Air-lift reverse circulation drilling system used in deep water without marine riser and method thereof

Abstract

The invention relates to an air-lift reverse circulation drilling system used in deep water without marine riser and method thereof. The system includes a slurry injection system and an air-lift reverse circulation coreing drilling system; the slurry injection system includes a return cone, an injection pipe, a slurry injection pump and a slurry tank which are sequentially connected; the air-liftreverse circulation coring drilling system comprises an air compressor, an air-water faucet, a double-wall drill rod, an air-water mixer and a single-wall drill rod. The air compressor is connected with the air-water faucet. The lower end of the air-water faucet is connected with the double-wall drill rod. The lower end of the double-wall drill rod is respectively connected with the air-water mixer. The lower end of the air-water mixer is connected with the single-wall drill rod. The return cone is arranged on the outer wall of the drill rod connection. The system does not need a water-proof measure, realizes slurry circulation and well wall protection during drilling, and can be applied to any water depth; air-lift reverse circulation principle is used to convey core and debris so as to reduce construction time and cost; the requirements on the slurry injection pump is reduced and the reliability is good.

Description

technical field [0001] The invention relates to the technical field of oil and gas drilling, in particular to a riserless gas lift reverse circulation drilling system and method for deep water. Background technique [0002] Nowadays, the water depth involved in oil and gas exploration is getting deeper and deeper, and the drilling depth even exceeds several thousand meters. In conventional offshore deepwater drilling, positive circulation closed-circuit drilling with risers or positive circulation open-circuit drilling without risers are usually used. The above findings Some drilling systems and methods have deficiencies: 1) Riser drilling system is complex and complicated to operate, and the load acts on the soft formation at the wellhead, which affects the stability of the wellhead, and the mud (also known as drilling fluid) is kept in a closed circuit in the conventional riser. When the mud circulation increases, the pressure drop of the mud circulation increases, which g...

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Problems solved by technology

[0003] Aiming at the deficiencies of the prior art, the present invention provides a riser-free rapid coring drilling system based on circulating drilling fluid, which can solve the problem of difficult drilling in deep water environment, especially the problem of requiring high energy of the injection pump

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