(CNBC)
Crude oil prices rose to a more than seven-year peak Friday and recorded a sixth straight weekly gain as geopolitical turmoil exacerbated concerns over tight energy supply. On a weekly basis, the benchmark contracts notched their longest run of gains since October. Brent futures rose 69 cents to settle at $90.03 a barrel, after hitting $91.70, the highest level since October 2014. US crude closed 21 cents higher at $86.82 per barrel, after hitting a seven-year peak of $88.84 during the session. Tight oil supplies pushed the six-month market structure for Brent into steep backwardation of $6.92 a barrel, the widest since 2013. Backwardation exists when contracts for near-term delivery of oil are priced higher than those for later months, encouraging traders to release oil from storage to sell it promptly.