The Helix Producer I oil production vessel and the Helix Express support vessel owned by Helix Energy Solutions Group and leased by BP Plc remain idle from containment efforts as test continue for the cap on the BP Plc MC252 well site in the Gulf of Mexico off the coast of Louisiana, U.S., on Sunday, July 18, 2010. BP Plc said that a pressure test on its damaged Macondo well halted the flow of oil into the Gulf for the first time in three months. The oil spill, the biggest in U.S. history, had been spewing 35,000 to 60,000 barrels of oil a day since the drilling rig exploded on April 20. Photographer: Derick E. Hingle/Bloomberg