Royal Dutch Shell PLC in 2008 spent $2.1 billion on Chukchi Sea leases and estimates it has spent a total of nearly $5 billion on drilling efforts there and in the Beaufort.Shell Alaska spokesman Curtis Smith said the company has a long, successful history of working offshore in Alaska and is confident it can build another multidecade business in the Arctic. "Our success here is not by accident," Smith said. "We know how to work in regions like this. Having said that, when flawless execution does not happen, you learn from it, and we will." The drill ship that operated in the Beaufort Sea, the Kulluk, a circular barge with a funnel-shape hull and no propulsion system, ran ashore Monday on Sitkalidak Island, which is near the larger Kodiak Island in the gulf. The ship had left Dutch Harbor in the Aleutian Island under tow behind the 360-foot anchor handler Aiviq on Dec. 22. It was making its way to a Pacific Northwest shipyard for maintenance and upgrades when it ran into a vicious storm â¿¿ a fairly routine winter event for Alaska waters. The tow line snapped Dec. 27. Shell vessels and the Coast Guard reattached tow lines at least four times. High wind and seas that approached 50 feet frustrated efforts to control the rig, and it ran aground on a sand and gravel beach. Shell, the drill ship operators and transit experts, and the Coast Guard are planning the salvage operation. Calmer weather conditions on Wednesday allowed a team of six salvage experts to be lowered by a helicopter to the Kulluk to conduct a three-hour structural assessment. Information the team gathered will be used for the final salvage plans, officials said late Wednesday in a release. Also taken to the Kulluk was a state-owned emergency towing system for use in the operation.