional control valve 30 and the return line 56 connects the second chamber 43 of the actuator 40 to the directional control valve 30.

[0106] With reference to Figs. 1C and ID, a typical sequence of operating the actuator 40 will be described. When comparing the relative positions of the piston 42 in the actuator 40 in Figs. 1C and ID, it is apparent that the piston has moved towards the right in Fig. ID compressing the spring 44.

[0107] In Fig. 1C the directional control valve 30 is in the first position shutting off the supply line 15,16 and allowing the first chamber 41 and the second chamber 43 to be in fluid communication via the inlet line 55, the directional control valve 30 and the return line 56, such that the pressure in both chambers 41, 43 are equal. The only force working on the piston is the spring force from the spring 44 which biases the piston 42 towards the first chamber 41. All of the inlet line 55, the first chamber 41, the return line 56, the second chamber 43 and return line 56 is filled with control fluid at equal pressure (i.e. the same pressure).

[0108] When moving the directional control valve 30 to the second position (ref. Fig. ID), control fluid from the supply line 15,16 enters into the first chamber 41 via the directional control valve 30 and the inlet line 55. The pressure of this control fluid is larger than the pressure in the second chamber 43 (including the spring force of the spring 44) resulting in that the piston 42 moves toward the second chamber 43. The control fluid which was present in the second chamber 43 is forced out through the return line 56 and exits through the return conduit 101 and return port 102 to the surrounding body of water.

[0109] When moving from the state in Fig. ID to the state in Fig. 1C, the directional control valve 30 moves from the second position to the first position. Control fluid which was present in the first chamber 41 is forced out by the spring force of the spring 44 in the second chamber 43 and into the inlet line 55 and further to the return line 56 and into the second chamber 43 until the pressure of the control fluid has been equalized in the first and second chambers 41,43.

[0110] In the following, the functioning of the directional control valve 30 and the actuator 40 are identical for all of the example subsea systems 10 in the following Figs. 2-6 as described in relation to Figs 1C and ID.

[0111] Fig. 2A shows a subsea system 10 with a subsea control module 100’ with a reconfigured return port 102, and a return conduit 101 connected to the return port 102. The return port 102 is in fluid communication with a fluid conduit 12’ via a Control module base plate (not shown in Fig. 2A, see Figs. 5 A and 5C). The subsea control module 100’ features a return conduit communication path 103 for fluid communication to the fluid conduit 12’. The return conduit communication path 103 comprising an intermediate fluid storage facility 105’ for collecting spent control fluid from operation of a subsea device, such as an actuator 40. The volume of such an operation is in the order of magnitude 10-20 litres per operation. Thus, the intermediate fluid storage facility 105’ is of sufficient volume to receive the amount of control fluid used in one operation.

[0112] The Control module base plate is fitted with multiple couplers that enable transfer of fluids between subsea systems such as trees and manifolds. The control module 100’ typically features a subsea control module mounting base (SCMMB) 106. The control module base plate 106 is connectable to e.g. Multi-Quick Connect interface of the Xmas tree 11. The Multi-Quick Connect interface comprises the connection port 13’. The connection port 13’ is in fluid communication with the fluid conduit 12’. The connection port 13’ is thus available for the subsea control module 100’ in a way that the subsea control module 100’ can connect to the connection port 13’, and thus the fluid conduit The fluid conduit 12’ forms part of the subsea system 10 which is arranged outside of the subsea control module 100’. Thus, the fluid conduit 12’ forms part of the subsea system 10 which is already present subsea. The fluid conduit 12’ may lead to another location subsea, to shore or to a topside location (e.g. as descried in relation to Figs. 1A and IB).

[0113] The fluid conduit 12’ contains a first fluid with a first pressure Pl . If the pressure of a second fluid (i.e. the spent control fluid) contained in the return conduit communication path 103 and the intermediate fluid storage facility 105’ is higher than the first pressure Pl of the first fluid, the second fluid will flow towards, and into, the fluid conduit 12’.

[0114] Fig. 2B is a hydraulic schematic of the subsea control module 100’ connected to a Xmas tree 11 as shown in Fig. 2A, the connection to the Xmas tree 11 being via a subsea control module mounting base 106. The functioning and the components in the hydraulic scheme, except for the return port 102, is similar to the one described in relation to Figs. 1C and ID and will not be repeated herein. When comparing with prior art of Figs. 1C and ID, the return port in Fig. 2B has been reconfigured from control fluid return to the surrounding body of water 3 to guide the control fluid to a return conduit communication path 103. The return conduit communication path 103 comprises an intermediate fluid storage facility 105’ and is connected to the connection port 13’ in the subsea control module mounting base 106.

[0115] Fig. 2C shows the same subsea system 10 as Fig. 2A with the exception that the subsea system 10 in Fig. 2C features a pressure boosting device 104 in the form of a pressure boosting device 104 in the return conduit communication path 103. The pressure boosting device 104 is configured to increase a pressure of the second fluid contained in the return conduit communication path 103 and the intermediate fluid storage facility 105’ to a second pressure P2 which is higher than the first pressure Pl in the fluid conduit 12’. This may be necessary if the first pressure Pl is higher than the pressure in the return conduit communication path 103 and the intermediate fluid storage facility 105’ in order for the second fluid in the return conduit communication path 103 to flow into the fluid conduit 12’ via the connection port 13’.

[0116] Fig. 2D is a hydraulic scheme of the subsea control module 100’ connected to a Xmas tree 11 as shown in Fig. 2C, the connection to the Xmas tree 11 being via a subsea control module mounting base 106. The functioning and the components in the hydraulic scheme, except for the return port 102, is similar to the one described in relation to Figs. 1C and ID and will not be repeated herein. When comparing with prior art of Figs 1C and ID, the return port in Fig. 2B has been reconfigured from control fluid return to the surrounding body of water 3 to guide the control fluid to a return conduit communication path 103. The return conduit communication path 103 comprises an intermediate fluid storage facility 105’ and a pressure boosting device 104.

[0117] Fig. 3 A shows a subsea system 10 with a subsea control module 100” with a reconfigured return port 102, and a return conduit 101 connected to the return port 102. The return port 102 is in fluid communication with a fluid conduit 12” via a return conduit communication path 103. The return conduit communication path 103 extends from the reconfigured return port 102 in an upper end or top of the subsea control module 100”, to a connection port 13” of the fluid conduit 12”.

[0118] The return conduit communication path 103 comprising an intermediate fluid storage facility 105’ for collecting spent control fluid from operation of the subsea device (i.e. actuator 40) as described in relation to Fig. 2A.

[0119] The fluid conduit 12” forms part of the subsea system 10 which is arranged outside of the subsea control module 100”. Thus, the fluid conduit 12” forms part of the subsea system 10 which is already present subsea. The fluid conduit 12” may lead to another location subsea, to shore or to a topside location (e.g. as descried in relation to Figs. 1A and IB).

[0120] The fluid conduit 12” contains a first fluid with a first pressure Pl. If the pressure of a second fluid (i.e. the spent control fluid) contained in the return conduit communication path 103 and the intermediate fluid storage facility 105’ is higher than the first pressure Pl of the first fluid, the second fluid will flow towards, and into, the fluid conduit 12’.

[0121] Fig. 3B shows the same subsea system as Fig. 3A with the exception that the subsea system 10 in Fig. 3B features a pressure boosting device 104 in the return conduit communication path 103 inside a volume of the subsea control module 100”. The pressure boosting device 104 is configured to increase a pressure of the second fluid contained in the return conduit communication path 103 and the intermediate fluid storage facility 105’ to a second pressure P2 which is higher than the first pressure Pl in the fluid conduit 12”. This may be necessary if the first pressure Pl is higher than the pressure in the return conduit communication path 103 and the intermediate fluid storage facility 105’ in order for the second fluid to flow into the fluid conduit 12” via the connection port 13”.

[0122] Fig. 3C shows the same subsea system 10 as Fig. 3B with the exception that the subsea system 10 in Fig. 3C features a pressure boosting device 104 and an intermediate fluid storage facility 105 in the return conduit communication path outside a volume of the subsea control module 100”.

[0123] Fig. 3D is a schematic view of the subsea system 10 in Fig. 3C including hydraulic lines.

[0124] Instead of arranging the intermediate fluid storage facility 105” (and the pressure boosting device 104) outside of the subsea control module 100”, either the intermediate fluid storage facility 105” and / or the pressure boosting device 104 could be arranged inside the subsea control module as discussed above e.g. in relation to Figs. 2B and 2D.

[0125] Fig. 4 is a hydraulic schematic of a subsea system 10 featuring a subsea control module 100’, 100” with a reconfigured return port 102 and a pressure boosting device in the form of an active receiver 121 in the return conduit communication path 103 connected to a fluid conduit 12’ in the form of a low pressure supply line 15 inside the subsea control module 100’, 100”. The subsea system 10 features an umbilical termination assembly 9 with a number of lines, including a Low pressure (LP) supply line 15, a High pressure (HP) 16 supply line and a return conduit line 107. The Low pressure (LP) supply line 15 contains a first fluid having a first pressure PL

[0126] The return conduit communication path 103 comprising an intermediate fluid storage facility 105” in the form of a tank. The intermediate fluid storage facility 105” being arranged inside the subsea control module 100’, 100”.

[0127] The subsea system 10 comprises a logic cap 120 capping off the original return port such that the return control fluid exits through the reconfigured return port 102.

[0128] The active receiver 121 serves as a temporary storage for return control fluid from operation of the Xmas tree (in closed hydraulic circuits). The Active receiver 121 maintains the pressure of a second fluid in the return conduit communication path 103 at a second pressure P2 which is higher than the first pressure Pl such that the second fluid will flow towards, and into, the Low pressure (LP) supply line 15. 1.e. the active receiver 121 receives return control fluid from the return conduit communication path 103, temporary stores the received fluid, and force it into the low pressure supply line 15 (which can be e.g. in an umbilical) over an extended period of time. The temporary storage of return fluid in the active receiver 121 reduces the required return line ID for the backflow fluid. The active receiver 121 is therefore a hydraulic economical solution when using a closed loop system. As mentioned above, the active receiver can be the device controlling a hydraulic actuator in a subsea system as described in W02001023702A1 (applicant: Kongsberg Offshore AS).

[0129] Fig. 5 is a hydraulic scheme of a subsea system 10 featuring a subsea control module 100 ’,100” with a reconfigured return port 102, an intermediate fluid storage facility 105” in the form of a tank and a pressure boosting device 104 in a return conduit communication path connected to a fluid conduit in the form of a supply line 12”, 15 outside the subsea control module 100’, 100”, where the return conduit communication path 103 is connected to the supply line 15 via a modified outboard Multi-Quick Connect (MQC) plate on an umbilical 5 / umbilical termination assembly 9.

[0130] As described in relation to Fig. 3A, if the pressure in the second fluid (i.e. the spent control fluid) contained in the return conduit communication path 103 and the intermediate fluid storage facility 105’ is higher than the first pressure Pl of the first fluid in the supply line 12’, 15, the pressure boosting device 104 (e.g. the active receiver 121) may not be required.

[0131] Fig. 6 is a hydraulic scheme of a subsea system 10 featuring a subsea control module 100’, 100” with a reconfigured return port 102, an intermediate fluid storage facility 105’ in the form of a tank and a pressure boosting device in a return conduit communication path 103 which is connected to a workover logic cap 120.

[0132] The supply line 12”, 15 into the subsea control module 100’, 100” is shown as being connected to a supply line in the logic cap 120. However, it is possible that the supply line 12” is fed from another subsea location.

[0133] Although all of the examples in Figs. 4-6 features a pressure boosting device 104 (e.g. active receiver 121), this may not be required if the pressure in the second fluid (i.e. the spent control fluid) contained in the return conduit communication path 103 and the intermediate fluid storage facility 105’ is higher than the first pressure Pl of the first fluid in the supply line 12’, 15 (as described in relation to Fig. 3 A).

[0134] In all of the exemplified embodiments in Figs. 2-6, at least one fluid conduit 12’, 12” is available for connection jo the return conduit communication path 103 such that control fluid flowing through the return conduit 101 into the reconfigured return port 102 can flow from the return port 102, via the return conduit communication path 103 with intermediate fluid storage facility 105’, 105”, to the connection port 13’, 13” and into the fluid conduit 12’, 12”.

[0135] In the preceding description, various aspects of the system, method and control module according to the invention have been described with reference to the illustrative embodiment. For purposes of explanation, specific numbers, systems and configurations were set forth in order to provide a thorough understanding of the system, method and control module and its workings. However, this description is not intended to be construed in a limiting sense. Various modifications and variations of the illustrative embodiment, as well as other embodiments, which are apparent to person skilled in the art to which the disclosed subject-matter pertains, are deemed to lie within the scope of the present invention as defined by the following claims.

[0136] LIST OF REFERENCE NUMBERS

[0137] 1 Seabed

[0138] 2 Topside location / topside installation

[0139] 3 Body of water

[0140] 4 Subsea distribution unit

[0141] 5 Umbilical

[0142] 6 Hydraulic / Chemical jumper

[0143] 7 Electrical jumpers

[0144] 8 Surface of body of water

[0145] 9 Umbilical Termination Assembly

[0146] 10 Subsea system

[0147] 11 XT / Xmas tree

[0148] 12, 12’, 12” Fluid conduit

[0149] 13 ’ , 13 ” Connection port

[0150] 15 Low pressure (LP) supply line

[0151] 16 High pressure (HP) supply line

[0152] 17 Accumulator

[0153] 21 Chemical injection line

[0154] 22 Hydraulic power unit (HPU)

[0155] 24 Topside gateway

[0156] 25 Master control system

[0157] 26 Electric power unit

[0158] 30 Directional control valve (DCV)

[0159] 40 Actuator

[0160] 41 First chamber

[0161] 42 Piston

[0162] 43 Second chamber

[0163] 44 Spring

[0164] 50’, 50”, 50’” One-way valve on SCMMB 106

[0165] 51’, 51 ”, 51 ’” One-way valve on interface (e.g. Xmas tree)

[0166] 55 Inlet line

[0167] 56 Return line

[0168] 100 Prior art Subsea Control Module (SCM) with original return port

[0169] 100’;100” Subsea Control Module (SCM) with reconfigured return port

[0170] 101 Return conduit / Dump conduit

[0171] 102 Return port / Dump port

[0172] 103 Return conduit communication path / Dump conduit communication path

[0173] 104 Pressure boosting device

[0174] 105 ’ , 105 ” Intermediate fluid storage facility

[0175] 106 Subsea control module mounting base (SCMMB)

[0176] 107 Return conduit line

Claims

Claims1. A method of reconfiguring a subsea control module (100) connectable to a Xmas tree (11) of a subsea system (10) arranged at a seabed (1) surrounded by a body of water (3), wherein the subsea system (10) comprises a connection port (13 ’ ; 13 ”) and a fluid conduit (12’ ; 12”), wherein the connection port (13 ’ ; 13 ”) is in fluid communication with the fluid conduit (12’; 12”), and wherein the fluid conduit (12’; 12”) contains a first fluid with a first pressure (Pl), wherein the subsea control module (100) comprises a return conduit (101) and a return port (102), the return port (102) opening directly or indirectly to the surrounding body of water (3), and wherein the method comprises the steps of: a) reconfiguring the return port (102) on a subsea control module (100’; 100”), wherein the return port (102) was originally designed for control fluid return to the body of water (3); b) providing a return conduit communication path (103) for fluid communication to the fluid conduit (12’; 12”), the return conduit communication path (103) comprising an intermediate fluid storage facility (105’;105”).

2. The method according to claim 1, comprising, prior to step a), a step of retrieving the subsea control module (100’;100”) from the subsea system (10).

3. The method according to claim 2, wherein the method comprises a step: c) lowering and installing the subsea control module (100’; 100’) which has a reconfigured return port (102) on the subsea system (10) at the seabed (1).

4. The method according to any of the preceding claims, wherein step a) comprises plugging the return port (102).

5. The method according to any of the preceding claims, wherein the fluid conduit (12’; 12”) contains a first fluid with a first pressure (Pl) and wherein the method comprises a step of: d) providing a pressure boosting device (104) in the return conduit communication path (103), wherein the pressure boosting device (104) is configured to increase a pressure of a second fluid contained in the return conduit communication path (103) and the intermediate fluid storage facility (105 ’ ; 105 ”) to a second pressure (P2), wherein the second pressure (P2) is higher than the firstpressure (Pl) such that the second fluid flows into the fluid conduit (12’; 12”) via the connection port (13 ’ ; 13 ”).

6. The method according to any of the preceding claims, wherein the method comprises the steps of:- providing an increased volume inside the subsea control module (100’;100”); and- arranging the intermediate fluid storage facility (105’; 105”) inside the increased volume of the subsea control module (100’;100”).

7. The method according to claim 6, when dependent upon claim 5, wherein the method comprises:- arranging the pressure boosting device (104) inside the increased volume of the subsea control module (100’;100”).

8. The method according to any of the preceding claims 1-5, wherein the method comprises:- arranging the intermediate fluid storage facility (105”) outside of the subsea control module (100’; 100”).

9. The method according to claim 5, or claim 8 when dependent upon claim 5, wherein the method comprises:- arranging the pressure boosting device (104) outside of the subsea control module (100’;100”).

10. The method according to claim 5, 7 or 9, or claim 6 or 8 when dependent on claim 5, wherein the pressure boosting device (104) is an active receiver (121).

11. The method according to any of the preceding claims claim 5, 7 or 9, or claim 6 or 8 when dependent on claim 5, wherein the pressure boosting device (104) is a pump (104).

12. The method according to any of the preceding claims 3-11, wherein the Xmas tree (11) comprises a Multi-Quick Connect interface, and wherein the MultiQuick Connect interface comprises the connection port (13’), and wherein the subsea control module (100’) comprises a subsea control module mounting base (06) of a complementary shape to the Multi-Quick Connect interface, and wherein the method comprises the steps of: cl) connecting the return conduit communication path (103) to a fluid line of the subsea control module mounting base (106), wherein said fluid line is connectable to the connection port (13’) of the Multi-Quick Connect interface, andc2) connecting the subsea control module mounting base (106) to the MultiQuick Connect interface.

13. The method according to claim 12 when dependent upon claim 5, wherein the fluid conduit (12’) is a supply line for control fluid into the subsea control module (100’;100”).

14. The method according to any of the preceding claims 1-11, wherein the return conduit communication path (103) extends out from a side or a top of the subsea control module (100”), and wherein the method comprises:- connecting the return conduit communication path (103) to the connection port (13’;13”).

15. The method according to claim 14, wherein the fluid conduit (12”) is an annulus bleed line (12”), a service line (12”) or an injection fluid line (12”).

16. The method according to any of the preceding claims 2-15, wherein the subsea control module (100’; 100”) which is reconfigured in step a) is a different subsea control module than the subsea control module (100) which is retrieved.

17. The method according to any of the preceding claims 2-15, wherein the subsea control module (100’; 100”) which is reconfigured is the same subsea control module as the subsea control module (100) which is retrieved.

18. A subsea control module (100’; 100”) connectable to a Xmas tree (11) of a subsea system (10) arranged at a seabed (1) surrounded by a body of water (3), wherein the subsea system (10) comprises a connection port (13 ’; 13 ”) and a fluid conduit (12’ ; 12”), wherein the connection port (13 ’ ; 13 ”) is in fluid communication with the fluid conduit (12’; 12”), wherein the subsea control module (100’ ; 100”) comprises:- a return conduit (101) and a reconfigured return port (102) which was originally designed for control fluid return directly or indirectly to the body of water (3),- a return conduit communication path (103) for fluid communication to the fluid conduit (12’;12”), the return conduit communication path (103) comprising an intermediate fluid storage facility (105).

19. The subsea control module (100’ ; 100”) according to claim 18, wherein the fluid conduit (12’;12”) contains a first fluid with a first pressure (Pl), and wherein the subsea system (10) comprises a pressure boosting device (104) in the return conduit communication path (103), wherein the pressure boosting device (104) is configured to increase a pressure of a second fluid contained in the return conduit communication path (103) and the intermediate fluid storage facility (105) to a second pressure (P2), wherein the second pressure (P2) is higher than the firstpressure (Pl) such that the second fluid flows into the fluid conduit (12’; 12”) via the connection port (13 ’ ; 13 ”).

20. The subsea control module (100’;100”) according to claim 18 or 19, wherein the intermediate fluid storage facility (105) is arranged inside the subsea control module (100’;100”).

21. The subsea control module (100’;100”) according to any of the preceding claims 18-20, wherein the pressure boosting device is arranged inside the subsea control module (100’;100”).

22. A subsea system (10) arranged at a seabed (1) surrounded by a body of water (3), the subsea system (10) comprises:- a subsea control module (100’;100”) according to any one of claims 18-19;- a Xmas tree (11);- a connection port (13 13 ”);- a fluid conduit (12’; 12”) in fluid communication with the connection port (13’;13”).

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