Measuring mooring tension
Seattle-based Measurement Technology NW announced successful implementation of its running line tensiometer (RLT) technology with a Samson synthetic rope in a Gulf of Mexico offshore mooring monitoring project engineered by Delmar Systems late August. This implementation is MTNW's first use of tension measurement technology with 2in+ synthetic ropes.
Delmar had been contracted to moor an offshore supply vessel to a major offshore platform in the US Gulf. The OSV, deployed as a support vessel while dive operations are conducted, is using a three-point mooring system consisting of two stern hawser lines attached to the platform and a bow mooring line attached to a preset suction pile foundation in 2900ft of water. The mooring system had to be as robust as possible while still maintaining ease of handling and rigging by the vessel crew.
To achieve a higher maximum breaking load on the OSV bow mooring line while maintaining deck maneuverability, Delmar chose Samson's AmSteel-Blue HMPE rope made of high modulus polypropylene as the bow winch line. An MTNW RL-20175K running line tensiometer provided tension measurement for the bow line. During the design phase of the project, MTNW thoroughly tested and calibrated the RLT using the specified 21/4in AmSteel-Blue rope.
‘This is MTNWs first use of an RLT to measure tension in a major synthetic mooring line of this large diameter,' noted the company's managing director Tom Rezanka. ‘Our RLTs are more commonly used to measure the tension of wire rope, but synthetic lines have different mechanical characteristics under load. We were able to collaborate closely with the R&D engineers at Samson. The monitoring system was fully tested, calibrated and witnessed on an ABS-certified test bed with the resulting accuracy identical to wire rope applications. The trend in mooring is lighter and stronger, which will require increased use of synthetic ropes and new, modern technologies to monitor them. Our sensors and systems are proven to work with any lines.'
Delmar Systems engineer Dillon Shuler said: ‘Both the AmSteel-Blue winch line and MTNW's RLT have been working flawlessly together and have played a vital role in the success of the project.'
Rezanka added that his company's RLTs are being used more frequently for mooring monitoring because their modern design provides a rapidly deployable solution for retrofitting existing winches. ‘We can deploy on virtually any winch, with an installation time measured in hours, not weeks or months.'
FPSO personnel on the move
This summer's transfer of North Sea personnel from vessel-to-FPSO using a heavecompensated marine walk-to-work system has been hailed as a world first by Offshore Solutions. During July and August an Offshore Access System (OAS) – the company's patented 20m hydraulically operated telescopic gangway designed to operate in 2.5m significant wave height – mounted on the MS Stril Explorersuccessfully transferred personnel to and from Shell Expro's Anasuria FPSO with no safety incidents.
The FPSO was located 175km east of Aberdeen, and the project was completed in less than seven weeks from initial client contact. Some 24 operational connections were made in that time, facilitating 294 individual crossings, even while Stril Explorer (chartered by SeaHold Geoships) was carrying out diving activities.
‘The capability to safely transfer personnel from a PSV [platform supply vessel] or support vessel to FPSOs opens up a much broader range of project and maintenance opportunities for many North Sea oil and gas operators,' said Lindsay Young, managing director of Offshore Solutions, a joint venture between Amec and Cofely Nederland.
‘The OAS used on this contract was also the first one incorporating the freestanding modification. The free-standing version retains all the safety and operational features of the original system, with the variation that it is mounted on a skid. This enables the OAS to be quickly installed on the host vessel, making short-term hires much more economically attractive.
‘Up to now we have safely transferred more than 90,000 personnel to fixed platforms. With this contract we have now taken several more steps forward in demonstrating that marine access works. We have proven we can install our freestanding self-contained OAS quickly on a vessel, connect to platforms or FPSOs using a variety of options and mobilise rapidly for short-term hires, which are forming an everincreasing percentage of our enquiries.'
Allan Syme, project manager for the Anasuria Support Vessel Project, said: ‘Offshore Solutions worked with us over a very short timescale to provide a gangway for the first trial of a walk-to-work solution between a DP vessel and a turret moored FPSO to support an air diving campaign and shutdown. The equipment proved reliable in service and as a proof of concept the exercise was a success. We will certainly be keeping this option in our "tool kit" for the future.'
Downed platform recovery project completed
Oil spill response and environmental solutions provider American Pollution Control (Ampol) recently completed a platform recovery project in Amelia, Louisiana.
From planning to implementation, the total project took approximately five years and included lifting the platform and remediating hydrocarbons and hydrogen sulfide on the recovered platform that had been trapped beneath 100ft of mud, reported Ampol CEO Kirk Headley. The cleaning and remediation processes were completed by air from man lifts and subsequently the platform was deemed environmentally safe for recycling.
‘We take safety seriously and spend countless hours training our employees to be prepared for jobs of this nature,' said Headley. ‘Our crew worked in very hazardous conditions to complete this project in a safe and successful manner.'
Ampol specializes in nearshore and offshore emergency response and hazardous waste remediation for oil and gas operators, industrial companies and government agencies and its service offerings include oil spill response, tank cleaning, confined space entry services, naturally occurring radioactive material (NORM) treatment and storage, lead and asbestos abatement services, hazardous material emergency cleanup, soil remediation, demolition services and marine transportation.
Riser design software upgrade
MCS Kenny has launched Version 8 of its industryleading Flexcom design and analysis software, first introduced nearly 30 years ago. Designed to boost confidence in deepwater subsea engineering design and help tackle the increasingly complex and demanding design requirements associated with multi-case extreme and fatigue seastate loading conditions, the new release's benefits include:
Patrick Scully, general manager of MCS Kenny's software division, explained: ‘We created Flexcom V8 to deliver a step-change in how riser engineering design and analysis is performed. The enhancements provided by this new version lead to a better design that supports the industry's significant focus on improved process safety, better predictability, and greater knowledge of utilisation and integrity during operations.'
Erosion protection work is now under way around the first Russian Arctic shelf fixed oil production platform, Prirazlomnaya, under a E50 million contract awarded to Tideway.
The DP2 fallpipe vessel Seahorse was drafted in from another Gazprom project, the Nord Stream gas pipelines in the Baltic (Read "How Nord Stream braved the baltic"), to place the bulk of the 100,000t stone fill required for this ice-resistant structure in 20m of water on the Pechora Sea shelf. The operation was expected to take more than 40 days.
Designed by Morneftegazproekt, the longmooted Prirazlomnaya platform comprises the upgraded 14,000t former production deck of the UK North Sea's decommissioned Hutton TLP placed on a 126m x 126m concrete caisson built at the Sevmash shipyard in Severodvinsk.
The platform, with an unballasted weight of 117,000t, is pictured at the start of its two-week tow from the shipyard to location. Drilling of the first of its production wells – 40 wells in all are planned – is scheduled by the end of the year.