The cost of a barrel of North Sea Brent crude hit a record before pulling back Thursday when priced in euros and British pounds, two currencies that have been weakening of late.

WSJ: Rising Demand for Oil Spells More Price Pain

North Sea Brent and WTI, the two benchmark crude oils are both sweet, light.

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It is assessing two kinds of North Sea crude oils that are like Brent called Troll and Duc and is analyzing the need for additional escalators in the assessment process, like adding more grades to the Brent mechanism.

WSJ: Brent Benchmark Is Skewed by Crude Measure

Meanwhile recent maintenance shutdowns in the North Sea have worsened already declining supplies from ageing fields of Brent crude.

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At a time when global stocks of crude are ample, Brent prices reflect the opposite because of falling North Sea output, analysts say.

WSJ: Brent Benchmark Is Skewed by Crude Measure

Dominated by the benchmark price of Brent crude, the black stuff that flowed from what was once the North Sea's biggest-producing field, the work of these PRAs has been looked at in some technical detail by the International Organisation of Securities Commissions (IOSCO).

BBC: Setting prices crudely

It's looked not only at Brent crude but at some other exotic hydrocarbon cocktails - West Texas Intermediate, the Argus Sour Crude Index, Brent Blend or BFOE (the basket of the North Sea's Brent, Forties, Oseberg and Ekofisk), Dubai and Oman, Tapis and Minas, and East Siberia-Pacific Ocean Blend.

BBC: Setting prices crudely