Crude oil prices closed mixed Thursday after Hurricane Isaac appeared to have left Gulf of Mexico refiners fairly unscathed and ahead of a keenly anticipated speech by Federal Reserve chief Ben Bernanke. New York\'s main contract, West Texas Intermediate (WTI) light sweet crude for October, fell 94 cents to $94.62 a barrel. In London, Brent North Sea crude for delivery in October edged up 11 cents to $112.65 a barrel. Fears about disruption to supply in the US Gulf from Hurricane Isaac, since downgraded to a tropical storm, had affected prices but in the end proved unfounded, said Sanjeev Gupta, who heads the Asia-Pacific oil and gas practice at Ernst & Young. \"Most of the production facilities were shut down in advance of the storm, but early reports indicated fairly limited supply disruptions, thus taking some of the pressure off prices,\" he told AFP. \"WTI\'s relative weakness thus far... reflects an easing in storm damage concerns to offshore Gulf platforms following Hurricane Isaac\'s landfall yesterday,\" said Sucden analyst Jack Pollard. \"The weather conditions should keep north Gulf production limited for the remainder of the week, though the chance of permanent damage appears to have reduced.\" Chevron said its huge Pascagoula Refinery, located in Mississippi, continues to operate, but was running at a reduced rate Thursday as a precautionary measure until marine transportation returns to normal. Traders\' attention was focused on Friday\'s speech by Bernanke in Jackson Hole, Wyoming, scheduled for 1400 GMT. Markets have been on edge for weeks over whether the Fed chairman will act on the sluggish economy. But with data pointing sideways, few are agreed on whether he will signal fresh stimulus.