LONDON, Aug 23 (Reuters) - British wholesale gas prices weremixed on Friday morning, with an oversupplied market weighing onwithin-day prices while planned maintenance work boostedday-ahead contracts.
* Within-day gas fell 1.50 pence to 27.50 pencepertherm by 0902 GMT.
* Day-ahead gas was up 0.80 p at 29.50 p/therm.
* Production from the UK Continental Shelf rose by 4 millioncubicmetres (mcm) thanks to the end of maintenance that had affectedBarrow North and St Fergus Shell.
* Flows from Norway along the Langeled pipeline system alsoincreased, rising by 7 mcm.
* However, the uplift will be short-lived. A planned outageat thehuge Troll field and Kollsnes processing plant, into which itfeeds gas, is expected to start at the weekend, reducing flowsby 147 mcm.
* The system was oversupplied by 20.2 mcm, with demandforecast at124.5 mcm and supplies seen at 144.7 mcm, National Grid datashows.
* "Despite the system being loose today due to the rerouteinNorwegian gas to the UK, there is a high possibility forKollsnes maintenance ... starting over weekend to support pricesduring the afternoon today," Refinitiv gas analysts said in adaily note.
* Supplies were also curbed by an unplanned outage at theCulzeangas field, though a resumption in operations began early onFriday, operator Total E&P said in a market update.
* Meanwhile send-out from British liquefied natural gas(LNG)terminals dipped below the levels of a year ago for the firsttime this year, at about 5 mcm, Refinitiv data shows.
* No new LNG tankers are scheduled to arrive in Britain intheforeseeable future. In recent months send-out has peaked atalmost 80 mcm, having been above 40 mcm for most of the year.
* Peak wind power generation is forecast at 7.8 gigawatts(GW) onFriday, down from 9.2 gigawatts (GW) on Thursday, and will fallfurther to about 4.4 GW over the weekend, Elexon forecastsshowed.
* The September gas contract fell 0.54 pence to30.10p/therm.
* The month-ahead contract at the Dutch TTF hubwasdown 0.12 euro at 10.88 euros per megawatt hour.
* The benchmark Dec-19 EU carbon contract was down0.25euro at 25.41 euros a tonne.(Reporting by Sabina ZawadzkiEditing by David Goodman)