Hot tap record on Åsgard


A


n underwater welding robot and remote-controlled machines have in-


stalled a new tie-in point on a live gas pipeline for the first time.


The hot tap installation is the first to be carried out in connection with preparations for Statoil’s Åsgard subsea gas compression project in the Norwegian Sea, and thus also represents a milestone for the project.


The tie-in point was


welded on to the Åsgard B pro- duction flowline at a water depth of 265m. After 10 days on the field, the hot tap operation team on board the Technip-owned vessel Scandi Arctic confirmed the suc- cess of the pioneering operation. “For a subsea engineer, this can be compared with landing on Mars,” says Kjell Edvard Apeland, project manager of the remote-controlled hot tap development in Statoil and head of the operation on the Åsgard field. 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 ef- fect on pressure and produc- tion.


“When the compressor module and the manifold for Åsgard subsea compression are installed next year, we will


Åsgard compressor


connect the pipeline from these to the hot tap tie-in point,” says Apeland.


The Åsgard subsea com-


pression project will be realised in 2015, as the first of its kind in the world. Compressors will be in- stalled on the seabed, instead of on a platform. This will im- prove recovery from the Mikkel and Midgard reservoirs by around 280 million barrels of oil equivalent.


Statoil said: “Hot tap tech- nology is a technological break- through, 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, with- out stopping production, yields considerable flexibility and sig- nificant savings. “Since we will be connect-


ing 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 dis- rupting production,” says Torstein Vinterstø, portfolio manager for subsea compres- sion projects in Statoil. “The savings are measured


Offshore Technology November/December 2012


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 10 days we spent now - possibly as long as three months,” he says.


Home-grown technology The method was developed by Statoil, and the company says there is no comparable tech- nology.


The work to develop the technology started in 1999, and was developed in Statoil’s pipe technology environment at Killingøy outside Hauge- sund. Statoil’s expertise in tie- in and repair of pipelines is gathered there. Statoil has already thor- oughly tested the hot tap tech- nology, with good results. Remote-controlled hot tap


has previously been performed on Tampen Link on the Stat- fjord 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.


25


Subsea compression


“For a subsea engineer, this can be compared with landing on Mars”

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