By Zhong, Qian
Development of OADM Trunk-and-Branch Suite of Undersea Hardware Leads Communication Systems into the Future Although undersea telecommunications is a mature industry that routinely installs and maintains transoceanic fiber optic cables capable of providing reliable performance for more than a quarter of a century, the demand for offshore technology continues to grow.
Oil and gas companies are looking to deploy larger, more dependable subsea systems that are cost effective and will provide them with increased Internet speed and more bandwidth to support applications such as voice over Internet protocol. Furthermore, oil platforms and wells are in need of more reliable communications systems in order to avoid profit losses caused by slowdowns in production. Increased security in communications is an additional incentive.
Optical add/drop multiplexing (OADM) continues to evolve in response to the demand for more advanced offshore technology that will meet the requirements for reliable connections between onshore and offshore platforms. By using the available bandwidth to distribute small units of capacity to a large number of offshore platforms, an OADM system allows a chain of oil rigs to be connected to a single undersea fiber optic network. OADM provides each platform with a dedicated channel and bandwidth, therefore ensuring that signals will continue to flow if ever another rig’s connection is interrupted. This type of system is referred to as a trunk-and- branch system. While the trunk is the portion that connects the two ends of the system, the branches connect the oil platforms to the trunk.
OADM Interconnect Devices
In order to accommodate oil and gas companies who are increasingly moving their platforms farther away from shore, telecommunications providers like Tyco Telecommunications have developed a trunk-and-branch suite of undersea hardware to provide real-time communication to and between offshore oil and gas platforms. The hardware, which functions to connect branches to the main cable trunk of an OADM system, includes a dynamic riser cable (DRC), rig termination and interconnecting joint working together as a unit; a fiber distribution canister (FDC); and a branching optical amplification unit
The DRC is a high-strength, torquebalanced cable that is specifically designed to withstand the dynamic environment surrounding a deepwater oil platform. The top end of the DRC is joined to the platform by a rig termination device. At the other end, the DRC is secured to the ocean floor by wearprotected anchors. The interconnecting joint then joins the DRC to the rest of the network cable.
The FDC serves as an outlet to connect certain fibers from the platform to the network, while other fibers are terminated locally for later plug-in accessibility. The FDC can support up to four wetmate connectors, which allow new fibers to be connected after the system is installed without having to cut into the cable. Remotely operated vehicles can quickly install the additional wetmate connectors as they are needed.
Last, the branching unit (BU), which is an optical amplification unit (repeater), serves to connect each of the platforms in the system to the network cable; simply, it connects the branches to the trunk. If a system repair is ever needed, the BU also provides the ability to isolate each of the branches. The OADM power-switched branching unit (OADM-PSBU) can support optical and controllable electrical connections between three cables that terminate at the unit, in addition to a local sea ground, which is built into the unit. Furthermore, the OADM-PSBU provides for direct routing of optical signals between two fibers and shared optical routing needed for optical add/drop features.
To provide maximum protection and reliability, the OADM-PSBU is enclosed in a cylindrical container made of a beryllium-copper alloy. The design not only guards the optical and electrical elements of the BU from the volatile ocean environment, it also provides a high-strength connection among the three cable terminations and voltage isolation between sea ground and system potential.
Advantages of OADM
“There are three key technological advantages of the use of undersea fiber optic telecommunication devices and/or systems in the oil and gas industry. First, these systems use commercially available submarine telecommunications products that have established track records, can be readily modified to suit specific offshore applications and are highly reliable. Often such products have a design life of more than 25 years and performance availability in excess of 99.99 percent. second, the devices and systems optimize the technology choices between repeaterless transmission for close platforms or amplified transmission for distant platforms. Finally, the devices exploit miniaturization, with compact terminals and low power requirements, making them well suited for the extreme space limitations on oil platforms.
Application of Technology
For offshore systems in which interconnect communication is desired, OADM-BUs are used to connect a series of platforms to a trunk cable that connects two end-cable stations. Communication can be established between different platforms as well as between a platform and a cable station. The advantages for this connectivity topology are flexibility, meaning more platforms can be added if designed appropriately, and independence, meaning one platform does not have to be dependent on another to ensure communication, a feature that is extremely important in the event of a natural disaster.
Once the submerged plant, which includes the cable, BUs and underwater interconnect devices, is in place, connectivity to the platform is then established via a riser cable and specific terminal gears. The result is the easy establishment of either a traditional or an Internet protocol-based network.
BP (London, England) has deployed such technology in a system that initially connects each of two shore stations with a series of seven platforms. Traffic is carried on one fiber pair (FP), with connectivity between each shore station and each of the seven platforms. A total design capacity of 640 Gigabits per second per FP is provided, and each platform is equipped with routers providing Gigabit Ethernet interfaces for communication needs.
The system is designed with flexibility to accommodate future expansion to 32 platforms per FP, with a total of two FPs, supporting individual FP ownership of transmission.
The same technology platform is being considered for other oil and gas applications in a variety of locations, including the Caribbean Sea, Africa and Southeast Asia, where oil and gas exploration activities are abundant.
Using existing undersea telecommunication fiber optics technology and products, offshore oil and gas platforms can enjoy reliable, secure, cost-effective and expandable communication connectivity.
Specifically, Tyco Telecommunications’ trunk-and-branch suite of interconnect devices, which includes the DRC, FDC and OADM-PSBU, is a significant development in providing offshore platforms with the most reliable real-time communications.
It is envisioned that this platform of versatile, reliable and cost-effective communications systems can be easily adapted to accommodate the growing needs of the industry, as well as serve as the bridge for introducing new technologies where the transport media evolve in the form of both capacity and structure.
A typical con figuration of a suite of technological components (or an undersea communication system connecting to oil and gas platforms.
(Above) A trunk and branch platform/cable station configuration.
(Right) Wavelength distribution in a hypothetical trunk-and- branch platform connectivity configuration.
(Bottom) The OADM-PSBU serves to connect each of the oil platforms in a system to the main network cable, otherwise known as the trunk.
“Tyco Telecommunications’ trunk-and-branch suite of interconnect devices is a significant development in providing offshore platforms with the most reliable real-time communications.”
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By Dr. Qian Zhong
Director of System Engineering
Morristown, New Jersey
Dr. Qian Zhong is director of system engineering at Tyco Telecommunications. He started his career at AT&T Bell Laboratories in the optical fiber research department and then joined the undersea systems unit, which became Tyco Telecommunications. Before becoming director of system engineering, Zhong headed the advanced technology research and cable development organizairons.
Copyright Compass Publications, Inc. May 2008
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