The firm said its infill drilling campaign held the potential to unlock enough gas to heat an additional 200,000 UK homes per year from this winter.
Upon completion of the tenth well on the field in the fourth quarter of this year, the Cygnus gas facility will be capable of producing enough gas for some two million UK households.
The Neptune-operated Cygnus field is an important component of the UK North Sea’s energy infrastructure.
The firm’s UK country director, Alan Muirhead, said: “The tenth well is part of the existing Cygnus field development plan and will support additional supplies of much-needed low carbon gas for UK households from this winter.
“Domestic production has a crucial role in supporting UK energy security and Neptune has been working hard to incrementally increase natural gas supplies from its operated assets, including from Cygnus in the UK and from Gjøa in Norway, which is exported via the Flags pipeline to the St Fergus Gas Terminal in the North-east of Scotland.”
Neptune Energy, which was founded by former Centrica boss Sam Laidlaw, is a global exploration and production company with operations across Europe, North Africa and Asia Pacific. It is backed by CIC and funds advised by Carlyle Group and CVC Capital Partners.
In May, the firm said it planned to spend more than $1 billion (£810 million) over the next five years helping to secure energy supplies for the UK.