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.
PIKAAR, C-Kore Systems
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.
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.
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
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.
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, pull-in and touchdown during lay. 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
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.
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.
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.
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.
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
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 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
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.
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 (10,000 feet) 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.
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
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.
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.
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 its 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 (5,000 feet) 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.
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
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. WO
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.