Buoyant device used for blowout preventer in deepwater drilling water

Abstract

The invention relates to a buoyancy device for a blowout preventer in the deep-water well drilling water, which is characterized in that, the device comprises a blowout preventer in the well drilling water that is 80-100 m below the water level, and a buoyancy cabin connected with the blowout preventer. The buoyancy cabin is separated into a plurality of mutually enclosed chambers; an ordinary water-insolating pipe connected with the well-drilling platform passes through the center of the buoyancy cabin, and is connected with the upper end of the buoyancy cabin through an ordinary disengaging mechanism; below the blowout preventer, a ballast tank is arranged, the center of which is connected with an upper wellhead through the upper end of a stress joint, the lower end of which is connected with a hi-pressure water-isolating pipe, the perimeter of which is looped with a buoyancy block; the inside of the ballast tank is separated into a plurality of mutually enclosed chambers; in the ballast tank, a set of ordinary ballast system is arranged, which is connected with the control system of the well-drilling platform through an umbitical cable. The invention can reduce the center of gravity of the buoyancy device for the blowout preventer in the whole well-drilling system, has the advantages of the high adaptability, the good performance and the low cost, etc., and can be widely used in deep-water well drilling.

Description

technical field [0001] The invention relates to a buoyancy device for underwater drilling, in particular to a buoyancy device for a blowout preventer in deep water drilling. Background technique [0002] There are generally three types of deepwater drilling devices, conventional drilling devices with a blowout preventer (BOP) placed at the seabed mud line, devices with a blowout preventer in water and devices with a blowout preventer on water. [0003] In conventional drilling equipment, the blowout preventer is placed on the seabed, and the drilling ship and the subsea wellhead are connected by a riser. With the increase of water depth, the conventional underwater drilling method with BOP is facing great challenges. In order to overcome the shortcomings of conventional deepwater drilling devices with blowout preventers installed underwater, a drilling device with blowout preventers installed above water (SBOP system) has been developed in recent years. Drilling devices wi...

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Problems solved by technology

[0005] (1) Due to the influence of the force state of the system, the ABS system cannot withstand too much flow velocity, and the buoy is installed deep underwater (250 meters to 300 meters), which has high requirements on the system and is inconvenient to operate

[0006] (2) The size of the buoy is very large, the installation of the buoy is very time-consuming, and the cost of manufacturing is also high

[0007] (3) Due to the large weight of the buoy itself (up to 379.1 tons), it also needs to bear all the weight of the blowout preventer and the lower return pipe, which needs to provide sufficient buoyancy, so the size of the buoy is very large (diameter of nearly 20 meters , 10 meters high), so that its water depth is limited, and the maximum water depth is 1500 meters

[0008] (4) Since the blowout preventer sits directly on the buoy, and the weight of the blowout preventer is very heavy, the center of gravity of the system composed of the buoy and the blowout preventer is high, and the stability of the system is not good, so it is harmful to the safety and operation of the system. have had a large negative impact on

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