Brent crude has dropped to its lowest level in more than a decade, surpassing the lows hit at the depths of the financial crisis, as the market groans under the weight of over-abundant supply.  The international oil marker dipped 2 per cent to $36.17 a barrel overnight, its lowest level since 2004 and below the $36.20 reached on Christmas Eve in 2008.  West Texas Intermediate, the US oil benchmark, was down 1 per cent to $34.37, but still above its financial crisis low of $32.40 hit almost seven years ago.  Oil prices have dropped more than 15 per cent since a rancorous Opec meeting earlier this month that exposed the organisation’s inability to tackle a global oil glut, which is growing by as much as 2m barrels a day, according to some estimates.