Advancing Monitoring Requires Advanced Oversight

By Louise Ledgard
Friday, October 25, 2013
Image courtesy of Bristow Helicopter.

Recent severe storms in the U.K. North Sea have resulted in a number of floating production, storage and offloading vessels (FPSOs) being shut down in order to assess and repair the damage caused. Notwithstanding the possible safety implications for operations crew, oil and gas majors are facing weeks, if not months without a critical asset which in turn, is having a significant impact on future production.
 

The design and operation of an FPSO in remote locations requires detailed information on the structural response of the vessel within the local environment offshore.  Monitoring of critical components including the risers, hull and mooring lines simultaneously with the local environmental forcing of waves, wind and currents at the site location, provides a valuable insight into the performance and possible extension of the integrity life of the asset.  As new technology is introduced, riser design becomes more sophisticated and extension of design life is required. Also, it becomes increasingly important to monitor an asset’s performance to assist with operational decisions, forensic investigation of marine incidents and the evaluation of design codes.

Over the last few years, an increase in the number of offshore incidents related to FPSOs in the North Sea during extreme storm conditions has resulted in focused attention on the verification of design codes and a review of inspection procedures. With an average mooring failure projected at 8.8 years for an FPSO in the North Sea and the consequential damage this could have on the riser, a number of Joint Industry Partnership (JIP) initiatives have concluded that the management and audit of the FPSO integrity is required. Furthermore, indicative costs resulting in the remediation activities required for a single mooring line alone have been estimated at $3.2m for a North Sea FPSO and many companies believe that insurance premiums are likely to rise due to the number of claims now being made.

As an attractive and flexible option which eliminates the need to lay expensive long-distance pipelines, the number of FPSOs being put into service in remote locations is rising. As such, the complexities of understanding the performance of the vessel in given sea-states and the interaction of the FPSO with the subsea infrastructure, becomes imperative.

Marine monitoring systems have primarily been used to provide real-time information for operational support during production with typical examples of its use being: vessel position (particularly in storm conditions); information on the metocean conditions during operation; production riser tension, buoyancy and stroke and mooring line tension for failure detection.

Furthermore, monitoring systems provide information to verify the design of the asset and provide input into fatigue calculations for mooring lines and risers. Currently, finite mathematical modeling is carried out when designing the riser configuration for the FPSO, but what is often lacking is the robust data to validate the actual local environmental conditions.  Feeding this data into the design process can help to validate the accuracy of the modeling tools being used and reduce uncertainty.

The standard sensors and parameters that should be measured within the system include:

•    Meteorological – the monitoring of the meteorological conditions offshore is critical to ensuring the safe operation of the asset.  In 1981, the Civil Aviation Authority (CAA) and the Helideck Certification Agency (HCA) introduced the CAP 437 standard for the U.K. Continental Shelf and currently recommends that meteorological parameters and motion of the helideck are measured for an FPSO.  Such parameters provide critical operational information which is sent back to shore so that companies planning any crew changes or helicopter operations are fully aware of the weather status on the vessel before dispatch.  Safety of employees is of the upmost importance, therefore companies want to ensure safe take-off and landing conditions

•    Wave monitoring
– wave induced loads are the main source of fatigue for FPSO design and wave height is a significant factor to consider for the design of the risers, as well as assessment of mooring fatigue life and hull integrity.  Recording the extreme events in storm conditions also provides valuable input to the marine forensic investigation of any offshore incident

•    Ocean current – Surface currents can impact any offloading operations from the FPSO to the shuttle tankers and influence the response of the risers and moorings, resulting in fatigue loads 

•    Position and attitude – measurement of the position of the FPSO is essential in storm periods to understand the vessel response to environmental forcing and the coupling of the resultant fatigue on risers and mooring lines.  The position of the vessel is also critical in the assessment of any marine incident

•    Riser monitoring - a detailed understanding of the environmental forcing to the FPSO combined with the riser response can aid the design process and provide the input to fatigue calculations 

•    Hull monitoring – stress induced in the deck and hull of an FPSO can be monitored using a series of long base strain gauges positioned in strategic locations on the deck and flare tower.  In addition, pressure sensors installed in the hull provide information on the vertical acceleration of the FPSO

•    Mooring line – monitoring the mooring line is challenging and there is a scarcity of long term in-situ observed data sets for mooring line tension.  For forensic engineering and validation of design codes, it is essential that mooring line tension is collected simultaneously with metocean parameters on a common time base.

Each of the components mentioned above are likely to involve a number of third party suppliers, therefore the challenge that oil and gas majors are faced with is ensuring they all integrate into one effective monitoring system, to provide a holistic approach and support the assets’ integrity management program.  Correct placement of the sensors on board the FPSO and full integration of the data within a common time base is vital.  By carefully setting up the sensor clocks and sampling frequency during the installation of sensors at strategic locations on the FPSO, companies can use the resultant data set to effectively study the coupled response of the vessel with the environmental and resultant dynamic loading on the risers and mooring lines to study fatigue.  

Monitoring of all the different parameters within this common time base can also assist with forensic investigations of marine incidents.  For example, companies want to be able to match the time the mooring line broke with the highest wave that hit the FPSO.  If the clocks on the mooring sensor are different to that of the wave sensor, forensic engineers will not necessarily marry the two together.  Instead of working in isolation, the different parameters must be fully integrated to allow the root cause of the incident to be clearly identified. 

Significant advances in technology over the last decade have meant that oil and gas majors can monitor the effect the local environmental conditions have on their critical infrastructure offshore.  Sophisticated sensors on board an FPSO can provide real time information for operational support and provide valuable input into studies on the performance of the FPSO in varying sea states.  However, to be fully effective, oil and gas companies must look at the monitoring of their critical assets holistically with the end user taking an active role in the planning and implementation of an integrated marine monitoring system.  It is vital that data is archived and stored in a common portal to allow engineers and operational teams to make the most of this valuable information. 

Only then can they feel confident that the system is indeed fit for purpose and the risks of lost production due to repair or worse, a lengthy shut-down, are minimized.



About the Author
Louise Ledgard  has a P hD in Materials Engineering and Design, a Bachelor’s Degree in Applied Physics and a Masters in Business Administration.  With over 15 years’ experience working within the offshore oil and gas sector, Louise helps clients to identify an optimum solution for their offshore operational and marine engineering requirements.

(As published in the October 2013 edition of Maritime Reporter & Engineering News - www.marinelink.com)
 

  • Louise Ledgard  has a P hD in Materials Engineering and Design, a Bachelor’s Degree in Applied Physics and a Masters in Business Administration.

    Louise Ledgard has a P hD in Materials Engineering and Design, a Bachelor’s Degree in Applied Physics and a Masters in Business Administration.

  • Measurement of wave height from FPSO using air gap sensor.

    Measurement of wave height from FPSO using air gap sensor.

  • ADCP Deployment

    ADCP Deployment

  • Louise Ledgard  has a P hD in Materials Engineering and Design, a Bachelor’s Degree in Applied Physics and a Masters in Business Administration.
  • Measurement of wave height from FPSO using air gap sensor.
  • ADCP Deployment

Maritime Today


The Maritime Industry's original and most viewed E-News Service

Maritime Reporter January 2016 Digital Edition
FREE Maritime Reporter Subscription
Latest Maritime News    rss feeds

Technology

Norbulk Selects Parker Kittiwake’s Cat Fines Test Kit

Parker Kittiwake, a leading global supplier of asset control and protection technology, has today announced a significant order of its recently launched Cat Fines

European Consortium Launches Blue Nodules Project

On 1 February a European consortium launched a new Horizon 2020 project: Blue Nodules. This project addresses the challenge of creating a viable and sustainable

Seafarers help Sought to Improve Onboard Design

The Nautical Institute and CIRM (the principal international association for marine electronics companies) today launched a joint initiative to improve the usability

Environmental

Sardines Boost Murmansk Port Turnover

In January 2016 turnover of the Murmansk Marine Fishing Port reached 22 thousand tons of cargo, including 15 thousand tons of fish. This is higher than last year,

VPS Raises Concerns Over Revised Rules for Fuels

Veritas Petroleum Services (VPS) expressed reservations about some of the proposed revisions to the international ISO 8217 specifications of marine fuels. Areas

China to Enforce Low Sulphur ECA in Yangtze River Delta

Vessels calling ports in China’s Yangtze River Delta, including Shanghai, will be required to burn low sulphur fuel while at berth from April 1 this year.   China’s

News

First Women's Expedition to the Arctic

Company "MyArctic-expeditions" organize the first women's expedition to the Arctic Ocean. The expedition will start on March 5 in the capital of the Nenets Autonomous

Topaz Responder Saves Refugee Migrants

Topaz Energy and Marine has emerged as an unlikely player in the effort to save refugee migrants risking their lives on the sea crossing from Turkey to Greece’s islands in order to reach Europe.

Sardines Boost Murmansk Port Turnover

In January 2016 turnover of the Murmansk Marine Fishing Port reached 22 thousand tons of cargo, including 15 thousand tons of fish. This is higher than last year,

Maritime Safety

Topaz Responder Saves Refugee Migrants

Topaz Energy and Marine has emerged as an unlikely player in the effort to save refugee migrants risking their lives on the sea crossing from Turkey to Greece’s islands in order to reach Europe.

Antietam, McCampbell Build Relationships at IFR 2016

Ticonderoga-class guided-missile cruiser USS Antietam (CG 54) and Arleigh Burke-class guided-missile destroyer USS McCampbell (DDG 85) arrived Feb. 4 in India

Hijacked Singaporean Ship Released in Nigeria

The crew of a Singapore-registered container vessel, Safmarine Kuramo, hijacked off the Nigerian Coast earlier this week, were released unharmed on Saturday (Feb

Offshore Energy

HHI to Localise Main Equipment for Offshore Plants

Hyundai Heavy Industries and Doosan Heavy Industries Collaborate in Localizing Main Equipment for Offshore Plants   Seoul, South Korea – February 4 – Hyundai Heavy Industries (HHI),

FUGRO Wins BHP Pyrenees Contract

Fugro has been awarded a contract by BHP Billiton Petroleum Pty Ltd for the Pyrenees Phase 3 Installation Project.   The Pyrenees development is located offshore Western Australia,

Iqarus Acquires C-CHEC at Subsea Expo

Offshore and onshore health and medical solutions company Iqarus is set to acquire occupational hygiene consultancy C-CHEC to deliver a new integrated offering to global industries.

Ocean Observation

First Women's Expedition to the Arctic

Company "MyArctic-expeditions" organize the first women's expedition to the Arctic Ocean. The expedition will start on March 5 in the capital of the Nenets Autonomous

MOL Enhances CSW Service between Asia and East Coast South America

Mitsui O.S.K. Lines (MOL, President & CEO: Junichiro Ikeda) today announced the enhancement of its Asia and East Coast South America trade by merging existing

Shipping Traffic Noise Severely Affects Whale Populations

Underwater sound pollution disrupts the communication methods of killer whales and could harm their ability to locate salmon, researchers have found.   Increasing

 
 
Maritime Security Naval Architecture Navigation Offshore Oil Port Authority Salvage Ship Electronics Ship Simulators Sonar Winch
rss | archive | history | articles | privacy | contributors | top maritime news | about us | copyright | maritime magazines
maritime security news | shipbuilding news | maritime industry | shipping news | maritime reporting | workboats news | ship design | maritime business

Time taken: 0.1702 sec (6 req/sec)