August 2023
Special focus: Offshore operations

Simplifying testing on subsea umbilical installation campaigns

An automated cable monitoring system for testing subsea electrical assets is an efficient tool used in fault-finding and construction campaigns. It is fast and relatively simple to deploy, compared to downlines or platform-led testing. The technology delivers accurate data on the health of subsea assets.
Cynthia Pikaar / C-Kore Systems

C-Kore Systems is simplifying testing processes for operators and installation contractors during umbilical deployment. The company’s patented subsea testing tools help operators reduce their carbon footprint on subsea operations. By shortening the time required for testing, providing high quality data, and reducing the offshore personnel count, operators can perform subsea testing operations faster reducing NPT and operational costs, Fig. 1. 

Fig. 1. Subsea umbilical being installed with C-Kore units.

Fabrication and installation challenges. Umbilicals are the arteries in any subsea production system. Without operational umbilicals, fluids, power and communications can’t flow to the subsea control modules, and production from the wells is disrupted. The greatest care is taken during the manufacturing of these valuable assets to ensure no excess bending and torsion forces break or bend the components of the umbilical beyond their operational limits.  

Due to their long and flexible nature, the installation of umbilicals is challenging offshore, passing from the fabrication facility, offloading onto the vessel, transport to the installation site and final installation to the seabed. Complicate this installation process even more with adverse weather conditions common offshore, and it is easy to see why the ultimate owner of the umbilical, the operator of the field, is determined to ensure that its valuable asset is maintained properly during its entire installation journey.  

With all the time and effort that goes into planning a subsea oil and gas field, not everything can be foreseen at the start. During the redevelopment of a large subsea field, a major energy operator encountered a delay in the delivery of the FPSO. Their careful planning was disrupted. With lead times often of years, the dynamic umbilicals were already being manufactured, and their installation could not be delayed. The only choice was to wet-store the umbilicals on the seabed until the FPSO arrived several months later. The operator, therefore, required the condition of its critical umbilicals to be monitored during the entire installation process and turned to C-Kore for help.  

Innovative technological solutions. The company provided the solution, an autonomous, battery-powered testing tool that monitors the condition of the umbilical on a set schedule, the cable monitor. The testing tools were assembled and tested before dispatch from their production facility near York, UK. As the units are designed to be simple to use, no C-Kore personnel were required to accompany the units, greatly reducing operational costs. An on-line, personalized training course is provided for each order, and extra support services, such as procedure and report writing, are also available.  

By installing the cable monitor units on the umbilical at the manufacturer’s facility, the insulation resistance and continuity of the umbilical were recorded at set time intervals during the entire installation without interruptions, and without any additional specialized personnel. At the end of several months of wet-storage, the test data recorded by the tools proved the good working condition of the umbilicals. When the FPSO finally arrived on site, there was no delay in hooking up the pre-laid umbilicals.  

Satisfying international standards. In the past, installation contractors reserved considerable time in their schedules to monitor the condition of umbilicals during their deployment campaigns, guided by the international standards ISO 13628-5/API17E. The standards advise comprehensive monitoring at all stages of the installation, covering transport, first end over-boarding and pull-in, touchdown during the lay, and any changes in the performance of the umbilical cores are identified as they happen, so steps can be taken to prevent further deterioration and mitigate further damage.  

Following these standards, installation contractors must procure the appropriate equipment and personnel for monitoring of the umbilicals, secure the correct permits to perform the testing, write and receive approval on the procedures, and then mobilize the equipment and personnel to both onshore and offshore locations. During the Covid pandemic, the use of specialist offshore personnel brought further complications, as personnel were subjected to often long quarantine periods and ever-changing testing requirements. 

After successfully completing the preparational challenges of procuring equipment and personnel, securing the permits, approving procedures, and mobilizing, the operational challenges start. Following the ISO 13628-5 standards, while offloading the umbilical onto the installation vessel, the conductor electrical continuity shall be monitored at a specified sampling frequency, comparing the value to the factory acceptance test (FAT) values of the umbilical. The continuity is often measured using manual test equipment that must be hooked up into the electrical lines of the umbilical.  

For infield umbilicals with subsea wet-mate connectors on both ends, the proper installation of a continuity tester is challenging and time-consuming, connecting the individual test lines to the individual pins of each connector. The testing equipment must also be well-secured, so as not to move and give false readings while the umbilical is constantly moving during the offloading process.  

According to the standards, upon completion of the umbilical load-out, both the conductor continuity and insulation resistance should be checked. The insulation resistance measurement is often also measured with manual equipment using high voltages. The added risk of high voltages to personnel and equipment must be carefully monitored, using correct procedures. The testing area is roped off, limiting personnel access, and sensitive electronic equipment (such as the continuity test equipment) is removed.  

Offshore installation. Once the umbilical is offloaded and arrives at the installation site offshore, the laying of it begins. During this process, the conductor resistance is again monitored, according to the standards. For the installation contractor, time must again be taken to install the manual continuity tester to each individual conductor of the umbilical. This testing equipment is normally installed on the “second end” of the umbilical. This is the second-end to pass into the water during installation, allowing the installation contractor to monitor the umbilical while the first end is submerged in the water, and the second end is still onboard the deck of the vessel.  

However, just before the second end is submerged, all manual testing equipment must be removed, because it simply cannot get wet. This puts the installation contractor in a precarious position. They can no longer monitor the condition of the umbilical, when they are lowering the second end through the water column to land it on the seabed. This gives them a “blind spot” in their data at a particularly critical and hazardous point in the installation process.  

Upon landing the umbilical on the seabed, standards state that the continuity and the insulation resistance should be checked before hooking it up into the system. This creates another challenge for installation contractors—how to perform these tests? In shallow waters, a down-line may be chosen, which is essentially a long extension cord connecting topside manual test equipment to the components on the seabed. The deployment of a down-line is very time-consuming. It can take hours or even a full shift to deploy, and weather conditions also limit their deployment window.  

The condition of the down-line is also critical, as any faults in a down-line will greatly affect measurements taken. For deeper waters, the continuity and insulation resistance check is often just not done, due to the extreme difficulty in performing the measurements, as down-lines are not practical in deeper waters. These critical values, however, are needed to confirm the condition of the umbilical after the installation process, which often marks the handover of the umbilical from the installation contractor to the operator.  

Installation challenges. Some installation contractors will choose to skip the post lay test and only test the continuity and insulation resistance, once the umbilical is hooked up into the system. This introduces added complexities, as some parts of the system contain sensitive electronic equipment, such as subsea control modules (SCMs) that cannot be subjected to high-voltage tests without irrevocable damage.  

The use of standard manual testing equipment for electrical continuity tests and insulation resistance tests has additional drawbacks. The values obtained are highly dependent on the personnel performing the tests. Have they been trained properly? Are they using the equipment correctly, and are they following the test procedure?  

Weather conditions also affect the readings. A rainy day will give very different readings to measurements taken in dry conditions. This makes it extremely difficult to compare values from one test to another. When erroneous values are noted, is this due to operator error? Or are the weather conditions affecting the measurements? Or has something happened to the umbilical, where the installation must stop? All of these uncertainties delay the installation, as the anomalies must be investigated before proceeding.  

Solving complex issues. In 2015, C-Kore engineers started to address these challenges, when they brought their patented commercial cable monitor test tool to the subsea market. The cable monitor is battery-powered and automatically measures electrical insulation resistance and continuity in one unit. It is configured to run a series of tests to a preset schedule and delivers the absolute consistency of testing necessary to identify changes in electrical characteristics, irrespective of the changing environmental conditions the umbilical experiences during deployment.  

The cable monitor is capable of subsea operation down to 3,000 meters of seawater (msw) and can be deployed, fitted to the connectors on the umbilical termination assembly on the second end. Its use of a very low test voltage makes cable monitor the ideal solution for installers needing to complete the post-hook-up test requirements of the ISO/API standards. This is when sensitive electronics in the subsea control modules at the far end of an in-field umbilical could potentially be put at risk by the use of other test methods with down-lines lowered from the installation vessel. 

Two years after launching the cable monitor, C-Kore added subsea time domain reflectometer (TDR) to their rental armory, a device capable of localizing faults in electrical lines. TDR is like radar. It involves detecting reflections from a transmitted signal and using a time-of-flight calibration to determine the distance to objects or features of interest. In the case of TDR, an electrical pulse is applied to one end of a cable, and the TDR unit records a trace of the reflections received from various features (short-circuits, open circuits, splices, connectors) that the pulse meets as it travels down the wires. With knowledge of the speed that a signal travels down the cable, the time delay between the pulse leaving the TDR unit, and reflections being received, can be converted into a distance to the fault. 

In the case of electrical fault location on a subsea field, using a TDR is best done by comparing a reflection trace from the suspected faulty cable with that from a healthy twin, or twins. This is a major reason for taking baseline TDR traces of newly installed umbilicals. The baselining TDR traces are invaluable in helping to locate faults that may occur at a later date. 

The C-Kore Subsea TDR software makes this process very straightforward by enabling multiple traces to be stacked on top of one another so that any differences are immediately obvious. The point where a reflection trace from a faulty cable diverges from the stack of traces from its healthy twins can be the smoking gun that identifies the location of the fault or degradation.  

Following the launch of the subsea TDR, the company introduced the pressure monitor, a battery-powered transducer and datalogger to monitor the pressure in the umbilical lines during installation. Then, in 2022, the launch of their optical TDR meant that C-Kore could provide rental test tool solutions to monitor all of the functional components in a typical subsea umbilical. The design of the subsea OTDR is based on the company’s design philosophy of simplifying the process of subsea testing for their customers.  

The battery-powered units are programmed ahead of time to run a test sequence for up to 12 fibers. As the unit is automated, specialized personnel are no longer needed to accompany the unit offshore. The wealth of information is data-logged in the unit’s internal memory and can be reviewed by the client’s engineers or sent back to the C-Kore offices for detailed analysis. As with the subsea TDR, C-Kore’s proprietary software program allows different traces to be laid on top of each other, which helps fault-finding operations to pinpoint the location of faults.  

To complete its suite of tools for umbilical installation monitoring, the company has launched its topside wireless router to the subsea market this year. This small, versatile unit enables the collection of data from multiple cable monitors from a safe and dry location on the vessel. Deck personnel no longer need to access the umbilical termination on the reeler/carousel to obtain data, improving the safety of back-deck operations.  

Using the company’s suite of tools on their installation campaigns, operators and installation contractors simplify their subsea testing processes. By installing the C-Kore tools at the umbilical manufacturer’s facility upon completion of the FAT, the units gather a baseline reading directly related to the umbilical FAT readings to monitor how values may vary during the entire installation process. With the time-stamped data, any changes in values can be directly correlated to the handling of the umbilical, Fig. 2. 

Fig. 2. Suite of subsea testing tools.

The company’s tools are then set to monitor the umbilical at set intervals, from off-spooling to transport to installation, even through to a potential wet-storage period, when the umbilicals could be stored subsea for months before hooking up into the final system. During this whole period, the units continue to monitor the condition of the umbilical without any human intervention and without having to stop the installation process.  

The most visible benefit is the elimination of the “blind spot” in monitoring, when the second end of the umbilical is submerged. With the units already installed on the UTA, they continue to monitor the condition of the umbilical while the second end is lowered through the water column, down to the seabed. Now, once the second end of an infield umbilical touches down on the seabed, it only takes a few minutes to check the condition of the umbilical.  

The on-site ROV simply flies over to the UTA, flashes it lights at the C-Kore unit to trigger a test, and within minutes, the insulation resistance and continuity values are data-logged and shown on the display, visible to the ROV crew via the ROV camera. Trying to confirm the condition of the umbilical with traditional manual testing equipment, such as testing via topside equipment and deploying a downline, would take hours, so the time-savings are significant. 

Case study. The company’s comprehensive capabilities were quickly put to the test in September 2022 by an operator and its installer during the lay of a 16-km in-field umbilical in 1,500 msw in the Gulf of Mexico. Two cable monitors configured with 8-way wet-mate plugs were installed on the power and signal connectors on the second end umbilical termination. They were set up prior to dispatch from the UK to test the insulation resistance between cores and between each core and earth, and to measure the continuity of each conductor pair through a loop-cap installed at the far end, Fig. 3. 

Fig. 3. A cable monitor unit installed on umbilical UTA.

Pressure monitors were mounted in a multi, quick-connect plate on a Cobra head to enable continuous measurement of control fluid and chemical pressures, when each system was subjected to a 15-kpsi test over a 4-hr hold period. The installer was able to monitor for any lapse in the test pressures in real time, by using the ROV camera to observe a subsea display connected to the two pressure monitors, which also data-logged all the readings for subsequent trending and reporting. 

Subsea optical time domain reflectometers were fitted to each of the fiber optic, rolling seal connectors on the umbilical termination and were configured to test the eight fibers in each connector in turn. The OTDR test was triggered by the ROV flashing its lights three times, initiating the unit to run through its pre-programmed series of optical tests at 1,310 nm and 1,550 nm wavelengths. 

Value added. The combination of C-Kore technologies deployed on this mission provided the installer and the end-user with a clear picture of the integrity of the electrical, optical, hydraulic and chemical services in the new umbilical. Fortunately, for all the parties involved, the tests and data collected showed that the installation had been conducted successfully, and no issues were detected.  

The company’s suite of fully automated subsea testing tools is becoming the turn-to solution for a quick and easy route to compliance with the requirements of the ISO/API standards. 

C-Kore’s service and state-of-the-art equipment is changing the way installation contractors and energy operators work. The innovative tools reduce the required vessel time during subsea testing, saving operators money, while also reducing the carbon footprint of offshore operations, and at the same time providing high-quality data of the umbilical’s condition.  

About the Authors
Cynthia Pikaar
C-Kore Systems
Cynthia Pikaar is sales and marketing director for C-Kore Systems. Before joining C-Kore, she worked on a variety of cable projects, initially designing cables and umbilicals then moving to more customer facing roles in project and sales management. Her current role leading the sales team at C-Kore allows her to bring years of experience with cables into the oil and gas industry, understanding complex operational challenges and translating these into effective monitoring solutions. Ms. Pikaar is a mechanical engineer with a background in the design of cables and umbilicals. She studied mechanical engineering in the U.S. and then at the master’s level in the Netherlands
Related Articles
Connect with World Oil
Connect with World Oil, the upstream industry's most trusted source of forecast data, industry trends, and insights into operational and technological advances.