Drill string disconnection and re-hookup device for non-riser dual-gradient drilling operation

Abstract

The invention discloses a drill string disconnection and re-hookup device for a non-riser dual-gradient drilling operation. The device comprises a releasing mechanism, a pin returning mechanism, a plugging mechanism, a male and female body re-hookup mechanism and a re-hookup guide auxiliary mechanism; releasing of a drill string is realized through the releasing mechanism by shearing a pin; duringa releasing process of the drill string, the sheared pin is pushed out by the pin returning mechanism to realize hole cleaning; the plugging mechanism consists of a valve clack and is used for plugging high-pressure fluids in the drill string after releasing; the main function of the male and female body re-hookup mechanism is to push the pin to fill a pin hole; and the main function of the re-hookup guide auxiliary mechanism is to realize the guide during the re-hookup of a male body and a female body. The drill string disconnection and re-hookup device for the non-riser dual-gradient drilling operation has the effects that the drill string is released in emergency, and the safety of the drilling operation is guaranteed; plugging of the underground high-pressure fluids is completed, andthe pollution of seawater caused by flowing of the high-pressure fluids from the drill string into the seawater is prevented; the reliable re-hookup after disconnection is realized, and subsequent drilling operation is carried out; and the sealing mechanism for the underground high-pressure fluids in a re-hookup process is provided, and the danger caused by instantaneous flowing of the undergroundhigh-pressure fluids is prevented.

Description

technical field [0001] The invention is designed for the technical field of deep sea underwater oil and gas exploitation, and in particular relates to a riser-free dual-gradient drilling drill string uncoupling tie-back device. Background technique [0002] China's deep waters are rich in oil and gas resources, and no matter whether they are explored or exploited, deep-water drilling operations are inseparable. Deep-sea dual-gradient drilling operations include deep-water drilling operations without risers and deep-water drilling operations with risers. Riserless drilling technology, as an emerging deep-water oil and gas reservoir development technology, can well make up for the shortcomings of traditional marine riser drilling technology in deep water and improve drilling efficiency. [0003] However, in the process of deepwater drilling without riser, the drill string is directly exposed to the sea water, and it is vulnerable to the impact of wind and waves in the marine e...

AI Technical Summary

Problems solved by technology

[0003] However, in the process of deepwater drilling without riser, the drill string is directly exposed to the sea water, and it is vulnerable to the impact of wind and waves in the marine environment and complex deformation under the action of the movement of the floating drilling platform, resulting in damage to the drill string and pipe string. The leakage of oil and gas will bring pollution to the marine environment; moreover, because there are a large number of equipment and staff on the drilling platform or drilling ship, if it cannot be separated from the lower drill string and pipe string in time in this emergency, it will lead to Larger safety accidents and serious economic losses

At present, the existing safety protection device is released by cutting the pin, and the internal high-pressure fluid is blocked by driving the ball valve, but the sealing effect of the ball valve is not ideal, and the processing accuracy is high.

At the same time, there is no relevant device to realize the drill string tie-back and channel re-opening functions

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