Transocean Sedco Forex Inc., the world's biggest offshore driller, said one of its rigs was damaged by a gas blowout while drilling a well offshore Indonesia for Australia's Santos Ltd. Transocean said all 92 crewmen aboard the jack-up rig Trident IX were evacuated without injury to a service vessel. It said it expected insurance to cover the cost of the damage that appeared to be limited to the drill floor area. The incident which occurred on Thursday in the Madura Straits, offshore East Java, was caused by an uncontrollable release of natural gas which subsequently ignited.