NEW YORK -- Is new shale oil development from North Dakota and south Texas isolating the United States crude oil market from the rest of the world?

Recent pricing trends in oil futures contracts suggest as much: Prices for a popular domestic contract have plunged while oil prices per a United Kingdom-based contract stay well above $100 a barrel.

But market players -- at least for now -- think the phenomenon is temporary, and that the price differential will narrow once physical supply constraints on both sides of the Atlantic are overcome.

In recent months prices for the world's two most popular energy commodities contracts, West Texas Intermediate (WTI) light sweet crude oil and Brent crude, have been drifting apart. In the recent past, Brent crude contracts have generally sold at a $5 a barrel premium over WTI for some time, but lately that split has become much wider as WTI prices have drifted downward while Brent prices have held steady.

On some days the price differential has approached $30, as WTI prices flirted with the $80-per-barrel mark while trading in Brent kept it much higher. Today the spread is around $25, with Brent futures for December delivery selling for just above $111 per barrel, while WTI November delivery futures trades are at around $86 per barrel.

The divergent pricing trend echoes the split between the markets for natural gas, divided between North America and the rest of the world with the popularity of shale gas production. While demand from emerging markets has buoyed international prices for liquefied natural gas (LNG), the shale gas boom in the United States has kept prices in North America lower.

Emergence of a large shale oil industry in the United States, with booming production in North Dakota in particular, could be having a similar impact, market players say.

Oil traders at the New York Mercantile Exchange (NYMEX) say the divergence of the contracts' prices reflects the physical divergence -- abundant supplies at the WTI hub in Cushing, Okla., contrasted with struggling North Sea output and the continuation of Libya's supply cutoff.

Growing Russian exports to East Asia also appears to be diverting some crude that would traditionally go to Europe, experts say.

But traders warn the split won't last once new pipelines that would divert more of the Cushing supply to the Gulf of Mexico gets built.

"They've got pipelines planned that are going to help alleviate and bring some of the barrels that exclusively go to Cushing, Okla., further down into the Gulf," said Pete Donovan at Vantage Trading. "There are a lot of refineries down on the U.S. Gulf Coast, and to bring barrels down a little more efficiently down from Cushing, Oklahoma, will tie the WTI market in closer to some of these other grades.

"It's a function of time," Donovan added.

'Verdict' on WTI as benchmark

Still, the widening gap between the two futures markets has not gone unnoticed by major market watchers. Some banks are speculating that abundant North American supply could see WTI losing its status as the global crude oil benchmark.

Last week operators of the Dow Jones-UBS Commodity Index (DJUBSCI), which follows price trends for a basket of energy, metals and agricultural goods, announced a new weighting of the index for 2012 that for the first time includes Brent crude. Beginning in January, WTI will still make up about 10 percent of the entire index, while Brent will assume 5 percent of the share and about a third of the energy component of the index.

A spokesman for Dow Jones Indexes declined to offer details on why the decision was made, only pointing to the statement issued after the index's supervisory committee announced the change, noting that the new weighting was an "acknowledgment of Brent's economic significance as a global benchmark, the liquidity of the Brent futures contract and the actual production of the commodity itself."

Meanwhile analysts at Barclays Capital, now one of the biggest commodities players on Wall Street after its acquisition of much of Lehman Brothers Holdings, offered their own thoughts on why the WTI's weight on the Dow Jones-UBS index was reduced.

"The move is a verdict on the declining usefulness of WTI as a global crude oil benchmark," Barclays analysts Kevin Norrish and Amrita Sen wrote in a note to clients. "The fact that the DJUBSCI is prepared to make such a change, despite the costs and difficulties involved, suggests that it does not expect the dislocations that affected crude oil pricing in the U.S. Midwest to ease anytime soon."

Barlcays analysts predict that other commodity index trackers will soon follow, most notably Standard & Poors GSCI.

Still, NYMEX traders believe it is too soon to tell whether the growth of shale oil production in the United States will do to the crude oil markets what shale gas technology did to natural gas trading.

"What happened with us in the natural gas market is a technological breakthrough that inundated the market with supply when it was very tight, and I don't think that's the case between Brent and WTI," said Raymond Carbone, president of Paramount Options. "I still think the natural gas market is a much, much bigger deal in the way that supply issue has just run amok really."

Analysts at the credit rating agency Fitch Ratings agree.

"As Libyan production comes back on line and European demand growth slows, the potential exists for global demand to decline relative to supply, potentially pushing down crude prices and narrowing the spread between the Brent and West Texas Intermediate benchmarks," Fitch said in a recent note.