Patent ID: 8899333
Filing Date: 2014-12-02
Classification: E21B

Abstract:
1. A subsea device used for semi-submersible rig, comprising a buoyancy force adjustable can, a string of risers, a blowout preventer, a string of tie-back pipes, an inject valve fixed on the top of the can, a vent valve fixed on a side of the can, and a buoyancy force adjustment device connected to the inject valve; the blowout preventer being directly installed on the top of the can, the top of the string of risers being connected to the rig and the bottom of the string of risers being mounted on the blowout preventer; the top of the string of tie-back pipes being fixed to the bottom of the can, the lower end of the string of tie-back pipes being mounted to a wellhead on the seabed through a subsea wellhead apparatus fixed on the seabed and being connected to a formation casing for collecting oil or natural gas stored in formations; and a passage being located in the can to communicate with the blowout preventer and the string of tie-back pipes; wherein the buoyancy force of the can is adjusted with the buoyancy force adjustment device, the inject valve and the vent valve to bear most of the weight of the string of tie-back pipes.