SHELL EP Ireland plans to drill a satellite well north of the Corrib gas field which could produce additional gas reserves.

The Sedco 711-submersible rig arrived on location some 80km off the Mayo coast last week and has been booked for the summer.

Seismic information gathered last year on the Corrib North block has proved to be “very positive”, according to industry sources.

If the field proves commercial, it could result in a significant extension of the Corrib offshore and onshore infrastructure, subject to Government approval.

Vermilion, which bought out Marathon’s share in Corrib last year for a quoted price of $400 million (€330 million), described Corrib North last year as “a four-way dip closure that has the potential to hold about 200 billion cubic feet of gas”.

The Canadian company's chief executive Lorenzo Donadeo told the industry journal, Upstream, that if the well was successful, "the discovery could be tied back to Corrib's infrastructure via two sub-sea wells at a cost of up to $117.8 million.

The current Corrib gas field on the Slyne Basin is estimated to have a 20-year lifespan, with a capability of producing up to 60 per cent of Ireland’s energy needs over five years.

Shell EP Ireland confirmed that it “intended to drill an exploration well” on the site.