Acteon S2S 8

The acteon customer magazine

V.8 05-10

InterAct meets tank control challenge at oil facility expansion in California Claxton ensures success for unusual new well slot project InterMoor pile innovation allays customer’s cost, timing and reliability concerns

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news

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built-in power

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calling for responsibility

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under pressure

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picturing the solution

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guiding principles

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meeting wind industry needs

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suction piles for thunder hawk

For further information, please contact

www.acteon.com

Paul Alcock

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T: F: W: E:

+44 1603 227019 +44 1603 774175 www.acteon.com paul.alcock@acteon.com

Š Acteon Group Ltd 2010

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RICHARD HIGHAM GROUP CHIEF EXECUTIVE, ACTEON

A recent study by Sir David King, a former UK government chief scientist, and researchers from the University of Oxford’s Smith School of Enterprise and the Environment has concluded that the world’s oil reserves have been exaggerated by up to one-third.1 King puts this down to two things: the overinflation of OPEC reserves, an issue that has been around for years, and unrealistic estimates of the amount of unconventional oil that might ultimately prove to be recoverable. According to his figures, demand for oil could outstrip supply by as soon as 2014.

Now, wherever you stand on the subject of peak oil and its timing, you will probably find it difficult to argue with another of King’s conclusions: that we must make better use of our remaining resources by improving efficiency.

Here, the former chief scientist was alluding to the efficiency with which we use energy. In fact, as our reserves fall and the cost of recovering them inevitably rises, there is a strong case for striving to improve efficiency right along the oil and gas value chains.

Efficiency and value have always been part of Acteon’s business model, as we work in exploration, field development, production and decommissioning. Central to our way of thinking is that, as a group of companies, we must make the optimum use of our available technology and link together our products and services, more often than not in the subsea arena, to maximum effect.

Individual projects and initiatives of this kind may seem a world away from the big argument concerning peak oil. However, they demonstrate a philosophy that we can all contribute to: the optimum use and conservation of increasingly valuable resources.

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Owen, N. A., Inderwildi, O. R. and King, D. A.: “The status of conventional world oil reserves – Hype or cause for concern?”

Energy Policy (2010), 38.

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You will find examples of this philosophy in every issue of S2S. This one is no exception. InterAct has helped Orchard Petroleum raise the efficiency of its production operations in California (page 8).

Seatronics provided Acergy with a remarkably efficient 3D multibeam sonar that helped to unlock the solution for a production problem experienced by DONG Energy in the North Sea (page 12).

Claxton played a key role in enhancing production from a mature field in the UK Irish Sea; this was achieved very efficiently by adding a new well slot to an existing platform (page 15). And InterMoor has improved the efficiency of installing suction piles for its customers through a series of key innovations (page 18).

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news challenging well abandonment for centrica InterAct recently completed the abandonment of an unusual well for Centrica Hydrocarbon Resources Limited in the East Irish Sea.

In 1983, observation well 110/2-7 was drilled to 1244 m in 34 m of water. It was used to monitor temperatures and pressures in the South Morecambe gas field. The well was enclosed in a bathymetric chamber, which enabled divers to gain occasional access to the various gauges in the well. This is the only known example of its type in the world. After a period of use, the well was suspended, and, in 1999, part of the chamber was removed and the remainder was left flooded.

Full abandonment after 10 years posed a series of challenges, especially as it was to be performed in winter. The well had been fitted with a surface tree, and there were concerns about the tree’s condition after having been immersed in seawater for so long. There were limited tree data and chamber design data; the condition of the tubing in the well was suspect; the exact

downhole arrangement was uncertain; and three mandrel control lines extending down into the completion string potentially affected the ability to seal the well properly.

In addition, the well pressure turned out to be 800 psi higher than expected.

If these were not challenges enough, InterAct’s solution for the abandonment involved using both a diving support vessel and a drilling rig, which led to the additional requirements of combined operations.

Stuart Wordsworth, general manager, InterAct, said, “We were faced with an uncommon well, constructed in an unusual fashion and about which there were several uncertainties.

As part of developing the abandonment programme, we carried out a scenario analysis to come up with contingency measures to deal with the various problems we thought might arise offshore.”

Roman Sitek, well engineer, Centrica Energy Upstream, added, “The safety culture

LDD off to Papua New Guinea Late in 2009, LDD secured a major contract with the Clough Ltd–Curtain Bros joint venture (CCJV) to supply specialist piling equipment and services to support Esso Highlands’ (an ExxonMobil subsidiary) Papua New Guinea liquefied natural gas project.

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LDD will install 1200-mm piles for the initial phase of two wharves and several bridge crossings over large rivers deep in the highland jungle. The in-field piling work began in February.

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The company is providing and operating all the drilling and piling equipment, which includes two pile-top drilling rigs (with compressors and pumps), S90 hydraulic hammers (supplied

by LDD’s sister company CIS) and vibratory hammers. Working in such a remote location

requires specialist project management and engineering support, and an extensive sparesand-repair package. LDD has designed hammer upending frames and a pile stability frame specially for the project’s difficult conditions.

LDD and the CCJV team have worked together to determine the critical path tooling and preparation, including the design and fabrication of large-diameter under-reaming units.

One of the challenges of the project is the lack of geotechnical investigation near many of the piles. In response, LDD has designed and built a bespoke pile-top platform to mount a Diamec® 262 rock coring drill on top of the piles to enable it to proof-core the rock socket before piling.

surrounding the project was very healthy and played a significant part in managing the technical challenges presented by this well and ensuring the operation was without accident or incident. The total engagement and professionalism of the off- and onshore teams were critical to the successful execution of the work.”

InterAct was awarded full project management of the project. As well as designing the abandonment programme, InterAct built its own abandonment team, assembled many of the services necessary to execute the work and supervised the offshore work in conjunction with Centrica’s offshore drilling representative. Several Acteon companies were subcontracted through InterAct and provided essential input to the project. Claxton provided design services and tooling for the work. OIS helped to devise and manage the marine procedures and advised on diving operations. 2H contributed riser analysis skills and brace design.

safer crane operations A new EEx-rated rig camera with best-in-class visual performance from Claxton will help rig crane operators to monitor the area beneath the crane boom, where loads can often be moved into areas invisible from the crane’s cab.

The new crane boom camera system, which is offered for drilling rig cranes and CCTV safety monitoring offshore, uses the same rugged components as Claxton’s field-proven subsea cameras but combined with high-quality, explosion-proof housings. The camera system helps crane operators to transfer loads safely, even in blind locations, and is suitable for installation on virtually any type of crane operating in any environment.

LDD has received fantastic feedback from client Woodside following the completion of 144 downhole under-reamer actuations with 100% accuracy at the Pluto site on the North West Shelf, Western Australia.

The particular challenge Woodside had to solve was how to increase the skin friction and load bearing of the 12 massive 3-m diameter drilled and grouted piles that anchor the Pluto jacket to the seabed. The solution was to cut grooves into the rock socket wall as drilling of the main 3-m holes advanced. With the pile grouted in place, the grooves would act like a giant wall or fixing plug and provide additional fixity. This is where LDD came in.

LDD designed and built two complete under-reaming units with subsea hydraulic activation systems and surface hydraulic power units (incorporating an LDD-developed monitoring system to track the opening and closing of the cutter arms downhole) mounted within the drilling system. The under-reamer also incorporated a special weak-link facility, a design requirement that ensures that the device can be withdrawn and pulled in for extraction should it get stuck open downhole.

The under-reamers have five wings each housing a specialist 12-in. tungsten carbide button rock cutter on an articulating

hydraulic arm. When normal drilling of the 3-m rock socket was under way the cutters were folded in behind the drill bit. When a groove was required, the hydraulic system powered the cutters out with more than enough force to cut the soft rock at Pluto.

The new facility will be developed on 24 acres and will house administrative, maintenance, operations and fabrications employees.

InterMoor will move its current operations from Amelia to the facility.

The facility will feature more than 2800 m2 of fabrication space, including a high-

2H Offshore Engineering Ltd is the latest Acteon company to open an office at Tern Place House in Aberdeen, UK.

The cutters extended into the rock wall to cut a groove about 175 mm beyond the main hole diameter. Once the cutters were fully extended, drilling proceeded downwards to cut a groove of about 500 mm, after which the cutters were retracted and main hole drilling proceeded to the next groove location.

Twelve grooves were cut per pile socket.

The move will enable 2H to provide a more direct service to those operators and contractors in the area that had previously worked with the company through its London office. The new office will also help 2H to develop closer ties with other Acteon companies to improve the group’s service offering in the region.

The under-reamers were loaded into the giant drilling caissons before the project and submerged subsea, where they remained for the entire drilling programme and operated with 100% reliability and function.

The 2H team will focus initially on drillingriser, completion-riser, conductor and wellhead assessments, and will be staffed by new local employees and experienced 2H staff relocated from other offices to maintain the high-quality service clients are accustomed to.

Woodside’s resident engineer and platform installation coordinator said, “The hole inspection was completed this morning and all 12 grooves are clearly defined, as per the design profile requirements. We are very pleased with the level of experience applied to designing the borehole roughening tools, and congratulate your design team on a firstclass design, which has proved reliable for the whole drilling campaign.”

State-of-the-art facility InterMoor Inc. recently celebrated the groundbreaking ceremony for its new facility in Morgan City, Louisiana, USA.

2H moves to aberdeen

tech, computer numerically controlled cutting machine, mooring equipment and capabilities; a 700-m2 wire doping area for inspecting, protecting and preparing wire rope for offshore jobs; a state-of-the-art 1900-m2 blasting and painting facility; and a 300-t crane to enhance docking services.

This capital investment will enable the company to retain more than 200 jobs and secure room for future growth.

Bowtech agreement Seatronics has bolstered its service offering in the Middle East, the Far East and the Gulf of Mexico regions following an agreement with Bowtech Products Ltd. The company will be the exclusive agent for Bowtech’s range of specialised visual inspection systems.

Bowtech is one of the world’s leading suppliers of components for the remotely operated vehicle and remote underwater intervention industries, and specialises in the design, manufacture and supply of visual inspection systems, electrical and fibre-optic connectors, fibre-optic multiplexers and slip rings for use in hazardous areas or under water to any depth.

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flawless under-reaming Commended

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news pulse scoops atp contract Pulse Structural Monitoring, Acteon’s latest business group, has been contracted by ATP Oil & Gas to supply a real-time riser monitoring system for the ATP Titan platform supporting the Telemark Hub field development in the Gulf of Mexico.

The platform is a self-contained, floating drilling and production triple-column spar structure. The monitoring system will be installed on one of the production top tension risers (TTR) and linked to a topside data acquisition system. The gathered data can be evaluated offshore or transmitted to shore on demand for further evaluation and integrity management purposes.

The system will incorporate INTEGRI™ sensors to monitor the global response of the production TTR and enable rig personnel to capture data in real time. The primary objective is to measure and quantify fatigue damage to the risers from wake-induced oscillations during high current events in real time. The monitoring system, which is fully remotely operated vehicle and diver serviceable, features INTEGRIstick® dynamic curvature sensors to measure the bending strain at the critical fatigue locations and INTEGRIpod®-HM highprecision motion loggers placed along the upper span of the riser string.

Market demand has led to the creation of Pulse, which was previously embedded in 2H Offshore, according to Pei An, head of the newly formed company. “The technology in this area has developed considerably in recent years. What was once viewed as a research and development exercise has evolved into an established commercial business. We need to be attuned to customers’ requirements in an increasingly competitive market.”

Pulse’s remit is to provide structural monitoring equipment, systems and services to the offshore industry. The group will focus on expanding the customer base and growing the business in structural monitoring, and will operate in the UK and the USA.

resounding success off brunei CIS’s first project for Brunei Shell Petroleum (BSP), installing a 30-in. conductor 7 km offshore Brunei, was a “resounding success.”

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During the installation, CIS’s technicians made up and ran the first three joints of the conductor through the rig’s rotary table. They then rigged up the hydraulic hammer and hoisted it into the rig’s derrick with another joint, before making the joint connection and lowering the whole conductor string onto the seabed.

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Once the conductor string had settled, the hammer was used to drive the pipe. Additional joints were added until the desired penetration of 94 m was attained, and then the crew cut the conductor at the required height in readiness for wellhead installation.

Liew Anchaboh, CIS offshore drilling supervisor on the Bima rig, said “There were no incidents, no non-productive time and no

health, safety or environment issues. The entire conductor installation project was a resounding success. It was a very smooth, well-planned operation, and we achieved our project time curve.”

Thorough project planning and high-quality systems and procedures, especially for servicing and maintenance of the equipment, were major contributing factors. During the preparation phase, the CIS team met BSP project staff to gather operational information and detail the operating procedures.

The team also set up the pipes and moved all the necessary equipment into position on the rig well in advance. Specialist CIS staff also performed stringent on- and offshore checks on the two S-90 hydraulic hammer packages, the pipe-handling tools and the lightweight cold-cutting systems.

“not only have we gained deck space, we have also increased our vessel availability. we are delighted with how swiftly this project has developed and the quality that is being delivered.”

BUILT-IN POWER

In less than five months, MENCK delivered a custom-designed power pack fully integrated directly into the Castoro Otto’s hull.

Photo courtesy of Saipem.

“Saipem came to us with a specific need,” recalls Jost Pokelsek, director of after-market sales at MENCK. “They wanted a better solution and said, ‘Help us to increase our vessel’s availability and save time and improve maintenance procedures too.’”

Six years ago, MENCK brought power pack building in-house.

Reducing the dependency on external providers meant that the company had greater control of the quality and performance of the heart of the hammer system. “In-house design enables us to create new products specifically for our needs and ones that can withstand the harsh conditions our equipment faces,” remarks Ulf Schmidt, senior project engineer responsible for the development of the new MHP 3200E. Having a core knowledge base built up around hydraulic power production enabled MENCK to act quickly. During a series of intensive technical discussions with Saipem, the company developed a plan for a power pack that could be installed directly into the ship’s hull. This would free valuable deck space and ensure that the vessel was always ready for hydraulic operations. In addition, running the power pack off the vessel’s power system would eliminate some diesel motors and reduce fuel use. In mid 2009, Saipem gave the project its go-ahead and the MHP 3200E was born.

Engineering and project management success Knowledge and agile thinking were invaluable to the success of this project. By putting the power pack down below, not only is valuable deck space made available but general noise levels are also reduced. The power pack is always with the vessel, which makes it more flexible in reacting to customers’ requests and increases its availability. Having an integrated power pack provides streamlined maintenance schedules and reduces downtime.

The first challenge was how to fit the power pack into the ship’s hull.

The unit had to fit through a 2.5-m wide hatch. The MENCK design team developed a modular concept that enabled large assembled parts of the power pack to fit through the opening. This sped up the overall installation by allowing some pre-assembly elsewhere.

The second major challenge was the power source. Eight electric motors run from the ship’s power plant drive pumps that produce a hydraulic fluid flow rate of 3200 L/min. The eight motors also run the water-cooling system, thus eliminating the need for a complex cooling solution.

In less than five months, MENCK designed and delivered the new power pack. The company’s unparalleled knowledge of designing and experience of building client- and project-specific solutions for offshore hydraulic power generation contributed to the quick turnaround time.

“Not only have we gained deck space, we have also increased our vessel availability,” says Dario Donelli, Saipem assets offshore equipment manager. “We are delighted with how swiftly this project has developed and the quality that is being delivered. We have upgraded our machinery and become more efficient at the same time, thanks to MENCK.”

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A diesel-hydraulic MHP 3200 power pack has been powering MENCK hammers on the Castoro Otto derrick installation and pipe-laying vessel for over 30 years. This reliable power pack was slowly becoming outdated and cumbersome in today’s increasingly streamlined and demanding installation business. The power pack needed to be removed from the deck for pipe-laying activities, which was a time-consuming process also requiring on-land storage space and different maintenance levels. Sourcing spare parts was also becoming a problem.

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Calling for responsibility A PROCESS CONTROL SYSTEM THAT AUTOMATICALLY MAKES CALLS TO PLANT OPERATORS LIES AT THE HEART OF A MAJOR OIL FACILITY EXPANSION IN CALIFORNIA. Like many smaller independent oil companies, Orchard Petroleum relies heavily on outside help when it comes to major engineering and construction projects. The expansion of the company’s South Belridge field oil processing facilities in California, USA, is a case in point.

When Orchard first approached InterAct in 2007, it was simply for assistance in assessing several possible tank vendors. However, as the relationship between the two companies developed, so did InterAct’s scope of work: ultimately, the company provided engineering, project management and site supervision services for a large part of the expansion project.

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Central to the project was the installation of six new tanks, the largest of which stores produced water before its reinjection into the reservoir.

InterAct managed all this work, beginning with a detailed review of the tank designs and ending with the final inspection process. The company’s engineers also took care of the piping system that links the new tanks. Extensive use was made of 3D modelling during the design phase to optimise the layout and, as far as possible, to avoid on-site cutting and welding, both of which would have adversely affected the quality and the cost of the job.

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As well as the new tanks, the project scope included upgrading the separation facilities and a simple gas scrubbing system, and providing a new flare, which was the first of its kind in the area.

InterAct engineers undertook a rigorous evaluation process before selecting a sonic flare that exploits the Venturi effect to produce a smokeless flame without needing to force air into the gas flow.

Jeff Hall was InterAct’s lead on the Orchard project and worked closely with Orchard’s management and field staff. He says, “InterAct’s aim throughout this project was to provide strong, committed professionals who were comfortable with all aspects of the project: contract management; logistics; cost and schedule control; safety and quality management; and the permitting process. The last area is a particular strength of InterAct. Our specialists in this area dealt with all the relevant agencies to obtain the necessary building approvals and also secured the official backing for our unusual choice of flare.”

Process control As the production stream at South Belridge contains up to 95% water, monitoring the fluid level in the 10,000-bbl water tank is essential to the smooth running of the new plant and, hence, maintaining

maximum oil production. A constant balance needs to be struck between the water entering the tank and that leaving it for reinjection into the reservoir.

What appears to be a relatively simple process-control requirement is slightly more complicated because, although oil is produced continuously, the plant is supervised for only eight hours a day, five days a week. With this in mind, Hall personally devised a control system that makes calls to members of the operations team when problems occur and the site is unmanned.

The water tank control system consists of a top-mounted ultrasonic sensor that provides an output of between 4 and 20 mA, which corresponds to a difference in the fluid level in the tank of 9 m. This variable signal is sent to a programmable logic controller (PLC), which, as the site is not connected to the grid, is powered by a 24-V solar photovoltaic array. From there, the information is routed to a PC in the plant’s control room that constantly displays the condition of the tank. Users who know the password can access this information over the Internet at any time from remote locations.

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The new oil processing facility has three oil storage tanks, each with a capacity of 750 bbl; a 750-bbl wash tank; a 1000‑bbl clarifier; and a 10,000-bbl produced water tank, which is on the far left. The size of this tank when compared with the others reflects the fact that the production stream contains up to 95% water.

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A detailed engineering case ensured Air Pollution Control District approval for the new flare, the first of its kind in the area.

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>>> The PLC is also programmed with various low and high alarm points.

If one of these is reached, the system is configured so that the PC sends an SMS text message to nominated operators’ mobile phones. In the event that the level in the tank reaches a critical high point before anybody can reach the site, the system automatically shuts down selected wells producing the largest volume of water.

Wireless links between the main PLC and the control panels (also solar powered) at two fuel manifolds activate solenoid valves to shut down the gas supply to the oil well pumps. Should the level in the tank reach a critical low point, the PLC reduces the flow of water out of the tank by reducing the running speed of up to six water reinjection pumps.

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Hall says, “The system has proved so successful that we have subsequently added level indicators to the two three-phase oil– water separators and a sensor to monitor the site’s main generator.

Again, the PLC generates text messages if alarm points are reached and, ultimately, reduces the production flow into the separators

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Remote, solar-powered control panels activate solenoid valves to shut down the gas supply to the oil well pumps if the level in the water tank reaches a critical high point.

by cutting the supply of fuel gas to the oil well pumps. We are now incorporating the gas compressor and the oil tanks into the system.

What started as a simple water tank control system has grown to encompass the whole facility, and multiple alarms trigger different text messages to the operators.”

The process control system at South Belridge epitomises the attention to detail that InterAct has brought to the project. Through its appetite for solving the numerous challenges that the project has presented, the company has ensured a facility that closely matches this highly efficient operator’s needs.

Under pressure Designing a specialist reel for a specialist hose

The 3-in. flexible pipe will be utilised during pre-commissioning of the Uruguá–Mexilhão pipeline, which Saipem is installing and commissioning for the Brazilian state oil company Petrobras. The 174-km long, 18-in. gas pipeline will link the Cidade de Santos floating production, storage and offloading vessel, which is anchored in Uruguá field in 1372 m of water, to the Mexilhão-1 gas platform (172 m water depth).

Aquatic equipment and personnel will provide assistance in precommissioning the gas pipeline, which involves cleaning, dewatering and drying the pipeline by pumping pressurised gas through it via the downline flexible pipe.

Saipem contracted DeepFlex in Houston, Texas, USA, to manufacture the flexible pipe, and, because of the unique environment and product specifications, asked Aquatic to design and fabricate an installation and storage reel, and to provide a reel drive system and tensioner for installing and recovering the flexible pipe on location; the pre-commissioning will be carried out from on board the Saipem fleet installation vessel, the multipurpose support vessel Normand Cutter.

The flexible pipe began life at the DeepFlex manufacturing facility in Manitowoc, Wisconsin, from where it was shipped, via Canada, across the Atlantic to Peterhead, UK. Once the flexible pipe arrived in Peterhead,

Aquatic took receipt and transpooled it from its transportation reel onto the newly fabricated installation and storage reel with DeepFlex personnel as witnesses.

“One of the areas we pay particular attention to when designing a reel of this type is the potential forces that are going to be exerted on it. This 6.8-m diameter reel will need to withstand the environmental conditions of the journey, such as the forces acting on it through the vessel’s motion, and the compressive forces when installing and recovering the flexible pipe from the seabed,” explains Adrian Chubb, project manager at Aquatic.

“The hose will be deployed onto the seabed from the host vessel so that it can be used to pump pressurised gas through for the initial dewatering operation, but it will still have a residual length spooled on the reel. This acts as a contingency and also assists in providing back-tension for hose control during deployment and recovery. You have to design such reels with the structural strength to survive that kind of constriction,” says Chubb.

The flexible pipe has been developed to withstand the high pressures in the deepwater Brazilian field and the product that is being pumped through it. “The flexible pipe is manufactured from a lightweight composite material, which has advantages over traditional flexible and rigid steel products,” says Brian Osterloth, project coordinator at DeepFlex. “The steel product is heavier and results in a greater top tension, whereas the composite product can be deployed from a smaller installation or service vessel. It can also be retracted and used in multiple applications.”

After the flexible pipe was transpooled, Aquatic pressure-tested it, also with DeepFlex personnel as witnesses, to make sure that it had not been damaged in transit or had its integrity compromised. Chubb says, “We also carried out a tensile pull test on a sample of the flexible pipe before the equipment was mobilised to ensure that its friction capability was sufficient for it to function with the tensioner. This test mimics the stresses the flexible pipe could be subjected to when it is deployed from the installation vessel during installation and recovery.”

Finally, the reel with the downline flexible pipe and the reel drive system and tensioner were shipped from Aquatic’s yard in Peterhead to Saipem’s Boscongo yard in Pointe-Noire, Republic of the Congo, before deployment to Uruguá field. At Pointe-Noire, the equipment was mobilised onto the Normand Cutter before crossing the Atlantic to commence the pipeline pre‑commissioning.

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A downline flexible pipe destined for the Uruguá~Mexilhão-1 gas flow system situated in the Uruguá oil and gas field, Santos basin, offshore Brazil, will have travelled many thousands of kilometres before it reaches its final destination. It also requires a purpose-built Aquatic reel to operate properly.

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Picturing the solution “The survey was very quick and we could see immediately how everything fitted together. During pre-engineering, when we were trying to devise a solution, it was valuable to have such an accurate visual of the problem.”

That was Acergy project manager Scott Winning talking. The problem he was referring to was cracking in a caisson structure attached to the massive oil storage tank that sits on the seabed beneath DONG Energy’s Siri platform, which is situated in 70 m of water about 240 km off the Danish coast. The survey that provided his engineers with such a good visual was carried out using a remarkable new 3D sonar imaging system supplied by Seatronics.

It was in the middle of last year, during a routine platform inspection, when DONG established that it had a problem with the Siri platform and had to shut down production, not only from Siri but also from the

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The Siri image was captured using the BlueView unit mounted on a Fugro-operated ROV. The unit is in the top right-hand corner of the photograph (left). All the data from the unit was returned to a simple laptop PC, seen here (right) on the lefthand corner of the ROV operators’ desk.

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neighbouring Nini, Cecilie and Stine fields. Following work by DONG engineers to determine the cause of the cracks in the caisson support, Acergy was engaged to devise a solution to the problem, one that would enable production to be restarted as quickly as possible.

Believing that having a good overall picture of the structure and the surrounding area would be important to help his team engineer the best solution to the problem, Winning asked Fugro, which had found the problem in the first place, to carry out a further remotely operated vehicle (ROV) survey. But, with visibility down to 5 m at the seabed, the challenge was how to obtain the topographical data Winning wanted.

Seatronics provided the answer: one of the latest miniature, multibeam sonar systems developed by BlueView Technologies, which is based in Seattle, USA. The sonar system was hand-carried offshore by a single sonar technician, and it then took less than a day to integrate and test the unit with the ROV. The survey to collect data took about 10 hours and involved setting the ROV down on the

seabed at various selected locations. In all, eleven 3D sonar images of the area were taken and combined to provide the final result. Shown top right, the picture, which covers an area roughly 50 × 40 m, may be viewed on a computer screen from any angle, including looking upwards from the seabed right into the problem area.

As Winning said, the results of the BlueView survey were valuable in developing a solution to the problem on Siri, which involved installing a custom-designed support structure for the caisson sitting on two new mud mats strategically placed on the seabed. Acergy completed the remedial work in January this year, and Siri and its linked fields were back in production very soon afterwards.

Alistair Coutts, global business development manager for Seatronics, said, “We expected to get a good result with the unit following a trial we conducted in Aberdeen harbour last year. The quality of the information we obtained in the harbour and in this first commercial application in the North Sea were exactly the same. As word of the technology spreads, we expect to see demand for the equipment grow rapidly. It is the ideal tool for simple yet detailed inspections of smaller, defined areas where there is limited ROV access and poor visibility.”

Seatronics has an exclusive reseller’s agreement with BlueView Technologies under which the two companies work closely together to market BlueView’s miniature, multibeam sonar systems worldwide within the oil and gas industry.

How the Siri DATA was obtained The Siri survey was carried out using a BlueView BV5000 mechanical-scanning, multibeam sonar system. The patented unit comprises a high-frequency (1350 kHz) multibeam sonar head coupled with a very precise pan-and-tilt mechanism. This enables a series of high-resolution 2D profiles to be collected from the same fixed location. A 3D image in the form of a standard point cloud is automatically generated by combining the 2D profile data. This image can be viewed and manipulated in all laser and sonar point-cloud viewing software packages.

The BlueView system is unique in not requiring any other sensors to produce good-quality 3D data.

An image of a more extensive area is easily produced by overlaying the images collected from adjacent locations around a site. Using standard laser scanning software, adjacent scans are snapped together using like features in the models rather than precise location information. This is how the Siri image was built up.

The technology has the advantage of being very directionally sensitive, which reduces multi-path effects and results in unusually clean raw data. In the past, the time needed to clean traditional multibeam data from complex structures could far exceed that necessary for data collection. Normally, a technician can clean and combine BlueView scans at a rate of an hour for each hour of data collected.

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A 3D point-cloud image of the problem area beneath DONG Energy’s Siri platform. The caisson attached to the side of the storage tank can be clearly seen, with conductors emerging beneath it. A feature of the Blueview system that marks it out from other multibeam sonars is its ability to look upwards into the structure.

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The new splash-zone guide has an internal diameter of 30 in., which is sufficient to embrace a 20-in. centralised conductor. Designed to be clamped to two jacket cross members in the splash zone, the guide is relatively lightweight at around 3 t. Keeping the weight down was important, as the project plan required the guide to be fitted by a construction crew abseiling from the platform.

Guiding principles overcoming challenges to ensure the success of an unusual project to add a new well slot to an existing offshore platform.

Claxton was initially subcontracted to design, fabricate and install a new conductor guide and centraliser in the platform’s splash zone. Fitting the new guide, a great team effort with main contractor Production Services Network’s (PSN) construction team, was successful; the guide was lifted over the side of the platform, slung into place within the jacket structure and firmly secured within a few hours by a crew of four abseilers. The picture (left) shows perfectly what was involved.

Thereafter, there were some changes to the original plan. With the field operator’s drilling crew on site and preparing to drill the conductor socket, concerns emerged that whipping of the drillstring at the congested cellar deck level might lead to clashes with surrounding steelwork or piping.

“The general feeling was that the provision of a drill bush in the guide at the splash-zone level would not be adequate to contain the problem and that a temporary guide was required at the cellar deck,” explains Bob Leggett, Claxton’s project manager for the work. “As we were already involved in the project and have a lot of previous experience with this type of work, we were asked to come up with a solution to the problem.”

Claxton’s answer was to install a temporary guide in the opening through the cellar deck and to provide a bush that could be run on the drillstring to sit in the guide. Once landed in the guide, the bush, which had a polymer lining and formed a clearance fit around the drillstring, was locked in place to provide the necessary restraint at the critical point.

With the initial drilling complete, the temporary guide was removed and the conductor was run into the hole.

In another departure from the plan, the drilling crew decided not to install the conductor centraliser within the splash-zone guide. This was because they were concerned about problems with engaging the

centraliser in the guide and the effect this would have on the drilling schedule. A different type of centraliser was therefore called for, one that could be handled and installed by abseilers, like the guide itself.

With the agreement of PSN and the operator, it was decided to construct the centraliser in three segments. This enabled the centraliser to be retrofitted in the guide on completion of the drilling activities. Again, the installation of the guide was a joint effort with the PSN construction team and a complete success.

David Pugh, PSN’s project engineer, says, “Projects involving several responsibility interfaces are prone to unforeseen changes. The project team has to be flexible and able to respond quickly when deviations from the plan occur. Claxton has a lot of experience of drilling-associated work and was able to provide that quick response with an efficient design, build and install service. The Claxton staff were valuable members of the project team and brought with them a positive attitude to problem solving.”

Bob Leggett takes satisfaction from having been part of an imaginative project to prolong the life of an installation that was past its production peak. He says, “Claxton has previously undertaken projects to regain entry to reservoirs via existing well slots, so-called slot recoveries. By adding an entirely new slot, you minimise the effect on production from the existing wells; though, as here, you have more structural issues to deal with. Each approach has its advantages. What is important is that the range of options available to operators seeking to extend the life of existing structures has been extended.”

Claxton was called to this challenging project by PSN, the main contractor responsible for topsides design and construction management. The drilling, conductor and tree design, and the installation were managed by the field operator.

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The addition of a new well slot to a major operator’s gas platform in the UK Irish Sea will significantly extend the production life of the facility. As is often the case offshore, the project was not without its challenges and called for flexibility on the part of all concerned, not least Claxton.

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meeting wind industry needs flange facing gets simpler and faster.

When it comes to portable flange-facing machines, Acteon company Mirage has few serious rivals. Part of the reason for this is the constant striving by the company to respond to the needs of its customers, which, as Mirage managing director Richard Silk explains, centre on speed and simplicity.

“Whether our flange-facing machines are being used in a maintenance or a production setting, there is invariably pressure to get the work done as quickly as possible. On top of that, there is a huge demand for machines that can be easily operated by less highly trained individuals.”

Mirage rents or sells a variety of flange-facing machines capable of dealing with flanges from just a few centimetres wide to those up to 8 m in diameter. A common feature is the ease with which they can be set up. The machines are generally designed with independent bases that have axially adjustable feet. This enables the machines to be positioned against the flange to be faced within 0.25–0.5 mm very quickly and without too much skill.

Another common feature of the machines is the gearbox, which is preset to produce a variety of common surface finishes; this too saves time when preparing a machine for use.

For users that are happy simply to produce a flat finish on the flange (with no defined machine profile), machines can be supplied with milling heads rather than single-point cutters. These reduce the actual machining time dramatically and have found great favour in the rapidly expanding wind turbine manufacturing sector.

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“The makers of wind turbines are under immense pressure to increase productivity,” says Silk. “Their order books are filling

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rapidly as more and more wind farm developments get the go-ahead in many countries around the world. Flange facing is a significant part of the manufacturing process: the composite blades are each finished with a part-steel flange to connect them to the turbine generator, which itself sits on a steel flange on top of the tower.

Getting the tower flange very flat is particularly important, as this has been found to heavily influence the life of the bearings in the turbine. Here, we are seeking to achieve 0.1-mm flatness around a flange that can easily be 2–3 m in diameter.”

Silk points out that the size of modern wind turbines makes it impractical to take the blades or the towers to a fixed flange-facing machine and that a portable machine is the only option for preparing the flanges. Since 2000, Vestas, probably the world’s best-known wind turbine supplier, has faced roughly 10,500 blades using one of six Mirage machines that they own. During that period, the machines have proved to be reliable and their maintenance requirements have been minimal.

More importantly, over that period, the flange-facing process has been speeded up considerably. Initially, the company was facing two blades a day. It is now treating one blade every 30 minutes. Setting up the machines is much simpler than it used to be, and the milling head reduces the cutting time compared with a single-point cutter by roughly 80%.

“Wind turbine manufacturing is a fascinating business,” says Silk.

“It has moved forward very quickly over the last few years and has stimulated a great deal of development on our side. The flange-facing machines that we are supplying now are very much more advanced than those of a few years ago. I feel that we can be proud of the contribution we are making to this important, emerging industry.”

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“The flange-facing machines that we are supplying now are very much more advanced than those of a few years ago.�

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Suction piles for thunder hawk

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cost and reliability issues Trigger intermoor innovation.

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The Thunder Hawk piles were designed to be launched without the need for an A-frame. Although the Joshua Chouest came fitted with one, it was not used on this occasion.

Suction piles have come to form one of the mainstays of the industry as vital components of deepwater developments on generally softer ocean floors. They are easy to install, as there is no driving involved; they withstand extreme lateral and axial loads; and they are reusable.

That is not to say that the technology cannot be improved, as a recent InterMoor project for Murphy Oil in the Gulf of Mexico demonstrates.

Murphy asked InterMoor to supply and install suction piles to anchor two pipeline end terminals (PLET) as part of the Thunder Hawk field development in 1800 m of water in the Mississippi Canyon Block 734.

Given the seabed conditions and knowing that each pile needed to withstand a lateral load of about 250 t, InterMoor engineers determined that 5-m-diameter, 29-m-long piles would be required: medium-sized by general standards, but larger than normal for PLET piles.

The piles, each weighing 159 t, were fabricated at InterMoor’s facility in Amelia, USA, and were equipped with “devil’s-claw” ratchet mechanisms to tension the chain linking each pile to its PLET: 15 m across the seabed in one case and 52 m in the other.

Although this was reasonably standard, the piles incorporated two significant improvements over previous industry designs. The first relates to the vent valves on the top of the piles. These need to be open when the pile is being lowered through the sea and when it selfpenetrates the seabed, and then closed before suction is applied to the pile to pull it completely down.

“Butterfly valves have traditionally been used to vent the piles,” explains InterMoor project manager Tom Bauer. “But being based on bronze castings and normally around 40 in. in diameter, they are not cheap. Further, as most are supplied from the Far East, they require extended lead times. Unfortunately, we have also experienced problems with them not sealing perfectly in deeper waters.”

With cost, schedule and reliability particularly high on Murphy’s agenda, Bauer’s team decided the time had come to develop an alternative. With valuable input from Houston-based valve specialist Premium Solutions, InterMoor devised a vent cap system with O-ring seals. Easy to fabricate, relatively inexpensive and simple to operate using a remotely operated vehicle, the valves worked perfectly on the two Thunder Hawk piles.

“Since this job, the design has really taken off,” says Bauer. “We have used similar valves on the followers that we use to install our patented suction-embedded plate anchors (SEPLA), and we have also supplied Cameron with 28 of the valves for manifold foundation piles for BP’s Plutão, Saturno, Vênus and Marte development, offshore Angola.”

The second innovation involved very simple additions to the piles. Pad eyes were placed roughly one-third of the way down the piles’ length so

they could be rigged using so-called high hip slings (1.5–3 m above the centre of gravity). This made it possible to launch the piles over the back of the Joshua Chouest anchor-handling vessel without using an A-frame.

The use of the high hip slings gave the offshore team complete control of the pile as it passed over the vessel’s roller and during the crucial short period when it rotated from horizontal to vertical. The hip slings take the weight of the pile until it gets underneath the vessel roller, when the normal top slings take over.

“We have previously almost always used a boat fitted with an A-frame to get these piles into the sea safely,” says Bauer. “Rigging them with high hip slings means we can use a wider selection of vessels, which potentially results in cost and schedule advantages for our customers.”

InterMoor intends to use the technique again and to adapt it so that it can also install SEPLAs from less-sophisticated vessels. The high hip slings will be particularly valuable here as, in their absence, it is virtually impossible to retrieve the followers over the vessel roller without an A-frame.

Bauer notes that the whole Thunder Hawk operation turned out flawlessly, aided by some dead calm seas. The launch and installation of the two piles could not have been easier. “We were fortunate with the weather on this occasion,” says Bauer, “But we are confident from what we have learned this time that we will be able to repeat this kind of exercise without an A-frame under more-demanding conditions in the future.”

For Murphy, the PLET suction piles formed a small, but vital, part of a much bigger venture; any problems or delays with the piles would have had a serious knock-on effect on the whole Thunder Hawk development schedule.

“The main reason for choosing InterMoor for this part of the development was to minimise risk,” says Luc Chabot, special adviser, Murphy Oil. “The company is well known for its knowledge and understanding of suction piles. Also important to us was InterMoor’s ability to provide a highquality, end-to-end service covering design, fabrication and installation of the piles. We trusted them to understand our requirements, provide a realistic and cost-effective solution, and then implement it with the minimum of hassle.”

Chabot explains that analysis had shown that repeated heating and cooling of the flowlines was likely to lead to an unusual effect, sometimes called pipeline walking, where the pipe gradually edges its way along the seabed. In view of this, it was important to install the piles correctly and exactly in the right spot, within 0.3 m in the direction perpendicular to the projected pipeline axis, to ensure that the maximum load capacity was achieved and without applying any twisting forces to the PLETs. “That InterMoor succeeded in doing this, even though work was hindered by the close presence of our drilling rig, the departure of which was delayed, is testament to the technical and management ability of the people they had on the project,” says Chabot.

As said at the start, suction pile projects like this are never going to make the main story. Nevertheless, there is much quiet satisfaction at InterMoor about the way the work went and the contribution the company made to this important development for Murphy Oil.

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When the history of the offshore oil industry is finally written, the chances are that not too many pages will be devoted to suction piles. This is perhaps understandable in the light of the many exciting technology developments that the industry has spawned. Nevertheless, their importance should not be underestimated.

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Acteon offers an outstanding portfolio of interlocking products and services targeting the subsea arena. We can align our knowledge, skills and experience in a variety of ways to provide inventive solutions to the complex challenges faced by subsea developers and operators.

For more information about how Acteon companies can help you, visit

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