UK GAS-Prices dip as Norwegian, LNG supply surge weighs

* Within-day gas down 0.45 p/therm at 29.2 p

* Norwegian flows surge to 52 mcm from 12 mcm

May 16 (Reuters) - British prompt gas prices slid on Monday as supplies from Norway and liquefied natural gas (LNG) terminals surged while demand was relatively subdued.

Gas for within-day delivery fell 0.45 pence per therm by 0846 GMT to 29.20 p/therm, weighed down by an oversupplied transmission network and two additional LNG shipments announced for Britain since late last week.

Gas for Tuesday delivery fell 0.25 p/therm to 30.05 p/therm.

"Total UK Continental Shelf supply has also increased from recent averages, with flows into Bacton SEAL (pipeline) looking to have fully recovered from the unplanned issues affecting operations last week," Marcel Boonaert, head of trading and portfolio at Wingas UK, said.

Norwegian supplies through the Langeled pipeline rebounded to highs of 52 mcm/day on Monday after slumping to 12 mcm/day early in the morning, while contributions from LNG terminals also steadied at high levels.

Total (LSE: 524773.L - news) output from the South Hook and Dragon LNG terminals reached 50 mcm/day, with 10 mcm/day of that coming from Dragon, a terminal which typically contributes little.

UK gas demand was forecast at 220.8 mcm/day - 40 mcm above the seasonal norm as generators burnt more gas to produce electricity - while supply stood at 238.6 mcm/day, National Grid (LSE: NG.L - news) data showed.

That leaves the UK gas system oversupplied by 18 mcm/day.

"If Langeled flows do not fall tomorrow the physical system will again be oversupplied, or the (UK gas price) will drop to incentivise a surge in exports," analysts at Thomson Reuters (Dusseldorf: TOC.DU - news) said.

Gas for delivery in June rose by 0.15 pence to 29.25 pence per therm.

In the Netherlands' gas market, the day-ahead price at the TTF hub was unchanged compared with closing levels on Friday, trading at 12.90 euros per megawatt-hour.

In Europe's carbon market, the front-year EU Allowance price inched up by 0.09 euro to 5.94 euros per tonne. (Reporting by Oleg Vukmanovic; Editing by Adrian Croft)