Cnooc International has started drilling an appraisal well at its Cragganmore discovery in the West of Shetland.

The Chinese state-owned operator announced in June its intention to drill at the prospect, using the Ocean GreatWhite rig.

According to information on the Oil and Gas Authority’s website, an appraisal well was spudded on Friday, July 19.

Little information has been released on the potential resources at Cragganmore.

However Cnooc, then Nexen, said last year the prospect has “large volume potential” with “uncertain extent and reservoir quality”.

The prospect lies nearby to Total’s Glenlivet and Edradour fields, as well as its flagship Laggan-Tormore development.

Cragganmore was discovered in 2013 by Dong Energy.

The discovery is operated by Cnooc with a 70% stake, while the remaining 30% is held by Ineos.