Subsea High Bandwidth Data Transfer Using Fiber Optic Technologies

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1 Subsea High Bandwidth Data Transfer Using Fiber Optic Technologies Richard T. Jones Research and Development, Fiber Optics Teledyne ODI / Teledyne Oil & Gas Daytona Beach, USA [email protected] Jeremy Lucas Reliability Department Teledyne ODI / Teledyne Oil & Gas Daytona Beach, USA [email protected] Abstract High bandwidth data transfer is critical in applications where large quantities of information are being transmitted. This is of particular interest to the Ocean Science Community, which relies on collecting data from sensors on the ocean floor. Multiple approaches for data transfer are illustrated, and the strengths and weaknesses of each are highlighted in this paper Fiber Optic technology has been widely adopted in subsea communications due to the inherent reliability and the passive nature of fiber optics. A brief history of subsea fiber optic interconnects is developed, with an accent on projects in the Oceanographic arena. An overview of the reliability of fiber optic wet-mate connectors in subsea is reported, augmented with an emphasis on case histories for subsea fields in Oil & Gas markets where the largest quantities of fiber optic connectors have been deployed. Advancements for subsea connectivity are discussed, specifically related to a novel approach utilizing existing technology. This approach utilizes standard electrical wet-mate connectors on either end. Marinized media converters are contained within the back shells of each electrical connector which convert the Ethernet signal from electrical to optical. The optical signal can then be transmitted over distances far exceeding standard subsea electrical Ethernet capabilities. In this way, optical Ethernet performance can be achieved with standard electrical Ethernet hardware interfaces extending the step out distance from 100 m (limit of standard electrical Ethernet subsea jumpers) to up to 10 km. use. However, the maximum data transfer rates achievable are insufficient for technologies that demand data transfer rates in excess of 20 kb/sec. Electrical DSL offers higher bandwidth than modem technology at reasonably long distances, but the available bandwidth decreases as a function of length and still does not provide enough bandwidth for many data rich technologies ( kb/sec, up to 15 km). Electrical Ethernet has proven to be reliable and high bandwidth, but is limited to short step out distances (< 100 meters). Electrical Ethernet is extensively used for short distance subsea communications in the Oil & Gas market. In cases where step out distances are too long or bandwidth requirements are too great, optical Ethernet is utilized. Optical Ethernet is reliable with high bandwidth and is not limited to short lengths, but comes with higher cost of implementation. This cost is not limited to the optical wet-mate connectors, but also includes the optical infrastructure required in the electronics module to which the optical connectors are mated. A graphical representation of these data transfer paradigms is shown in Fig. 1. Keywords data transfer; bandwidth; fiber optics; wet-mate; connector; Ethernet I. HIGH BANDWIDTH DATA TRANSFER As the sensors used in the subsea environment increase in number and capability, the amount of data transmitted by these sensors continues to increase. This data must be collected and transmitted back topside where it can be reduced and utilized. Some of the approaches to provide data transfer bandwidth explored in this paper include electrical modems, electrical DSL, electrical Ethernet and optical Ethernet. Figure 1. Data Transfer Paradigms for subsea bandwidth In Fig. 1, the red arrows denote that the technology can expand in the directions shown. Conventional electrical modems can transmit data over long distances. This technology is by far the most mature for subsea

2 TABLE I. Oil and Gas Marlin MA-D6 Canyon Express Nakika Thunder Horse Greater Alwyn Ormen Lange BP GOM Fiber NOTABLE PROJECTS USING WET-MATE FIBER OPTIC CONNECTORS II. SUBSEA FIBER OPTIC CONNECTOR RELIABILITY Due to the increasing number of subsea oil & gas wells, the majority of subsea fiber optic wet-mate connectors have been deployed on Oil & Gas projects. These projects represent approximately 68% of the fiber optic connectors deployed in the world today. Oceanographic projects represent approximately 15% of global wet-mate fiber optic connector deployments. A table of some of the notable projects where fiber optic connectors have been deployed for both the Oil & Gas and Oceanographic markets is shown above in Table 1. The use of subsea fiber optic connectors has increased dramatically over the last several years. Despite the growing popularity of these connectors, many concerns remain in both the Oceanographic and Oil & Gas industries about the reliability of these connectors. Concerns about the reliability of fiber optic connectors stem from a number of factors. A very small number of highly publicized hybrid (combined fiber and electrical) connector failures in the Oil & Gas industry have led some companies to design these out of their systems for fear of similar issues. However, when compared to other subsea components, fiber optic connectors are found to have excellent reliability. The Offshore Reliability Data (OREDA) handbook gives reliability data collected by multiple Oil & Gas companies about many components which are used subsea. Although a category is included for fiber optic couplers, no failures have been reported to this database. However, manufacturer records more accurately track the number of failures that have occurred on these units, and include other subsea industriess outside of Oil & Gas. Data analysis has been performed on one company s fiber optic connectors to match the calculations used in the OREDA handbook. The results from this analysis, along with the results from the OREDA handbook for various other categories of subsea equipment are shown in Table 2. TABLE II. Component Wet-Mate Fiber Optic Connectors Temperature Sensor Control System Pressure Sensor Control System Power Supply Unit Control Systems Subsea Electronic Module Control Systems Hydraulic Coupling Control Systems Solenoid Control Valve Control Systems Oceanographic Donet Neptune Canada Antares Nemo OceaNet OCB TWERC Macho Venus OREDA FAILURE RATES Failure Rate (per 10 6 hours) A further concern about subsea fiber optics is that the validity of metrics, especially ones that report good reliability, is often questioned. There are two main reasons for this. First, due to the perception of poor reliability of subsea fiber optic equipment, it is difficult for many people to accept the improvements in reliability that have occurred over the past couple of decades. Second, many people question the methods used to capture and calculate the reliability of subsea equipment, which presents a large challenge. When a piece of subsea equipment fails after deployment, it is often not brought up for repair, with operators instead, choosing to employ backup systems. This presents a problem to companies attempting to calculate reliability based on field returns, which would give the most accurate information about field reliability. To overcome these problems, a systematic approach has been set up to ensure the capturing and validation of accurate information regarding field failures. This approach can be represented as an iceberg, as shown in Fig. 2. Figure 2. Reliability Iceberg

3 The tip of the reliability iceberg, which is most visible to customers and end users, is the published reliability metrics. Because these metrics are what is most visible, it is sometimes hard for customers and end users to see the rest of the structure to the system, in the same manner that it is hard to see the structure that supports the tip of the iceberg. However, when taking a deeper look, it is apparent that there are a number of levels below these metrics. The metrics are directly supported by field data, which is captured for all units that are returned. Nearly all failures that are identified pre-deployment during testing or integration are collected as field data due to customer returns. Many of the failures that occur subsea after deployment are also captured, as a large number of these failed units are sent back. However, the return of units that failed subsea may occur only after a long delay, and when a more critical failure forces the end user to bring up the entire system, and connector repairs are feasible. In order to both improve the accuracy of the number of recorded failures and the speed at which they are recorded, a Field Failure Report system was created to supplement the standard returns system. It was discovered that many of the units that have failed subsea and have not been returned, were being reported to the manufacturer, though usually not through a formal process. This would usually take the form of an or phone call to an engineer to discuss the issue. Formalizing this process has been accomplished by requiring engineers who have contact with customers to report all failures that are not being returned to the manufacturer on a Field Failure Report form. This form requires an investigation into the issue by the engineer, which includes collection and review of all data that is available from the customer and a review of previous field failures to look for trends in the failure history. The Field Failure Report can subsequently be replaced by a more thorough investigation if and when the unit is eventually returned to the manufacturer. The collection of field data is therefore supported by a well-defined process. This process aims to capture all of the field data in a well defined manner, with failures classified by product line, cause of failure, failure mode, and other important aspects. This classification system was modeled after ISO 14224, which defines the standard practices for collection and exchange of reliability data for subsea equipment. This standard, which is itself based on lessons learned from OREDA, defines a number of steps that must be taken to ensure accurate and useful data collection. Data categories, format of the data, boundary diagrams to separate equipment into various product lines, and database structure are all addressed in this standard. However, even while using this standard, it is possible to miss important failure data due to customers and end users not reporting failures. To ensure that all failures have been reported, validation with customer data is performed. Through regular meetings with top Oil & Gas customers and hosting conferences with Oceanographic customers, data exchange is made possible. By comparing the failure database of the manufacturer to the failure database of each customer, any differences can be addressed and corrected. Through this process, virtually all remaining failures are captured, ensuring that the data, and therefore the metrics are accurate. The failure rate that was reported in Table 2 is for operational reliability assuming perfect use of wet-mate fiber optic connectors. This takes into account only the failures that have occurred due to either design or manufacturing issues, and not issues that have occurred due to use of the connectors beyond their design limitations. However, the majority of issues that have occurred subsea have not been due to design or manufacturing issues, but due to the challenges of ROV operations. When taking into account the typical use of wetmate fiber optic connectors, the failure rate, as calculated by OREDA calculations, is found to be 0.28 failures per 106 hours. Due to this discrepancy and in consideration of the ROV deployment challenges, methods of improving the operational reliability of the connectors were examined. Through discussions with customers about how to improve the usability of these connectors, two areas of potential improvement in ROV operation were found. First, it was discovered that mating the connectors within the correct angle limitations of 5 degrees can be difficult for many ROV operators. For this reason, a new Gross Alignment Funnel (GAF) was created. This improved the angle of acceptance from 5 degrees to 30 degrees, and prevented the connectors from engaging until proper alignment was achieved. This prevents failures due to mechanical damage of the connector shells. Fig. 3 shows this mating improvement. Figure 3. Connector mating with and without Gross Alignment Funnel (GAF) It was also found that it was difficult to determine whether or not the connectors were fully mated. For this, a new Enhanced Latch Indicator (ELI) was designed that allows the operator to verify through the means of highly visible indicators located near the handle that the connectors are fully latched together. Both of these improvements have allowed

4 end users to greatly improve the operational rreliability of wetmate fiber optic connectors while increasing R ROV operational efficiencies and reducing total deployment ccosts at the same time. Fig. 4 demonstrates this improvement. This technology could be especially useful to the d to set up sea floor Oceanographic community. It is desirable experiments reasonably far away from the node as to not disturb or influence the sea life that, in some cases, is being studied. The Extended Ethernet Fllying Lead can provide this long step out. ystem, the conversion from In an optical communications sy electrical to optical Ethernet occurrs inside of the electronics module to which the optical connecttor is mated. With this new approach, the flying lead becomees a line replaceable unit (LRU) in the event that a media con nverter fails. In the event of a failure, this LRU is more easily retrieved r at lower cost than the electronic module. Fig. 6 illustraates this approach. Figure 4. Latch indication with standard indicattors (left) and Enhanced Latch Indicators (right) III. EXTENDED ETHERNETT In section I of this document, different subbsea data transfer paradigms were discussed. Referring back to Figure 1, today s subsea high bandwidth data transfer needs cann often be met by utilizing conventional electrical Ethernet, but tthat technology is limited by physics to a length of about 1000 meters between Network Interface Cards (NIC). An advanccement in subsea connectivity is now discussed, specifically reelated to a novel approach utilizing existing technology. This approach utilizes standard electrical wet-mate connectors on either end. Marinized media converters are contained within the back shells of each electrical connector which connvert the Ethernet signal from electrical to optical. The optical ssignal can then be transmitted over distances far exceeding standard subsea electrical Ethernet capabilities. In this way, optical Ethernet performance can be achieved with standard electrical Ethernet m 100 m to up to hardware extending the step out distance from 10 km. Figure 5 shows the Extended Ethernnet Flying Lead (E2FL). Figure 5. Extended Ethernet Flying Leead Figure 6. Approach for creating a line reeplaceable unit (LRU) with the Extended Ethernet Flying Lead(E2FL). For further reliability considerationss, two redundant converters can be used at each end of the fly ying lead. High reliability, aerospace qualified converters should s be used in these assemblies. Due to the already complex nature of subsea control and/or networking modulles, the placement of the media converters outside of theese modules as an LRU provides an opportunity to maximizze reliability by minimizing the number of failures in time (FIT) for the more complex assembly.

5 IV. SUMMARY Modern and emerging sensors and systems now demand greater data transmission capability in networking options. This trend will continue to grow as sensors and systems develop further. Subsea networks will in turn require modular connectivity using interconnect systems capable of enabling this high bandwidth availability. Just as sensors have become more reliable over time, interconnect systems have also evolved. The need for enhanced reliability and the ability to collect complete data and confidently measure reliability is ever increasing. Historical perceptions of reliability gray areas based on inconsistent or variable interpretation of the accuracy and availability of reliability data need to be refreshed. This can be accomplished by studying the advances in scientific methods and standards, that have been developed in demanding industries such as Oil & Gas Exploration, Oil & Gas Production, and Aerospace. These processes and methods and the resulting data reporting and measurement are the responsibility of all of the stakeholders and will require consistent participation in order to continually improve. The processes available today are significantly more valuable than those available several years ago. The improvements and the value of the reliability programs will continue to increase. Finally, consideration for high data transfer rates can be given through a variety of existing and emerging solutions, many of which will offer novel approaches using modifications to existing interconnect solutions. In order to be effective solutions, they must be highly reliable, reduce development investment costs and lower the total cost of associated risk. These solutions all support collecting increasingly more complex and better data in Ocean Observing and Monitoring Systems.