Broken and soft coal seam closed coring drill bit suitable for ground drilling

Abstract

The invention discloses a broken and soft coal seam closed coring drill bit suitable for ground drilling. The coring drill bit comprises an outer drill bit body, an inner drill bit body and a drill bit body; the drill bit body is provided with a three-step hole with the hole diameter sequentially increased from front to back, the outer drill bit body is fixedly arranged on the outer ring wall of the front end of the drill bit body, the outer drill bit body is provided with a plurality of cutting wings, a flow guide groove is formed between two adjacent cutting wings, the inner drill bit body is detachably installed on a small-diameter hole section of the three-step hole, a water hole communicating with the flow guide groove is formed in a first-stage step face between a large-diameter holesection and a larger-diameter hole section of the three-step hole, an annular groove is formed in the larger-diameter hole section of the three-step hole, and the annular groove is used for installing a sealing ring. According to the broken and soft coal seam closed coring drill bit, scouring by drilling fluid to broken coal cores is avoided, the denudation effect by the drill bit wall on the coal cores in the drilling process is reduced, the inner drill bit body enters a coal seam earlier than the outer drill bit body, the mining rate for coal seam closed coring can be increased, and the success rate of coal seam gas content measurement for ground drilling broken and soft coal seam closed coring is increased.

Description

technical field [0001] The invention relates to the technical field of accurate measurement of gas content in sealed cores for ground drilling, and in particular to a sealed core drill bit for broken soft coal seams suitable for ground drilling. Background technique [0002] Due to the broken coal structure, the coalbed methane (gas) escapes quickly in broken soft coal seams. The coalbed methane (gas) content measured by conventional coring methods is lower than the actual coalbed methane content, which may easily lead to inaccurate estimates of coalbed methane resources and coalbed gas. Insufficient awareness of the degree of danger has left hidden dangers for the exploration and development of coalbed methane (gas) resources and the safe production of coal mines. The closed coal seam coring technology for surface drilling can drill coal cores at fixed points and quickly, and can ensure that the coal cores are lifted in the borehole and the airtightness of the ground measur...

AI Technical Summary

Problems solved by technology

Coring with conventional coring bits not only has low drilling efficiency and low coal core collection rate, but also often fails to collect coal core samples from broken and soft coal seams

The main reasons why conventional core bits cannot collect coal core samples from broken soft coal seams are as follows: first, the erosion of the drilling fluid on the coal seam in front of the bit causes the coal body to be washed away; The denudation effect will cause the coal core to be drilled and lost; the third is that the scouring effect of high-pressure water flowing out between the inner wall of the core bit and the core inner cylinder will also cause the loss of the coal core

Therefore, in view of the status quo of broken soft coal seams and closed coring, it is urgent to design and trial-produce a drill bit for ground drilling broken soft coal seam closed coring, so as to solve the problem of low rate of closed coring of broken soft coal seams and no coal cores. Phenomenon

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