New life for North Sea platform

Last edited: 5 February 2015

What do you remember of 1996? It was the year Dolly the sheep became the first mammal to be successfully cloned, the US city of Atlanta hosted the summer Olympic Games, and an online shopping and auction site called eBay was launched

At its peak that year, the crude oil price hit just over $21 per barrel. In the Central North Sea, BP brought a new field online, producing oil and gas via a single fixed platform with accommodation for up to 80 people. Discovered back in 1974, commercial innovations had finally allowed the Andrew field to be developed into a viable operation.

And so the platform was designed - and constructed - to serve a sole purpose: to produce around 80,000 barrels a day at most from a field with a suggested life expectancy of 18 years. Beyond that, there was no reason to consider any further requirements. Andrew was a platform of its time: weight and cost were key limiting factors under the financial constraints of the mid-1990s.

New field, new production

Fast forward to 2015 and this platform is transformed. Thanks to a major project sanctioned in 2011, it has undergone a significant overhaul, with the addition of new processing facilities and a top-to-bottom maintenance programme. The nearby Kinnoull field, discovered in 2008, has been tied back to Andrew and production began in December 2014.

Known as the Andrew Area Development (AAD), the project represents a rejuvenation for this part of the UK North Sea and will allow production to continue from the platform for another decade. “This has been a big project for us and the development is set to add another third to our production in the region,” says Trevor Garlick, BP regional president for North Sea.

Offshore

Much of the AAD is invisible to those flying out by helicopter to the field location about 140 miles (230 kilometres) northeast of Aberdeen, because extensive new facilities lie on the seabed. Beneath the waves, the world’s longest bundle pipeline system has been installed from the Kinnoull wellhead to the Andrew platform.
A pipeline bundle neatly incorporates all the structures, valve work, pipelines and control systems necessary to operate a field, in one large pipe assembly. The Andrew bundle is so lengthy that it needed to be manufactured in four individual sections by Subsea 7, the company that won the £125 million contract to engineer, fabricate and install the system.

The platform

Additional facilities were needed to tie Kinnoull back to the Andrew platform, in anticipation of processing the new field’s hydrocarbons, before delivering them onshore. It was known from an early stage that the jacket - the four legs on which the platform stands - was capable of carrying extra weight, but the engineering effort concentrated on the topsides, where a new 700-tonne processing module would need to be ‘hooked on’.
The platform also underwent a facelift, with extensive maintenance completed before it was commissioned for production once again.

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