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New Challenges in the North Sea

"The North Sea oil and gas industry is increasingly confronted with ageing platforms and exhausted reservoirs. In this area, there are a relatively large number of platforms and drilling locations that will soon be reaching the end of their service life or are already at this stage," says Tobias Löprich, responsible for technical documentation and risk assessments at MAX STREICHER GmbH. Therefore many drill holes need to be decommissioned and sealed in accordance with the local statutory provisions – also referred to as 'plug and abandonment'.

The problem is that the jack-up rigs used in the North Sea rarely feature the equipment that would enable the drill holes to be decommissioned in an economic or technically correct manner. Tobias Löprich explains: "This may be down to gas or oil installations being positioned incorrectly on the sea bed, meaning that it is impossible to make any progress using the standard jack-up platforms."


A Solution with a Future

There are two potential solutions to this current problem. On the one hand, you can upgrade the ageing platform, but this option is extremely expensive due to the very high offshore labour costs. In addition, the technical implementation often requires considerably more effort than on land due to the offshore situation and weather conditions.

MAX STREICHER GmbH & Co. KG have introduced the alternative in the form of their VDD 400.2 deep drilling rig. The concept involves positioning the VDD 400.2 on the old platform as a piggy-back. The VDD 400.2 must therefore be suitable for use on a whole range of offshore platforms. Once the work is done – that is, once the 'plug and abandonment' process is complete – the VDD 400.2 can be relocated to the next platform. Moreover, the VDD 400.2 can also be used for new drilling locations.

The Norwegian company ARCHER commissioned STREICHER to develop and construct one such modular offshore drilling rig. In the process, the VDD 400.2 was designed, built and accepted in accordance with the Norwegian safety standards (NORSOK), which are the strictest in the world. Following completion, certification and admission into operation, the platform will be dismantled down to the individual modules and then reassembled on site in Norway. The VDD 400.2 will then enter service on the Heimdal gas platform of the Norwegian energy company STATOIL.

The VDD 400.2 modular offshore drilling rig from MAX STREICHER GmbH consists of over 100 individual modules, has an unladen weight of around 1,300 tons and operates with a drill string weighing a maximum of 400 tons. The maximum depth, which is the correct mining term for referring to the length of the drilling hole, comes to around 7,000 metres. On the VDD 400.2, the handling of the thread strings – which can be up to 14 metres in length – is partly automated by means of a pipe handler. This enables the installation and removal of thread strings, pipes and other drilling equipment to be controlled at the push of a button. Unlike classic drilling rigs, therefore, the thread string is no longer manually tightened and raised on a winch by drilling workers.

The Heimdal Platform

The gas production in the Heimdal gas field has fallen considerably in recent years. Today, the Heimdal platform primarily acts as a central junction in the North Sea for processing and distributing gas. Supply originates from the Huldra, Oseberg, Skirne and Vale fields and is routed to the Norwegian mainland via the Vesterled Statpipe. At peak levels of extraction, the Heimdal platform is responsible for around 15-20% of all Norwegian gas production.

Assembly and Disassembly

"This idea of ensuring suitability for use on as many platforms as possible makes it essential to come up with a physical concept for the drilling rig, ensuring that the module set-up can be adjusted in as small an area as possible. The rig must also be able to accommodate all the necessary equipment," notes Erwin Nutz, responsible for the project at the STREICHER Group. He adds: "You can picture it as follows: all modules are tightly stored and stacked in order to take up as little floor space as possible." The complete floor plan of the VDD 400.2 rig therefore comes to 14 metres by 12 metres, not including energy generation. The VDD 400.2 can be adjusted along its lateral axis and its longitudinal axis in order for an entire grid of drill holes with varying drill depths to be run-in on the gas field.

Hawke Connectors making it all possible

The modular concept of the VDD 400.2 wouldn't be possible without Hawke's connectors. The process of disconnection, removal and reassembly in another location is completed with ease in a few simple steps. Robert Paternoster, who is responsible for electrical equipment at the STREICHER Group, explains: "Of course, we could also clamp all the cables in place, but this would generate two separate issues. As well as increasing the number of potential sources for a fault, it also leads to increased offshore wage costs."

When removing the Hawke connectors, you only need to ensure that the cover is screwed back on. A warning to this effect is therefore attached to all Hawke connectors, and each cover is secured to the connector by means of a chain. All Hawke connectors are also colour-coded, preventing any errors from slipping through the net in the course of attachment and removal.

Hawke connectors from the InstrumEx and ControlEx ranges are used in the STREICHER drilling rig for the purpose of connecting small and medium-sized cables. These connectors are ideally suited for use on the platform and in tough environments. The InstrumEx range is certified for Exde and the ControlEx Exd types of protection as well as being extremely robust, maintenance-free and suitable for application temperatures from -40°C to +60°C. Hawke connectors also feature all necessary approvals for the Ex field in accordance with ATEX, IECEX and GOST-R.

Alongside the connectors, large quantities of HAWKE cable glands are used in terminal boxes and cable inlets on the platform. The cable glands from Hawke – which are Exd & Exe certified are practically the standard product in the Ex field.

MEET THE EDITOR

Steffen Hammon

Hubbell Product Manager for JACOB GmbH – Hubbell Distributor

Steffen has been working with Hawke distributor, Jacob GmBH, for more than 17 years now. In 2011 he took over the responsibility as a Product Manager for the Hubbell products at Jacob. As a hobby Steffen loves to follow his favourite football club Bayern Munich and to watch their matches in stadiums around the globe

 

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