Loose-soft rock soil stratum reverse circulation casing-following drilling tool and drilling process

Abstract

The invention discloses a loose-soft rock soil stratum reverse circulation casing-following drilling tool and a drilling process. The drilling tool is of a coaxial three-passage structure and comprises a double-wall drilling stem, an auger stem, a drilling bit, a casing and a casing shoe, a central hole of an inner tube of the double-wall drilling stem and a central hole of an inner tube of the auger stem form a slag discharging passage, an annular gap between the inner tube of the auger stem and an outer tube of the auger stem forms an air incoming passage, and an annular gap between the outer tube of the auger stem and the casing forms an outer ring passage; compressed air enters the drilling bit through the air incoming passage and then is diverted and used for assisting a cutting bladeto break a stratum and realize reverse circulation deslagging. Drillings suspended in the outer ring passage go up along spiral blades, enters a deslagging passage through a deslagging window and then returns to the ground surface. Reverse circulation deslagging through a fluid medium and deslagging assisted by the spiral blades are adopted in the process of drilling, so that casing-following drilling is realized to protect hole walls, the problems of bit burying and difficulty in deslagging and hole forming in the process of loose-soft rock soil drilling can be solved, and integration of drilling, collapse preventing, dedusting and wall protecting is realized.

Description

technical field [0001] The invention relates to a reverse circulation follow pipe drilling tool used in soft rock and soil layers, in particular to a drill tool and a drilling process for synchronous operation of reverse circulation slag discharge, auger drilling powder discharge and concentric follow pipe drilling. Background technique [0002] When drilling in soft rock and soil layers such as loose, poor cementation, easy to break, and easy to hydrate, the construction is difficult, and problems such as difficult coring, difficult hole formation, and hole wall collapse are often encountered. The drilling effect is not ideal. The main reason is The reason is that during the construction process, the drilling is easy to collapse while drilling, the amount of slag discharge is large, and accidents such as drill sticking, clamping and buried drilling may also occur, resulting in low drilling efficiency. Therefore, there is a need for a drilling technology that can not only so...

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Problems solved by technology

[0003] Chinese patent document CN201310566830.6 discloses a double-layer internal slag discharge and anti-blocking drilling tool and its use method for drilling into soft and outburst coal seams, including a double-layer internal slag discharge and anti-blocking drill pipe, a central return drill bit, a rotary sealing water supply device, etc. , the rotary sealing water supply device is connected with the double-layer internal slag discharge and anti-blocking drill pipe on the drilling rig, and the central return drill bit is installed at the front end of the drill pipe. tube, but the structure of the drill pipe body is complicated, the processing is difficult, and the strength is low

However, the annular gap between the drill bit and the drill pipe is relatively large, and the reverse circulation is unstable, which still cannot solve the problem of easy hole collapse after lifting the drill

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