Pipe body structure of step type hole protecting pipe for gas extraction hole in soft coal bed

Abstract

A pipe body structure of a step type hole protecting pipe for a gas extraction hole in a soft coal bed, and belongs to the hole protecting pipe. The hole protecting pipe comprises multiple groups of pipes, which are connected from the front end to the tail end in sequence; the diameters of the pipes in different groups are different, the diameters of the pipes in each group of pipes from the front end to the tail end of the hole protecting pipe are reduced in sequence, and every two adjacent pipes in different groups are connected through a reducer pipe; the whole profile of the hole supporting pipe is of a step type structure with a gradually changed diameter; the diameters of the pipes in the same group are the same, and the lengths of the pipes are the same; sieve pores are not formed in the pipe walls of one group of pipes at the most front end but are formed in the pipe walls of the rest groups of pipes, and the pore diameters of the sieve pores in the pipes in the same group are the same; the number of the sieve pores in each group is reduced from the front end to the tail end in sequence; the diameters of the sieve pores in each group are reduced from the front end to the tail end in sequence, the minimal diameter is 4 mm, and the maximal diameter is 10 mm; and the sieve pores are externally wound with gauzes. The pipe body structure has the advantages as follows: the structure is simple, the hole protecting pipe is not easily blocked and is more easily fed in a deflected drilled hole due to large flexibility, the hole protecting length is long, and the gas extraction efficiency is high at the same time. Therefore, the pipe body structure is suitable for the gas extraction hole in the soft easily-collapsed coal bed.

Description

technical field [0001] The invention relates to a borehole protection pipe, in particular to a pipe body structure of a stepped type borehole protection pipe for a gas extraction hole in a soft coal seam. technical background [0002] The Interim Provisions on Standards of Gas Drainage in Coal Mine (2012) require that mines with serious gas disasters must conduct gas drainage and achieve drainage standards. However, the proportion of soft coal seams in my country is relatively large, and the collapse of soft coal seams is a major problem restricting gas drainage, which seriously hinders the process of mine drainage reaching the standard. At present, there are few effective technical measures to prevent hole collapse in soft coal seams, and the method of sending protective hole pipes into the gas drainage holes is mainly adopted. The average depth of drilling holes for gas drainage in bedding in my country has reached more than 100 meters. Due to the influence of soft and ha...

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Problems solved by technology

[0003] The purpose of the present invention is to provide a pipe body structure of a ladder-type borehole protection pipe for gas drainage holes in soft coal seams, so as to solve the problems that the deflection holes in soft coal seams are easily blocked when entering the borehole protection pipes and the gas drainage holes are easy to collapse, which makes it difficult to extract gas. question

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