For the very first time, remote-controlled machines and an underwater welding robot have installed a new tie-in point on a live gas pipeline, without the pipeline being prepared in advance.
Subsea Hot Tap Video Link
These types of operations can save Statoil lots of money in the long run.
The hot tap installation is the first to be carried out in connection with preparations for Åsgard subsea gas compression in the Norwegian Sea, and thus also represents a milestone for the project. The tie-in point was welded on to the Åsgard B production flowline at a water depth of 265 metres.
After ten days on the field, the hot-tap operation team on board the Technip-owned vessel Scandi Arctic could confirm success in the pioneering operation.
Kjell Edvard Apeland, project manager of the remote-controlled hot tap development in Statoil and head of the operation on the Åsgard field. (Photo: Rune Solheim)
“For a subsea engineer, this can be compared with landing on Mars,” says Kjell Edvard Apeland. He is project manager of the remote-controlled hot tap development in Statoil and head of the operation on the Åsgard field.
Simply explained, a remote-controlled hot tap operation consists of a robot welding a T-piece on to the pipe, while gas is flowing through it. When that has been done, a remote-controlled drilling machine will drill holes in the producing pipeline, with no effect on pressure and production.
“When the compressor module and the manifold for Åsgard subsea compression are installed next year, we will connect the pipeline from these to the hot-tap tie-in point,” says Apeland.
The Åsgard subsea compression project will be realised in 2015, as the first of its kind in the world. Compressors will be installed on the seabed, instead of on a platform. This will improve recovery from the Mikkel and Midgard reservoirs by around 280 million barrels of oil equivalents.
Hot tap technology is a technological breakthrough, and a door opener for developing marginal fields, as well as extending the lifetime of other fields.
The ability to connect anywhere on a pipeline, without stopping production, yields considerable flexibility and significant savings.
Torstein Vinterstø, portfolio manager for subsea compression projects in Statoil. (Photo: Anette Westgård)
“Since we will be connecting a new compressor station on the seabed to an existing pipeline system on Åsgard, it is very beneficial to use the hot tap technology to avoid disrupting production,” says Torstein Vinterstø, portfolio manager for subsea compression projects in Statoil.
“The savings are measured compared with what it would have cost to perform a similar operation, including shutting down production in the pipeline we were working on. This would also have taken much longer than the ten days we spent now – possibly as long as three months,” he says.
The method was developed by Statoil, and there is no comparable technology.
The work to develop the technology started in 1999, and was developed in Statoil’s pipe technology environment at Killingøy outside Haugesund. Statoil’s expertise in tie-in and repair of pipelines is gathered there.
Open and constructive cooperation with our key suppliers has been instrumental in achieving this.
Statoil has already thoroughly tested the hot tap technology, with good results. Remote-controlled hot tap has previously been performed on Tampen Link on the Statfjord field in the North Sea and on the Ormen Lange field in the Norwegian Sea, but then the T-piece had already been installed on the gas pipeline in advance.
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Statoil has chosen to take out an additional two-year option on the existing contract for diving services with Technip Norge AS. According to a cooperation agreement, ExxonMobil and Gassco could also be potential users of this contract.
PSA Norway has given the companies has given a consent for manned underwater operations down to water depths of 180 meters. The consent and comprises defined and undefined operational and project tasks, as well as repair standby.
The defined tasks are work which Statoil will perform on Glitne oil field during the spring of 2012. It relates to connection of underwater wells to the FPSO Petrojarl 1. The water depth at the site is 110 metres, and the work is assumed to last for five days.
Glitne oil field was brought on stream in 2001 and has been developed with sub-sea completed wells tied back to the leased FPSO facility Petrojarl 1. Oil is transported to shore by offshore tanker loading. Production was originally expected to last for around three years, but a combination of better than expected performance and in-fill drilling has resulted in extended field life.
No need for separate schedule
Gassco has not identified any need for separate scheduled manned underwater operations relating to this consent, but may require repair work on pipelines that the company owns.
The consent also applies to undefined operational and project assignments which may be required during the period for the companies’ production licenses, as well as pipeline systems. This also includes pipelines on a foreign shelf covered by Norwegian jurisdiction.
The consent also includes any surface-supplied diving operations which may be required during the period.
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