Saudi Arabia increased output to around 9 million barrels a day, almost 1 million bpd above its agreed OPEC quota, as violent unrest slashed exports from Libya but analysts said production had been significantly increased before fighting broke out.
The uprising in Libya has cut its 1.6 million bpd output by half, the International Energy Agency said late in February, while Libya's top oil official has estimated output has fallen by 700,000-750,000 bpd. Libya was the world No.12 exporter before the unrest.
"We believe that Saudi production could be 0.5-1 million bpd higher than the official numbers suggest, which would imply that OPEC spare capacity has already dropped below 2 million bpd," the bank said in a note.
"While the current loss of supply might turn out to be short-lived as production can be restored relatively quickly once the current civil unrest settles down, the real risk is that the remaining spare capacity cannot accommodate an escalation in disruption right now in our view."
Three months ago Goldman Sachs estimated OPEC spare capacity to be around 2.5-3 million bpd.
Last month a senior Saudi source said the kingdom had spare capacity of around 3.5 million bpd.
Brent crude leapt to nearly $120 a barrel last month, its highest since 2008, as escalating violence in Libya choked supply, and the market fretted protests could spread to other OPEC countries.
