Global demand for floating hardware continues apace. David Morgan and Meg Chesshyre review recent support & supply sector initiatives and innovations targeting offshore platforms and rigs.
Drilling riser departure
A high pressure marine riser system ordered by Apache North Sea from Aquaterra Energy and Oil States is being hailed as a ‘world first’ in terms of its connections and operation.
The 10,000psi-rated, full-bore drilling riser system, complete with H4 compatible subsea connector, will be deployed during Apache’s 2011 drilling program as it develops the Bacchus field in the North Sea, drilling three subsea wells from the Rowan Gorilla VII jackup rig. Apache drilling manager Brett McIntyre said the Aquaterra/Oil States system had emerged from an extensive competitive tender process with clear technical advantages and was commercially attractive. ‘We look forward to being able to use this world’s first, full bore 10k Merlin riser connection next year,’ added McIntyre.
According to Norwich-based engineering company Aquaterra, the Merlin connector developed by Oil States Industries (UK) for this work represents a major advance from current full bore risers which rely on flanged connections at this pressure. ‘This change to a weld on premium connector brings 10,000psi risers into line with other jackup riser systems, which almost universally avoid the technical and operational disadvantages associated with flanged connections,’ noted Aquaterra director James Lamder.
The Merlin connector is easy to handle and install, significantly increases running speed and improves the efficiency of operations when compared with flanged alternatives, explained Lamder. He added: ‘The development of a full bore 10,000psi Merlin connector, and our partnership with Oil States to bring it to the market, allows the handling and use of these systems to become a standard rig operation, rather than a unique handling challenge as experienced with flanged systems. This contract marks a step change in the technology available for drilling high pressure subsea wells from a jackup. This technology advance is a very big deal.’
West Atlas readied for removal
Sea Trucks’ offshore construction vessel Jascon 25 has started work on the removal of West Atlas, the Seadrill jackup rig written off following last year’s blowout and subsequent fire on PTTEP Australasia’s Montara wellhead platform in the Timor Sea (OE December 2009).
Expected to take around three months, the workscope for partners Sea Trucks Australia and Svitzer Salvage Australasia includes cleaning and removing debris from the rig as well as the cantilever drill floor which is extended over the wellhead platform, followed by the jacking down of the rig and subsequent towing to Singapore.
The multipurpose DP3 Jascon 25 is no stranger to Australian waters, having been deployed on the recent BHP Pyrenees field installation for 10 months. Specifically for the West Atlas job, where it will serve as the primary support vessel in the removal operation, an hydraulically operated, telescoping access gangway has been installed for the safe transfer of personnel to and from the rig.
Sea Trucks president and CEO Jacques Roomans said this ‘intelligent’ gangway, combined with the Jascon 25’s 800t high access crane capacity and its DP3 system’s stationkeeping redundancy, ‘all add up to provide the best available facilities for this challenging project’.
Concentric CT boat spooling
To maximise production from the Ravenspurn North ST-3 platform in the Southern North Sea, BP is rejuvenating its 14 wells using concentric coiled tubing (CT) to vacuum out any obstructions and debris, and improving the well completion design with high integrity liners. However, the operation required more than 5km of concentric CT for each well which, along with the support materials, would have placed an enormous strain on the normally unmanned wellhead platform and its equipment.
The CT equipment for example weighed 210t while the platform crane has a lifting capacity of just 12t.
Faced with this major constraint, a team from Atkins’ London and Aberdeen offices worked with BP and oilfield services provider BJ Services to adapt an existing technique developed by BJ to spool CT from a supply vessel onto a fixed platform without the need for heavy lifts. This technique has been used by BJ in the past for conventional CT; however this is the first time it has been used to deploy concentric CT from a vessel on to a fixed platform.
Atkins reviewed this approach, carried out checks on the capacity of the jacket structure and confirmed that all scenarios were considered in the design of the operation. For example, at a location where the design wave height is 18.5m, waves more than 10m high are routine and tidal currents exceed 1m/s, the well equipment was designed to have weak points to mitigate the risk of the supply vessel damaging the platform through loss of control. Using a detailed computer model of the platform, which Atkins uses to manage its integrity, the team was able to ensure all safety checks were completed efficiently.
Vivian Zhao, Atkins project manager, commented: ‘We have looked after BP’s 25 southern gas assets for the last ten years and because we maintain the platforms’ analysis models as part of our integrity management role, we were able to carry out meticulous safety checks at all points of this challenging process. There was a real appetite from everyone involved to investigate and develop new methods which resulted in great success all round. The project effectively boat spooled more than 17,000ft of concentric coiled tubing and has been hailed the world’s first of its kind.’
BP well intervention engineer Ann Davies added: ‘This project is extremely important to the future of the Ravenspurn field, and performing heavy duty work on a small unmanned installation comes with many challenges. Getting the concentric coiled tubing and associated equipment safely onboard is vital in gaining access to these wells.’
MOPUstor mark two
The deck of the industry’s second MOPUstor – mobile offshore production and storage – unit was on its way to Norway last month following loadout from the Topaz Fabrication & Construction yard in Abu Dhabi.
The jackup structure’s hull and topsides, weighing 12,400t at loadout, were fabricated by Topaz under a $75 million subcontract to SBM, which is providing the GustoMSC-designed MOPUstor on a leaseoperate basis for operator Talisman Energy Norge’s redevelopment of the Yme field (OE September 2007). The lease is for five years, with options for up to a further 10 years.
The unit was loaded out onto Dockwise’s Mighty Servant 1 for the 5000km trip to Bergen Group’s Rosenberg yard in Norway where the legs will be installed and outfitting completed. This development follows some 12 years after commissioning of the first MOPUstor, which continues to produce for Dong on the Siri oil field in the Danish North Sea.
Targeting fields with no direct access to pipeline infrastructure in water depths and environments unsuitable for FPSO deployment, the MOPUstor design consists of a steel storage tank supported directly on the seabed, and a barge type platform supported by tubular legs with its own hydraulic cylinder type jacking systems.
The Yme field, in Egersund Basin blocks 9/2 and 9/5, was discovered by Statoil in 1985 and first came into production in 1996 using a leased jackup with production and drilling capability. It was decommissioned and abandoned in 2001. Now Talisman is starting up production again and has built into the new facilities’ design the capability to become a hub for several other interesting structures with potential identified in the Yme area and any new finds.
Yme consists of two oil fields – Beta and Gamma – 12km apart and in water depths of 77m and 93m respectively. Low reservoir pressure necessitates the use of electrical submersible pumps. The fields already have new wells and a complete subsea installation in place. The MOPUstor will be placed on Gamma with a pipeline to Beta and all drilling conductors and risers collected into the structure’s 103m high caisson. The caisson and 300,000 barrel storage tank were installed prior to the topside production facility’s arrival to allow pre-drilling of the Gamma wells.
Bill Bayliss, COO of Topaz Engineering, believes Yme’s MOPUstor may be the single largest offshore unit ever built in the Middle East. With the Abu Dhabi facility’s workforce peaking at 1400, project execution involved some seven million man-hours and took more than two years, during which time no lost time incidents were reported.
Cascade riser system goes in
Installation of the five free-standing hybrid risers (FSHRs) in the Gulf of Mexico ultra-deeps for Petrobras America’s Cascade-Chinook development is reported to have gone smoothly – and with ‘zero HSE recordable’ – thanks to the combined efforts of lead contractor Technip’s flagship construction vessels Deep Blue and Deep Pioneer and Jumbo Offshore’s DP2 heavy lift vessel Fairplayer.
At 2500m water depth, these are the deepest risers of their type to be deployed to date. Having transported the five buoyancy cans from Technip’s Pori yard in Finland, Fairplayer met up with the other vessels at location. In an installation sequence coordinated by Technip and assisted by placing key members of its offshore construction team onboard Fairplayer, Deep Blue started the proceedings by deploying the riser in its entirety.
Fairplayer then moved in for a ‘wet handshake’, lifting the 2300m riser with its fore crane and placing it in a hang-off structure for connection to the buoyancy can. The whole assembly was then overboarded and lowered safely through the splash zone. For Jumbo Offshore, which sees this project as a significant milestone in its development as a specialized offshore heavy lift contractor, the 700t-plus load marked its heaviest offshore lift to date. After lowering the assembly to 200m, Technip made the connection between the riser and its foundation on the seabed in 2500m of water.
Finishing touches for Ekofisk ‘jacktel’
Master Marine’s newbuild DP2 jackup – currently known as L205 – is undergoing hookup and final commissioning at Nymo’s yard in Eydehavn, Norway before starting an accommodation assignment with ConocoPhillips on Ekofisk. To be formally named Haven before delivery from Nymo this December, it will on completion be towed to the Ekofisk field to serve as an accommodation ‘jacktel’ under a three-year contract with options for extension.
With 447 single cabins, the vessel will be the North Sea’s largest jackup accommodation unit. It is being customized and outfitted to meet the operator’s and the Norwegian authorities’ requirements including being able to withstand a 10,000 year wave. Since ConocoPhillips placed the contract for the unit in October 2008, Master Marine has worked closely with the oil major to realize this significant project (OE April 2009).
The vessel has undergone extensive modifications from the original design. It was initially built in accordance with a specification to transport and install heavy structures offshore. Additional quarters modules, a new crane, modified helideck, helifuel system, lifeboats, additional office module and the add-on footings are now being installed in Eydehavn. Master Marine says that the newbuild represents a positive turn in a volatile period for the Norwegian offshore supplier industry. The project has secured business for a number of subcontractors and secured jobs in the industry.
The Haven is the first of two innovative jackup construction vessels ordered by Master Marine from the then Labroy shipyard (now the Drydocks World, Graha facility) on Indonesia’s Batam island in May 2007. The L205 keel was laid on 29 May 2008, and it was launched on 16 January 2010. The vessel, with a length of 111.8m, breadth of 50m and loaded draught of 7.4m, was transported to Norway this summer on the Dockwise heavylift vessel Treasure. Owner-furnished equipment includes cranes from Huisman, generators, switchboards, electrical motors and transformers from ABB, a Kongsberg DP2 system, Mitab (Mitsubishi Volvo Penta) main engines and Schottel azimuth propellers.
Meanwhile, the plan is for sister newbuild L206 to be completed as originally intended – a self propelled jack-up construction vessel. To be delivered early in 2011 and named Nora, it will be capable of installing jackets by tandem lift (1500t revolving capacity) and installing topsides by either skidding (7200t capacity) or tandem lifting (1500t capacity).
The vessel has already been contracted by Scira Energy (a joint venture between Statoil and Stakraft) to install two substations and 88 wind turbines for the Sheringham Shoal windfarm offshore the UK next summer.
Offshore installation is expected to take 210 days. The vessel will be able to transport the two 1100t substations simultaneously.
Fairlead ‘first’ for Captain
Aberdeen-based RBG recently provided rigid-hulled inflation boat (RHIB) dive services and project support for Acergy during the removal and replacement of one of the fairleads from Chevron’s Captain FPSO. Under a contract worth approximately £400,000, RBG’s combined activities included diving, installation of subsea rigging and ROV services, deployed from the Acergy-chartered vessel Far Saga.
Paul Jamieson, Chevron Upstream Europe subsea engineering coordinator, commented: ‘Many thought it couldn’t be done following initial anomaly identification during ROV inspection back in April 2009; however the team managed to engineer, plan and execute multiple vesselbased ROV, diving and FPSO orientated campaigns to get us to this point. All activities have been completed injury free and without impact to production.’ OE
Subscribe
