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* Urges Platts to reconsider its position on certain points
* Platts consulting until March 10 on changes to Brent
* Industry seen adopting common standard
By Alex Lawler
LONDON, March 8 (Reuters) - BP Plc has supportedaspects of a proposal made by Royal Dutch Shell overreforming the benchmark price assessment for Brent crude, ratherthan those of pricing agency Platts.
Oil companies and Platts want to boost the credibility ofBrent, a benchmark for oil trade. Critics say cash Brent isprone to manipulation because it is based on dwindling suppliesof four North Sea crudes, sometimes leading to higher prices.
Shell and Platts put forward differing proposals last month,and the prospect of two standards led to concerns about a splitin liquidity in the Brent-Forties-Oseberg-Ekofisk (BFOE) forwardmarket, which could damage the benchmark's credibility.
The cheapest of the four BFOE crudes - usually Fortiesbecause it is of lower quality - sets the value of dated Brent,the benchmark used to price cargoes in Europe, the Middle East,Africa and parts of Asia.
In a March 6 letter to Platts made available by BP, BPresponded to the Platts' proposal to apply quality premiums totwo of the crudes deliverable into BFOE forward contracts thathelp establish the Brent price.
BP said it still supported Shell's suggestion over thetimeframe used to calculate quality premiums and disagreed withPlatts' proposal not to apply a premium if price differencesbetween crude grades were less than 50 cents a barrel.
"For these reasons we are not able to support yourmodifications to Shell's proposal and would urge you toreconsider your position in this regard," BP's letter said withrespect to those two points.
BP also supported Shell's proposal on the size of thequality premium applied to Oseberg crude - 25 percent ratherthan the 50 percent proposed by Platts - although adding thatits concern was less than over the first two issues.
Oil traders say the introduction of quality premiums wouldencourage traders to deliver the full range of eligible crudesinto the BFOE contracts, increasing liquidity. At present, Forties most often tends to be delivered.
Platts, a unit of McGraw-Hill which provides clientswith price benchmarks in the energy markets, is seeking input onits proposal until March 10.
Trade sources expect the industry to settle on a singlestandard.
"BP and Shell have made some statements, but they seem to belooking for concessions from Platts," a senior trader said. "Iguess it is really now Platts' turn to comment."
BP said it agreed to implement changes for cargoes loadingin June 2013 as proposed by Platts, a month later than Shelloriginally suggested.
