All these attempts were introduced with the caution that they'd never been tried a mile underwater, where BP's well was gushing oil. Exxon and the other companies on Wednesday promised their equipment will be tested beforehand.The new system draws on lessons learned from BP's efforts and uses some similar equipment. The companies say the equipment shouldn't break down under extreme pressures and depths. The response system will include an array of underwater equipment designed to create a permanent connection and seal over a busted well. It will separate oil from gas and bring it to the surface where the gas can be burned off and the oil can be stored on tankers. The companies say the system could capture up to 100,000 barrels â¿¿ 4.2 million gallons â¿¿ of oil in depths of up to 10,000 feet, twice as deep as the waters BP was operating in. The four were not involved in the Gulf oil spill, but each rely on offshore drilling to generate significant revenue. Shell and Chevron have prominent drilling operations in the Gulf. The system's similarities to what BP has used concerns U.S. Rep. Edward Markey, D-Mass., one of the harshest critics of the industry's disaster planning. While the new system could be deployed rapidly, "the oil companies must do better than BP's current apparatus with a fresh coat of paint," he said. He said the announcement of the containment system could be a positive step, "but it cannot be the industry's last," adding that what's needed are technologies "that will prevent fatal blowouts in the first place." Rex Tillerson, chairman and chief executive officer of ExxonMobil, who has been critical of BP's handling of the well prior to the explosion, echoed that sentiment in a statement announcing the new system. "If we all do our jobs properly, this system will never be used," he said.