Statoil Oseberg B

Scope

The changing of 12 power transformers, which were the main transformers for supplying the rig with electricity.

The job had to be conducted without the risk of the habitats losing power, which was a big challenge due to the power on the rig going offline for up to 30 minutes at a time during the change of the individual power transformers.

The habitats also had to be of a very large size and constructed in such a way that getting the large power transformers in and out of the habitat could be performed without any interruption or incidents.

Due to the main electricity room on the rig where the power transformers were situated not being an EX-zone, and therefore having to be secured at all times, there was also a need for a huge airlock where the power transformers could be stored before either getting removed from or put into the electricity room.

Solution

StS planned and constructed an 850 m³ habitat with an additional 50 m³ airlock. We had to construct it in this size because of the size of the equipment and the rigging setup.

To supply air, we connected three of our market-leading, high-capacity fans in series against one system, all being controlled centrally from our multi-panel. This made sure that the person operating the habitat had full control of all fans, detectors and the atmosphere of the habitat.

To circumvent the issue of power loss, which would lead to the habitat system and habitat fans shutting down and jeopardizing the platform, we constructed a custom UPS battery package which was tested and approved for powering the entire habitat setup for 30 minutes minimum.

Result

A job which at first was deemed impossible to perform due to the challenges with the power supply and the risk for the habitat not being operational during the power outages, was performed on schedule, without any incidents and with extremely positive feedback from the end user, Statoil.

Project planning, innovative technical solutions and the capacity of the equipment was especially highlighted by the client. Our habitat technicians who built and operated the equipment, and also assisted in the rigging of the power transformers, also got very favorable feedback from the client.