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As concerns over oil resources grow, many countries and companies are searching for petroleum deposits on the depths of the ocean floor. Large offshore oil rigs are being constructed to search for oil. Many of these are starting to use composite solutions for the pipes and tubes that rigs use to exploit and produce petroleum.
(Published on April 2006 – JEC Magazine #24)
For the past seven years, Spencer Composites has been involved in numerous ventures with oil companies hoping to drill for petroleum underwater. Companies traditionally use steel pipes for the extraction and distribution, but Spencer has been providing them with pipes made out of carbon-fibre composites and trying to convince oil firms of the advantages of using them over steel.
It hasn’t been an easy sell so far, for reasons relating both to logistics and to safety, but Dr Brian Spencer, founder and head of Spencer Composites, is convinced that eventually the oil companies will recognise that composites are far more cost effective and just as safe as steel.
Carbon fibre deemed most effective
The projects that Spencer Composites has worked on for various oil companies usually use carbon-fibre composites for their high strength and modulus compared to their density. They will use fibreglass occasionally: for example, if they need to provide some corrosion protection between metal pieces, or if the client needs something that does not conduct electricity.
Spencer Composites uses a filamentwinding process to produce the composites. Dr Spencer said that most are done with fairly standard epoxies, although occasionally they will use specialised resins for higher temperatures. He added that they normally use standard-modulus carbon fibre, but sometimes higher modulus material; essentially, though, it is all 34-million-modulus carbon fibre.
“Normally, these tubulars we use have a thin metallic liner on the outside to provide a wear or gouging surface, in case they put tools down that want to “grab” the wall. But even in metal tubes there is a wear tolerance, because tools go down and can wear against the sides, so they do allow a certain wear. We provide that wear with a metal tube, but the metal tube doesn’t need to have the high strength properties they need to use in all steel-type solutions.”
Challenges to be overcome
The use of composites on offshore oil rigs is not yet commonplace, as a number of obstacles remain. The first problem concerns the supply of carbon fibre. Only about 16,000 tons of carbon fibre are produced each year, whereas the same amount of steel is made nearly every day.
“There are concerns about a shortage of supply, which would mean you go through all this design and development, and then all of a sudden they can’t get the material. The other possibility is that the price becomes unstable because demand is more than the supply. However, the price of steel is going up, so there is a growing concern about the supply and cost of steel – which could result in people looking at alternatives such as composites.”
Based in Sacramento, California, Spencer Composites Corporation is dedicated to the research, design, development and manufacturing of filament-wound composite products. Its facility has over 4,600 square metres of space available to fabricate products up to 6m in diameter and 27m long. The company fabricates composite products and components using thermoset and thermoplastic processes, has expertise in thick-wall composite processing, and is experienced in the processes of filament winding, pultrusion, RTM, VARTM, press moulding and hand lay-up.
There is also much concern over the safety of using composites. Dr Spencer said he understands the reluctance of company executives who, with only a few years to go before retirement, are reluctant to run the risk of something failing just before they leave. Steel may be more expensive, but people are more likely to use it – because they are familiar with it, and know it works.
“These guys are very conservative, and nobody wants to have another Exxon Valdez occur, or another drop of oil to go into the ocean, for that matter. A few people see the potential long-term advantages of composites and have been able to convince the higher ranks in their companies to proceed ahead. Lately, there have been some papers written by the oil companies looking into the economic advantages of composites and, in my mind, there is no question that the use of composites is going to grow.”