The Songa Mercur is a semi-submersible drilling rig designed by Friede & Goldman, ex Shelf 10 and La Muralla. It is capable of drilling in water up to a depth of 1,200 feet (370 m).In May 2006, Songa Offshore signed a nine-month contract with Chevron to use the rig in Australia. A contract was later signed with Santos Ltd., which was originally nine months and was extended to a year and then a year and a half.