YET ANOTHER deep-water drilling rig project has run into delays and cost overruns, joining a long list of stricken newbuilding and conversion schemes. Transocean Sedco this week struck a deal with Elf Exploration Angola to buy extra time for construction work on its newbuild semi-submersible Sedco Express. The deal confirms long-lived industry scuttlebutt that the unit, one of two semisubs the company has under construction at French naval yard DCN, was running behind schedule.