Connection assembly, sensor assembly and subsea cable harness Field of the invention

The invention relates to a connection assembly, sensor assembly and subsea cable harness for subsea use. Background

Subsea pressure and temperature sensors are known and are for example used to measure pressure or temperature at different locations on a subsea hydrocarbon production or processing facility, for example on a subsea Christmas tree or in a subsea flow line.

Conventional systems employ for example a single pressure sensor to which a single cable is connected. The cable pro- vides data communication and power to the sensor. The sensor can for example be connected to a subsea control module.

For reasons of achieving a safe and secure operation, two such pressure sensors can be provided to achieve redundancy. The problem with such configurations is that they require a significant amount of space since each pressure sensor needs to be mounted on a different position on the flow line or on the Christmas tree. Further, such configurations are costly. Summary

Accordingly, there is a need for improving measurements in a subsea application. This need is met by the features of the independent claims. Embodiments of the invention are described in the dependent claims . According to an embodiment, a connection assembly for connecting at least two subsea cables, in particular oil-filled hoses, to a dual output subsea sensor is provided. The connection assembly comprises:

- an adapter piece configured to be mounted to a rear part of the subsea sensor,

a sensor port in the adapter piece through which at least a first sensor connection and a second sensor connection are led to the dual output subsea sensor,

- a first port for providing a connection to a first subsea cable of the subsea cables,

a second port for providing a connection to a second subsea cable of the subsea cables,

a first penetrator arranged in the first port, wherein the first penetrator provides a liquid tight seal between an interior space of the adapter piece and a duct connected to the first port, and wherein the first penetrator leads the first sensor connection through the first port, and

- a second penetrator arranged in the second port, wherein the second penetrator provides a liquid tight seal between the interior space of the adapter piece and a duct connected to the second port, and wherein the second penetrator leads the second sensor connection through the second port.

The sealing provided by the first penetrator and by the second penetrator is such that there is no fluid communication between the duct connected to the first port and the duct connected to the second port through the adapter piece.

Such configuration requires only relatively little space since it becomes possible to employ a dual output subsea sensor and to connect two subsea cables to such sensor. In particular, oil-filled hoses can be used in such configuration, which has the advantage that the assembly can be installed at large water depths, for example in excess of 1,000 m. Since two separate penetrators are provided for the first and second ports towards which the subsea cables are connected, an oil volume in the first subsea cable can be kept isolated from an oil volume of the second subsea cable. Accordingly, when one subsea cable is damaged so that water leaks into the subsea cable, the other subsea cable remains unaffected and operation of the subsea sensor can continue.

According to an embodiment, the first penetrator and/or the second penetrator comprise a penetrator body made of metal. The metal penetrator body may resist a large pressure differ- ence between for example a pressure in the duct connected to the first port or second port and the interior of the adapter piece .

For example, the adapter piece may be configured to maintain a predefined interior pressure below 5 bar, preferably below 1.5 bar when deployed in a subsea environment. However, in subsea environment the pressure in the duct connected to the first port or second port may be some hundred bar, for example 300 bar in a depth of 3000 m.

According to another embodiment, the first penetrator is sealed in the first port by a weld. Additionally or as an alternative, the second penetrator is sealed in the second port by a weld. By welding the first penetrator and/or second pen- etrator to the corresponding first port and second port, respectively, a reliable sealing between the penetrators and the ports may be achieved which may resist the above- described high pressure difference between a pressure in the duct connected to the first port or second port and the inte- rior of the adapter piece.

In particular, the first and second penetrators may each comprise a corresponding penetrator body having one or more through-holes for leading the first sensor connection and the second sensor connection through the first penetrator and the second penetrator, respectively. The one or more through- holes may be filled with a glass material and may thus provide a glass-to-metal seal sealing the sensor connections within the through-holes of the penetrators . The glass-to- metal seal provides a high resistance against the pressure difference between the pressure in the interior space of the adapter piece and the pressure in the duct connected to the first and second ports. Furthermore, the glass-to-metal seal electrically isolates the sensor connections from the metal penetrator body.

According to another embodiment, the first port and/or the second port provides a mechanical interface for the connection of a subsea cable, for example an oil-filled hose, in particular for the connection of an MKII fitting of an oil- filled hose. By providing a mechanical interface for the connection of an oil-filled hose, in particular a mechanical in- terface for the connection of the well-known MKII fitting, the connection assembly may be easily integrated into existing and new subsea constructions.

Furthermore, the connection assembly may comprise a first connection adapter mounted to the first port or mounted to the adapter piece and providing the first port. For example, the first connection adapter may provide a receptacle for receiving a connector provided at the duct to be coupled to the first port. In other words, the connection adapter may pro- vide a mechanical interface for connecting a duct provided with a specific connector, for example an MKII fitting of an oil-filled hose. Other kinds of the first connection adapter may provide a mechanical interface for connecting to other connector types or for directly connecting to a subsea cable. This enables a support of a large variety of connection schemes. Likewise, the connection assembly may comprise a second connection adapter mounted to the second port or mounted to the adapter piece and providing the second port . The first and/or second connection adapter may be sealed to the respective port by means of at least two 0-ring seals. This may enable a reliable sealing between the first and/or second connection adapter and the respective first or second port .

The first and/or second connection adapter may be filled with dielectric liquid, in particular an oil. The first and/or second connection adapter may be filled with the same dielectric liquid as the duct connected to the corresponding first and second connection adapter, and a fluid connection between the dielectric liquid in the duct and the dielectric liquid in the corresponding first and second connection adapter may be provided. However, the first and second penetrators provide a separation between the interior space of the adapter piece and the dielectric liquid filling the duct and the corresponding first and second connection adapter.

According to another embodiment, the sensor port comprises a mechanical interface for mounting the adapter piece to a mounting flange or sensor housing of the subsea sensor. For example, the subsea sensor is mounted to the mounting flange and the adapter piece is welded to the mounting flange. Thus, a fluid tight and pressure resistive connection between the mounting flange and the adapter piece may be provided.

According to another embodiment, the connection assembly com- prises a mounting flange for mounting the subsea sensor. An interior space of the mounting flange, in which the subsea sensor is disposed, and an interior space of the adapter piece are in fluid communication. The interior space of the mounting flange and the interior space of the adapter piece may be filled with gas, for example dried nitrogen gas.

In particular, the adapter piece may be configured to maintain a predefined interior pressure, for example a pressure below 5 bar, preferably below 1.5 bar when being deployed in a subsea environment. This enables an operation of electrical and electronic components which are not designed for an operation under subsea high pressure conditions of for example a few hundred bar . According to another embodiment, the adapter piece is extending along an axial direction and the sensor port is provided on an end face of the adapter piece. The end face is perpen- dicular to the axial direction. The first and second ports are provided on the lateral surface of the adapter piece. The lateral surface is substantially parallel to the axial direction. Thus, a plurality of ports may be arranged at the adapter piece. For example, the first port and the second port may be provided on substantially opposite lateral surfaces of the adapter piece. Additionally or as an alternative, the ports may be arranged in a row along the lateral surface of the adapter piece in the axial direction. According to an embodiment, the first sensor connection and/or the second sensor connection comprises at least two electrical conductors for data transmission and preferably furthermore two electrical conductors for power transmission. Thus, a redundant data transmission and a redundant power transmission can be provided.

According to another embodiment, a sensor assembly is provided. The sensor assembly comprises the dual output subsea sensor and a connection assembly as described above. The connec- tion assembly is mounted to the subsea sensor. For example, the subsea sensor is mounted at the sensor port of the connection assembly.

According to an embodiment, the dual output subsea sensor comprises at least two pressure sensing elements and/or at least two temperature sensing elements. The output of the respective sensitive elements is communicated on the first and second sensor connections. By providing at least two pressure sensing elements and two the temperature sensing elements, a completely independent and redundant pressure and temperature measurement and determination via two connected subsea cables is enabled. According to another embodiment, a subsea cable harness is provided. The subsea cable harness comprises a first subsea cable including electrical conductors for providing a first sensor connection, a second subsea cable including electrical conductors for providing a second sensor connection, and a connection assembly as described above. The first subsea cable is connected, directly or indirectly, to the first port of the connection assembly, and the second cable is connected, directly or indirectly, to the second port of the connec- tion assembly. The first penetrator leads electrical conductors of the first sensor connection through the first port into an interior space of the adapter piece. The second penetrator leads electrical conductors of the second sensor connection through the second port into an interior space of the adapter piece. An indirect connection between the first subsea cable or second subsea cable and the first port or second port, respectively, may be provided by the above described mechanical interface and/or the first and second connection adapters, respectively. Additionally, a fitting, for example an MKII fitting, may be provided for indirectly connecting the first and/or second subsea cable to the corresponding port .

The first subsea cable and/or the second subsea cable may comprise a corresponding oil-filled hose. Furthermore, the subsea cable harness may comprise the sensor assembly described above.

Thus, similar advantages as described above in connection with the connection assembly are achieved by the sensor assembly and the subsea cable harness.

Although specific features are described in the above summary and the following detailed description in connection with specific embodiments, it is to be understood that the features of the different embodiments of the invention can be combined with each other unless noted to the contrary. Brief description of the drawings

Figure 1 shows a sectional side view of a sensor assembly, a connection assembly and a subsea cable harness according to an embodiment of the invention.

Figure 2 shows a front view of a connection assembly and a sensor assembly according to an embodiment. Figure 3 shows a perspective view of the connection assembly and the sensor assembly of Figure 2.

Figure 4 shows a sectional view along the line A-A of the connection assembly and the sensor assembly of Figure 2.

Figure 5 shows a front view of a penetrator that can be used in embodiments of the invention.

Detailed description

In the following, exemplary embodiments of the invention will be described in more detail. It is to be understood that the features of the various exemplary embodiments described herein may be combined with each other unless specifically noted otherwise. Same reference signs in the various drawings refer to similar or identical components.

Figure 1 shows a subsea cable harness 300 comprising a sensor assembly 200 connected to a first subsea cable 301 and a se- cond subsea cable 302. The sensor assembly 200 comprises a subsea sensor 220 and a connection assembly 100. The subsea sensor 220 is mounted to a mounting flange 210 of the connection assembly 100. The connection assembly 100 includes an adapter piece 110 that has a first port 111, a second port 112 and a sensor port 115. The adapter piece 110 is mounted to a rear part of the subsea sensor 220. For example, as shown in Figure 1, the adapter piece 100 is mounted to the rear part of the subsea sensor 220 via the mounting flange 210. The mounting flange 210 may be coupled to a subsea flow line or subsea Christmas tree in which a pressure and temperature of a fluid therein is to be detected and monitored.

In the first port 111, a first penetrator 121 is provided and sealed. In the second port 112, a second penetrator 122 is provided and sealed.

The bodies of penetrators 121, 122 are made of a metal. Sealing between the penetrators 121, 122 and the adapter piece 110 may be done by means of a weld 161 and 162, respectively. The adapter piece 110 is made of metal, in particular stain- less steel.

The first subsea cable 301 in form of an oil-filled hose is connected to the first port 111. It is to be noted that this connection can also be an indirect connection via a connec- tion adapter 141 as shown in Figure 4. The second subsea cable 302 in form of an oil-filled hose is connected to the second port 112. It is to be noted that this connection can also be an indirect connection via a connection adapter 142 as shown in Figure 4.

The connection assembly 100 may, for example, comprise two such connection adapters 141, 142 that are mounted to the first and second ports, respectively, for providing a mechanical interface for mounting the respective subsea cable. In other configurations, such connection adapters 141, 142 may provide the first and/or second ports 111, 112, and the first and/or second penetrators 121, 122 may be provided in such connection adapters. An oil-filled hose has a flexible outer jacket that is filled with oil and in which respective lines are disposed, such as power lines and/or data lines. Due to the flexibility and the oil filling, the internal pressure in such hose is balanced to the outside water pressure while the liquid filling prevents a collapsing of the hose.

By means of the first and second penetrators 121, 122, it is ensured that the oil volumes of the two oil-filled hoses 301, 302 are kept separate and are kept separate from the interior space 105 of the adapter piece 110. Accordingly, if one hose leaks, the other hose and the interior space 105 of the adapter piece 110 are not affected.

The subsea sensor 220 is a dual output subsea sensor that gives out at least two measurements taken by two sensor elements. The sensor 220 may comprise two pressure sensor elements for two independent pressure measurements. The sensor 220 may comprise two temperature sensor elements for two independent temperature measurements. Preferably, it comprises both, two pressure sensor elements and two temperature sensor elements . Processed or raw sensor readings are given out on the first sensor connection 131 for a first pressure sensor element and a first temperature sensor element, and on the second sensor connection 132 for a second pressure sensor element and a second temperature sensor element of subsea sensor 220. In oth- er words, information concerning pressure and temperature detected at the sensor elements are output separately via corresponding sensor connections. For example, information concerning the pressure and temperature detected at the first pressure and temperature sensing elements may be output via the first sensor connection 131, and information concerning the pressure and temperature detected at the second pressure and temperature sensing elements may be output via the second sensor connection 132. The first and second penetrators 121, 122 lead the first and second sensor connections 131, 132 from an interior space 105 of the adapter piece 110 into a duct that is in fluid communication with the interior of the respective oil-filled hose. The duct can be provided by the respective port, the above mentioned connection adapter 141, 142 or the oil filled hose 301, 302 - the duct is essentially a volume on the other side of the respective penetrator 121, 122 into which the respec- tive sensor connection 131, 132 is led by the respective penetrator 121, 122.

Preferably, the first and second sensor connections 131, 132 each comprise two electrical data lines and two power lines for supplying electrical power to the respective sensor element (s) . Each sensor connection 131, 132 may comprise for example one or more electrical wires.

In the example of Figure 1, the adapter piece 110 is mounted to the mounting flange 210. The mounting flange 210 is mounted to the equipment at which the sensor reading is to be taken, for example a flow line in Figure 1. The mounting flange 210 can form a part of the connection assembly 100. In the example of Figure 1, the adapter piece 110 is mounted to the mounting flange 210 by means of a weld 165. As can be seen, a volume 221 at the rear side of the sensor 220 within the mounting flange 210 is in flow communication with the interior space 105 inside the adapter piece 110. Accordingly, medium can flow between the volumes 221, 105. Preferably, these volumes 221, 105 are filled with a gas, such as dried nitrogen .

The connection assembly 100 may be adapted to maintain a pre- defined pressure inside the volumes 221, 105 when installed subsea, for example a close to atmospheric pressure, e.g. a pressure below 5 bar or below 1.5 bar.

For example, (not shown) electrical or electronical compo- nents for processing sensor data may be provided within the volumes 221, 105. Due to the predefined pressure, which may be much lower than ambient pressure in subsea conditions, the electrical or electronical components may be designed for these lower pressures and need not to be pressure resistant to high pressures in subsea environments.

For example, in volume 221 electronic cards for transmitting and/or processing sensor readings may be disposed, or they may be disposed in a rear part of sensor 220.

Figure 2 shows a front view of the sensor assembly 200 including the connection assembly 100 according to a further embodiment. Accordingly, the above explanations also apply to the embodiment of Figure 2. In Figure 2, the subsea cables 301, 302 in the form of oil-filled hoses are mounted to the first and second ports 111, 112 (see also Figure 4) by means of the connection adapters 141, 142. In the example of Figure 2, the adapter piece 110 is extending along an axial direction perpendicular to the drawing plane of Figure 2. The sensor port 115 is provided at an end face of the adapter piece 110 that is perpendicular to the axial direction, i.e. in the drawing plane of Figure 2. The first and second ports are provided on a lateral surface of the adapter piece 110. The lateral surface is substantially parallel to the axial direction. The first port and the second port are provided on substantially opposite lateral surfaces of the adapter piece 110. For connecting the subsea cables 301 and 302, at each port a corresponding connection adapter 141 and 142 is provided. Connection adapter 141 may be sealed to its corresponding port by means of at least two 0-ring seals. Likewise, connection adapter 142 may be sealed to its corresponding port by means of at least two 0-ring seals.

The connection adapters 141 and 142 provide a receptacle for receiving a fitting at the end of the corresponding subsea cable 301, 302. For example, a receptacle for receiving an MKII fitting may be provided at each of the connection adapt- ers 141, 142. Corresponding MKII fittings may be provided at the end of each of the subsea cables 301, 302. Figure 3 shows a perspective view of the sensor assembly 200 including the connection assembly 100 of Figure 2, and these can form part of embodiments of the subsea cable harness 300. Figure 4 shows a sectional view of the sensor assembly 200 of Figure 2 taken along the line A-A. The sensor assembly 200 comprises the subsea sensor 220 and the connection assembly 100. The subsea sensor 220 is mounted at the mounting flange 210 of the connection assembly 100. The mounting flange 210 is coupled by a weld 165 to the adapter piece 110. The adapter piece 110 provides two ports, the first port 111 and the second port 112. In the first port 111 a first penetrator 121 is arranged. The first penetrator 121 is made of metal and sealed in the first port 111 by a weld 161. In the second port 112 a second penetrator 122 is arranged. The second penetrator 122 is made of metal and sealed in the second port 112 by a weld 162. Thus, an interior space within the adapter piece 110 extending from the first and second penetrators

121, 122 to the subsea sensor 220 is completely isolated from an exterior and may be filled with gas, for example dried nitrogen 170.

Connection adapters 141, 142 are provided in the ports 121,

122, respectively. Ducts 145, 146 are provided by the connec- tion adapters 141, 142 and may extend into the oil-filled hoses 301 and 302, which are not shown in Figure 4. When connected to the oil-filled hoses 301, 302, the ducts 145, 146 may also be filled with liquid or oil. The liquid- filled interior space of the connection adapters 141, 142, which pro- vide the ducts 145, 146, is visible in Figure 4.

The connection adapters 141, 142 may provide receptacles for receiving fittings, for example MKII fittings. The connection adapters 141, 142 may be sealed to the respective port 111, 112 by means of two 0-ring seals 171, 172.

Figure 5 shows a front view of the first or second penetrator 121, 122, which may be configured similarly, with exemplary through-connections. The penetrator 121, 122 comprises a penetrator body having one or more through-holes for leading connections through the penetrator. The penetrator body is made of metal .

In the example shown in Figure 5 the penetrator body has four through-holes for leading connections 1 to 4 through the penetrator. Connections 1 and 2 provide electrical power as part of the first or second sensor connection 131, 132, and con- nections 3 and 4 provide data communication as part of the first or second sensor connection 131, 132. Data communication may for example occur by means of a differential serial bus, such as CAN (controller area network) . Each through-hole may be filled with a glass material and may thus be sealed by a glass-to-metal seal. In detail, a connection 1-4 extending through the through-hole is completely and continuously surrounded by the glass material. The glass material is also continuously in contact with an inner wall of the through- hole .

The glass-to-metal sealing of the connections in the through- holes 1-4 of the penetrator body provides a reliable sealing at high pressure differences. Further, the metal penetrator body may be welded to the corresponding port thus providing a reliable sealing even at high pressure differences which may exist between the oil-filled duct 145, 146 and the interior space 105 of the adapter piece 110.