By Oleg Vukmanovic
MILAN, Aug 21 (Reuters) - Gas giant Qatar has agreed withPetroChina to skew deliveries under an existing long-termliquefied natural gas (LNG) supply deal towards the peak demandwinter period, a shift likely to weigh on global spot prices.
The concession to PetroChina fits Qatar's recent pattern ofadapting to long-term buyers needs, as it becomes morecommercially savvy and active on spot markets, to hold onto itsshare of the prized Asian market.
Qatargas, the world's biggest LNG exporter, has skewed the 3million tonnes of LNG annually contracted to PetroChina towardsthe winter, two sources with knowledge of the matter said.
The deal only extends to this winter, one of the sourcessaid, but could be renewed when PetroChina and Qatar discusstheir delivery programme for 2016 later this year.
Supplies under the 25-year deal, which began in 2011 and inwhich Shell is also involved, previously arrivedsteadily throughout the year.
PetroChina requires more LNG in winter because its threeimport terminals are situated on China's northern coast, mostexposed to cold weather.
Chinese imports from Qatar have already fallen 42 percent inthe first seven months of 2015 compared with last year,illustrating the impact of the changes.
SPOT MARKET IMPACT
With PetroChina's winter gas demand now largely filledthrough Qatari diversions, global LNG markets should see lessChinese buying on spot markets this winter, putting pressure onprices, a trader said.
In past years Chinese winter buying sparked several spot LNGprice rallies, notably in winter 2013/2014.
But weak global demand and rising supply have sincedepressed prices to five-year lows at $7.90 per mmBtu, down60-percent from February highs last year.
"This just shows how even established suppliers are comingunder pressure in this market," a senior commodities financebanker told Reuters.
RasGas, a sister company of QatarGas, is already embroiledin talks with Gail India over changing its long-term contracts,a source at the company told Reuters.
While Qatar has a track record of meeting Chinese buyershalf-way, such as by arranging short-term supplies foradditional winter needs, it has generally proven reticent tomeddle with long-term LNG contracts that form the bedrock of itsbusiness.
The latest supply rejig with PetroChina does not constitutea change to the underlying long-term sales agreement.
But emerging pressures bearing down upon Qatar's long-termgas sales strategy, especially competing suppliers in Australiaand the United States, are forcing it to cut sweeter deals tolock-up the remainder of its unsold gas, sources have said.
Qatar is currently in talks with Pakistan to seal a majornew export deal.
(Editing by David Evans)