Offshore unit and method of installing wellhead platform using the offshore unit

摘要

The present invention relates to an offshore unit (10, 60, 62, 64, 58, 70) which includes hull (12) and/or deck frame (52), a mat (14) attached to at least one connecting leg (16) or a spud can (50) attached to each of at least one connecting leg or lower hull (18) attached to at least one connecting means (66), a wellhead deck (24) is removeably attached to the hull (12) and/or deck frame (52) and a sub-sea clamp in conjunction with a caisson (20) or a sub-sea conductor frame (32) removeably attached to the mat (14) or to the at least one connecting leg (16), where a spud can (50) is attached to each of the at least one connecting leg, or to the lower hull (18). The offshore unit is relocatable and is a platform or a rig capable of performing drilling, production, construction, accommodation, hook-up and commissioning or a combination of any of these functions thereof. The offshore unit is a self elevating mobile platform (10, 60, 62, 64) or submersible platform (70) or semi-submersible platform (58). The present invention also relates to a method of installing a wellhead platform (22) which includes a wellhead deck (24), sub-sea conductor frame (32) and at least one conductor (26) using a offshore unit (10, 60, 62, 64, 58, 70). The method includes transporting the offshore unit (10, 60, 62, 64, 58, 70) to offshore installation site, installing the offshore unit, installing at least one conductor (26) through the wellhead deck (24) and sub-sea conductor frame (32) until the at least one conductor (26) penetrate through soil layers to target penetration and securing the wellhead deck (24) to the at least one conductor (26). Alternatively, a sub-sea clamp in conjunction with a caisson can be pre-installed instead of the sub-sea conductor frame and offshore installed conductor. The present invention also relates to method of demobilizing a self elevating mobile platform (10, 60, 62, 64). Besides that, the present invention relates to method of installing a wellhead platform (22) for exploring hydrocarbon below sea bed which includes a wellhead deck (24) and sub-sea conductor frame (32) using a offshore unit.