BP Schiehallion replacement plan may pose threat to tanker traffic at Sullom Voe

BP is planning to remove water from its Schiehallion oil offshore from 2015 which could spell the end for around one-third of the tanker traffic through Sullom Voe.

In the QUAD4 Project the oil company intends removing its troubled oil storage ship in 2014 to be replaced by a bigger better version which could stay west of Shetland for 30 years. Crucially, it will be designed to separate and clean the water before re-injecting it down the wells.

The oilfield has been plagued with problems which have seen it out of production for large chunks of time, including most of this year and effectively five months of last year. But it is seen as still having great potential and BP intends almost doubling the number of wells in the field, the associated Loyal field and other nearby discoveries.

When the field is operating the oil comes to Sullom Voe by shuttle tank­er Loch Rannoch to settle and have the high water content re­moved. If that can be done offshore it might lead to direct exports from offshore, spelling the end for Schiehallion trade, which earns millions for the council each year as harbour authority.

BP’s scoping report for the pro­ject’s environmental impact assess­ment states that “oil from Schiehal­lion/Loyal will be stabilised and off­loaded to shuttle tankers for export” while “excess gas will be exported via the existing gas export pipeline to Sullom Voe Terminal as per current operation”.

This seems to hint at a similar operation to that which is done from the nearby Foinaven field these days with tankers taking the oil direct to market instead of Flotta in Orkney, as used to happen.

Even if the oil does continue to stop off in Sullom the council faces losing more than a year of income from the time production stops around mid-2014 until the new FPSO comes on stream in late 2015.

BP states: “In recent years oper­ating challenges on the FPSO have resulted in a deterioration of the production operating efficiency and the existing vessel is unable to fulfil the processing requirements of the anticipated economic field life. Re­development of the surface pro­duction facilities, new wells and an expansion of subsea infrastructure is therefore required to access the remaining hydrocarbon resources.”

The existing 246-metre FPSO was the biggest of its type in the world when it was built in 1997. The new one will be 270 metres long with an oil storage capacity of one million barrels. It will do less flaring of gas offshore.

It will have to handle the large amount of water that comes up with the oil, which has been a feature of the field and will get worse as production con­tinues and the fields’ life is extended longer than pre­viously expected. It will be cleaned and sent back down the wells.

BP had considered making do with the existing ship, taking it ashore for modifications, sending the oil to a new platform closer inshore or building a new fixed oil rig or semi-submersible platform.

There are currently 53 wells for extracting oil and gas and re-injecting water and BP expects a further 50 will require to be drilled with the first half being done over the next 10 years.

BP expects to sanction the plan early next year.