Coiled tubing perforation segmental fracturing method in long borehole casing for gas drainage in coal mine

Abstract

A continuous pipe perforation fracturing method in a long borehole casing for underground gas drainage in a coal mine, comprising: step 1: in the coal mine, from a mudstone or sandstone roof at a certain distance from the top boundary of a broken and soft coal seam or from a hard rock of a broken and soft coal seam Construction of long boreholes for gas drainage in layered or hard coal seams with good coal structure; Step 2: Insert guide shoe and rigid casing; Step 3: Annular space between long borehole and rigid casing for gas drainage Carry out cement slurry plugging and solidification; Step 4: use coiled tubing to drag the packer to pack and segment, injectors to blast and perforate, and annulus between coiled tubing and casing to perform fracturing; Step 5: Start out of the fracturing tool, and the fracturing fluid is sprayed in a unified manner; the present invention can overcome the difficulty in forming holes in gas drainage drilling, uncertain location of fracturing crack initiation, short extension of fracturing cracks, poor fracturing reconstruction effect, and poor pumping efficiency. In order to solve the problems such as small and uneven mining influence range and short drainage duration, long drilling holes and multi-stage precise segmental fracturing for gas drainage are realized.

Description

technical field [0001] The invention relates to the technical field of gas control, in particular to a continuous tube perforation segmental fracturing method in long borehole casings for gas drainage in coal mines. Background technique [0002] Among all kinds of coal mine disasters, gas disaster is the biggest disaster in my country's coal mine safety production. Therefore, coal seam gas must be pre-drained in advance before coal mining to ensure safe and efficient production of coal mines. [0003] At present, the pre-drainage of coal seam gas in underground coal mines mainly adopts the methods of drilling through the bed and drilling along the bed. In order to improve the air permeability of the coal reservoir, hydraulic fracturing measures have been adopted, which has achieved certain results, but the following problems still exist: [0004] (1) It is difficult to drill gas drainage holes in broken and soft coal seams, and the drilling depth is shallow; when drilling ga...

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Problems solved by technology

[0008] The purpose of the present invention is to provide a continuous pipe perforation segmental fracturing method in the long borehole casing for underground gas drainage in coal mines, which can overcome the problem of gas drainage drilling along the coal seam in broken and soft coal seams existing in the current underground gas pre-drainage in coal mines Difficulty in forming holes, short extension of open-hole full-hole fracturing fractures, uncertain location of fracturing fractures, small and uneven drainage influence range, poor drainage effect, short duration, etc., to achieve long drilling for gas drainage Hole formation and multi-stage precise staged fracturing

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