Central slag ejection suction drilling tool for drilling in soft formations and its application method

Abstract

The invention discloses an injection type suction drilling tool for residual removal of a drilling center of a weak formation. The drilling tool comprises an air inlet pipe, a cutting removal pipe, a power head and a drill rod, wherein a cutting removal passage and an air inlet passage are formed in the drill rod; an injection type suction drill bit is arranged at the front end of the drill rod; cutting heads are arranged on the end part of the injection type suction drill bit; cutting inlets are formed in the top sidewall of the injection type suction drill bit; injection holes are formed in the inner sidewalls of the cutting heads; high-pressure injection passages are formed in the injection type suction drill bit. According to the drilling tool, a negative pressure area is formed in the cutting removal passage by jetting of the high-pressure injection passages in the cutting removal passage of the center, a suction effect on drilling cuttings is achieved by the cutting inlets, a stirring effect on the bottom of a borehole is achieved by air jets injected by the injection holes, and the drilling cuttings at the bottom of the borehole are driven to be transferred into the cutting holes, and are promoted to enter the cutting removal passage of the center through the cutting inlets, so that the problems of jamming of the drilling tool, burying of the drilling tool, difficulty in removal of the cuttings in the borehole and the like in an existing coal bed gas exhaust drilling process are solved, the drilling efficiency is greatly improved, and the drilling depth is greatly increased.

Description

technical field [0001] The invention belongs to the technical field of special methods or equipment for drilling, and in particular relates to an ejector-type suction drilling tool for slag discharge in the drilling center of soft formations and its application method. Background technique [0002] Coalbed methane has been widely concerned as an unconventional natural gas energy source and has an important impact on underground coalbed gas outbursts. The use of drilling methods to carry out advanced drilling in the coal seam working face and implement coalbed gas drainage operations is the key to realize the utilization and prevention of coalbed methane. The main method of underground coal seam gas outburst. The existing coal seam drilling adopts traditional positive circulation drilling technology and tools. Due to the development of coal seam cracks and soft texture, during the drilling process, the drilling flushing medium enters from the center of the drilling tool. Duri...

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Problems solved by technology

[0005] In view of this, the object of the present invention is to provide a kind of ejection type suction drilling tool for drilling center slag discharge in soft formation and its use method. The drilling tool jets into the central slag discharge channel through the high-pressure injection channel, forming a negative pressure area in the central slag discharge channel, and produces a suction effect on the drilling cuttings at the bottom of the drilling hole through the slag inlet hole on the side of the drill bit, and sucks the drilling cuttings into The slag discharge is carried out in the central slag discharge channel, and at the same time, the jet air ejected from the injection hole on the side of the cutter head is used to stir the bottom of the drilling hole, and push the drilling cuttings at the bottom of the hole to move into the slag inlet hole, so as to promote the cuttings at the bottom of the hole Enter the central slag discharge channel through the slag inlet hole, improve the slag inlet efficiency of the slag inlet hole, and solve the problems encountered in the drilling process of the existing coal seam gas pumping and drainage holes, such as stuck drill, buried drill and difficult slag discharge in the hole. Improve drilling efficiency and drilling depth

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