The importance of this project cannot be underestimated; major oil companies are developing an ever-increasing number of offshore oilfields in their quest to maintain stable world oil and gas supplies. With the increasing price of oil, deepwater offshore oil fields are now an economically viable oil supply option. This includes European deepwater fields to the north west of Scotland and Norway. Water depth, ocean currents and harsh weather may mean that the deployment of traditional fixed oil production platforms is not technically feasible. However, Floating Production Storage and Offloading (FPSO) vessels are able to work year round, on station producing from deep water oil fields. Flexible pipes, called flexible risers are used to carry oil and gas from sub sea oil wells to the FPSOs. When in service the flexible risers are expected to operate for the life of the oil field that may be up to 30 years.
Approximately 2.5 billion tonnes of oil are processed in the world each year. Of that about 30,000 tonnes is leaked or spilled into the world’s oceans annually. The catastrophic failure of a sub sea flexible riser or flow-line could have immense environmental and economic consequence and is presently considered by the oil majors to be an, 'un-thinkable' accident.
Sub-sea radiography has been recognised by many of the Floating Production Storage and Offloading (FPSO) operators as the only inspection method that can provide the type of information required to detect the defects of concern to major oil companies operating FPSOs. Prior to the developments in the FlexiRiserTest project, only film and phosphor plates (used in CR) have been reported and used in underwater radiography. The main disadvantage of using film and plates, and a reason they are not in widespread use, is that after exposure to radiation it is then necessary for them to be returned topside to be developed and processed – a task that would normally be extremely time consuming and costly when operating in a subsea environment.