Lifting & handling - No pipe dream06 June 2005
Oil and gas pipelines could be built at up to five times the rate they are at present. This could be achieved with trains of tracked vehicles up to half a kilometre long, supported in remote and inaccessible areas by airships with lifting capacities of up to 300 tonnes.
A fraction of the number of people would need to be accommodated on site and construction costs could be cut by up to 30%. While the development effort is global, the lead and much of the cleverest parts of the technology are British - and on a scale that Brunel would have been proud of if he could have been around to take part in it.
One organisation leading the charge to bring the pipe dream to fruition is BP. The company's Graham Freeth tells Plant Engineer that "BP depends on technology to give it its competitive advantage." Freeth is heading up the Onshore Pipeline Technology R&D project, taking over work originally begun by Dr Norman Sanderson in 1998. Among other things, Freeth is tasked with finding ways to reduce the development capital cost of building new pipelines by up to 25%. At the same time, BP is working closely with the pipeline contracting industry through IPLOCA, the International PIpeline and Offshore Contractors Association.
In the past, oil and gas were usually produced either near point of use or where they could be easily loaded into tankers, but with increased development in locations such as Alaska, Northern Canada, Siberia and China, this is no longer the case.
Various alternatives have been looked at and costed, including the possibility of burning gas to turn it into electricity and transmitting it over the necessary distances - termed 'gas by wire' - but pipelines are still the favoured solution. They are, however, extremely expensive and time consuming to construct on land, with total projected costs for planned new pipelines coming to more than $50bn, even as much as $120bn in some instances. The typical rate of construction is between 800m and 1.2km per day, a rate which has little changed over the last 30 years. This is compared with typical offshore construction rates of 7km per day. The construction of a new pipeline typically takes two to three years.
What's more, wherever there are large numbers of workers on a construction site, there will, despite best efforts, inevitably be accidents. Traffic accidents are a particular problem, as are incidents involving people and equipment. The more people there are on a site, the larger the potential number of accidents,with all the associated costs and problems.
The cost breakdown of building a land-based pipeline based on present day technology is: camp 35%, logistics 24%, excavating the trench 11%, mechanical operations 15%, burying the pipe 6%, clear right of way, including space for temporary access road 8% and everything else 1%.
There have been very few significant advances in the construction of pipelines on land, but two such advances were the replacement of cableoperated excavators by hydraulic machines in the 1960s, and the development of automatic and semi automatic welding.
One trend aimed at reducing costs is to turn to new, higher strength steels such as X70, and more recently X80, with UTS values of 70,000 and 80,000 psi respectively, capable of transporting oil or gas at up to 90bar pressure. The oil companies are now looking at the possibility of using X100, which can transport oil and gas at up to 170bar, and X120, which can withstand even higher pressures. Much money has also been spent on improving welding procedures, working with the Welding Engineering Research Centre at Cranfield University. This has led to the development of an automated pipe welding machine, with dual tandem heads and eight feed wires.
While these developments are important, BP feels more radical improvement is needed to improve the basic construction method. At the present time, this consists of loading 12m-long sections of pipe on trucks and laying them, end to end, alongside a trench. They are then welded, requiring seven or eight passes, and coated. After this, bulldozers equipped with side booms very carefully lift the pipe and lower it into the trench, which is then back filled. Side boom bulldozers cost up to $650,000 each and are primarily designed to push rather than lift. There are about 20 lifting operations which individual pipe sections go through between manufacture and placement into the ground.
Where tie-ins are needed - where sections of pipeline have to be joined because of river crossings or breaks in the project - the process is even more lengthy and complex.
The ends of the pipe overlap and one is cut back so that the two can be joined. However, by the time the pipes are ready to be joined, thermal expansion or contraction has often occurred, meaning that they are either too long or too short. This leads to considerable clamping, pulling, pushing and manoeuvring - a drawn out process which means that just three tie-ins can usually be accomplished in a day. The crew of men required is normally 35, and on average, there is a tie-in about every 600m of pipeline.
Concern about these processes prompted a workshop in Windsor in June 2004, staged by BP and IPLOCA. Participants included 60 representatives of contracting companies from each of the world's continents, and representatives of some of the larger companies building mobile construction plant, such as Caterpillar and Komatsu, as well as representatives from Shell and Agip. The participants were divided into six working groups, each tasked with devising three to five good ideas, then presenting them to the plenary session to be voted on.
The five lead ideas, in order of popularity, were:
1) To lay pipelines using an automated method based on the technologies used in offshore pipelaying barges
2) To use longer pipe lengths
3) To use sky hooks in the form of lifting airships
4) To improve the construction and mobility of prefabricated camps
5) To develop an automated tie-in machine.
It was apparent that a land-laying barge, similar to an offshore pipe-laying barge, would be too inflexible to cope with variations in terrain, so it would have to take the form of a train of vehicles. These could start with a skid for pipe preparation, followed by welding, non-destructive testing, coating, and finally one or possibly two machines to excavate the trench, place the emerging continuous pipe in it and back fill. In rocky terrain, the trench might have to be dug ahead of the train, which would be supported on tracks running on each side.
Studies are being conducted by German companies Innologics and ILF, working in conjunction with Bechtel. Among other advantages, such a scheme would mean disrupting the landscape in a strip only 20m wide, instead of 37m wide as is currently the case. Approximately 75 workers would be required, with 400 to 500 support staff, as opposed to 220 people at present, with as many as 2,500 people in supporting camps. This could mean elimination of the large semi-permanent encampments; they could be replaced with much smaller, more mobile encampments (based on Winnebagos) which could be driven away when they had served their purpose in a particular location. Again, the environmental impact would be vastly reduced.
The idea of using longer pipe lengths seems to be a non starter, but the use of lifting airships is a possibility - particularly in remote areas where there are no roads, or in very mountainous or boggy terrain. If you are envisaging 21st-century versions of the Hindenberg airship and its fiery demise, think again. The airships contemplated here are entirely different. In their simplest form, they could be lifting gas bags, as is already the case in one region of the US for lifting tree logs on steeply sloping hillsides. For oil pipes, they could be attached to bulldozers, with the actual lifting undertaken through cables attached to winches on the bulldozers.
At their largest, which would eradicate with the need to construct access roads for trucks, they could be huge airships filled with inert helium capable of lifting and transporting up to 300 tonnes at a time. Using lifting helicopters is not an option - they have very poor fuel efficiency, are expensive to run and have a limited lift capacity.
Big airships, however, pose many challenges. For example, once the cargo has been offloaded, how can enough ballast be reloaded quickly for the return trip? As an alternative to water ballast, how could enough sand be loaded quickly in desert terrain, or ice in Siberia? What happens when the temperature changes suddenly, and with it the airship buoyancy? And how about the problems of manoeuvring a large object in a high wind for unloading and loading? The original airships were manhandled by large numbers of men - not a viable alternative in today's world.
The idea that has seen the most rapid progress, however, is the automatic tie-in machine, thanks to the ingenuity of Bennett Associates in Rotherham, best know for its design of the Falkirk Wheel canal lift in Scotland and the Airbus A380 wing skin creep forming facility.
The proposed tie-in machine will allow the pipe ends to be placed in a frame with a gap between them. Into the gap a short length called a 'pup' will be loaded, with clamps already attached to it. The clamps will be equipped with hydraulic that could squeeze out any ovality, or push/pull the pipes away or towards each other. The ends will then be faced off and automatically welded.
In all cases, as Freeth points out, BP is not a construction company. "And we are working with construction companies through IPLOCA to bring this project to realisation. Oil companies may have to expect to invest seed capital but we would expect the bulk of the development costs to be funded by venture capital investment. A joint industry project (JIP) is planned to start next year and interested parties will be welcome to join before this date."
Feasibility studies should be completed by the end of 2005, with a view to moving to a JIP in 2006. The new technologies are expected to be developed and in use within seven to ten years. The automated tie-ins will come first, followed by the land trains, followed by the airships.
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