Chevron Corp. is assessing the impact on the development timetable of its North Nemba oilfield off the Angola coast after the sinking of the production platform on route from South Korea. The $175 million dollar structure was being shipped by the vessel Mighty Servant 2 early last week when it capsized near the Indonesian island of Singkep with the loss of four crew members. The so-called topside production platform is 230 ft. long, 105 ft. wide, 150 ft. tall and took 24 months to design and build. The vessel was enroute from the South Korean port of Okpo to Angola, having fueled in Singapore, when it began taking on water and sank. Chevron spokesman Fred Gorrell said the company was fully covered by insurance to replace the platform.