Coal bed methane exploring method of spraying gas-water mixed liquid to drill well and forming quincunx radial horizontal well

Abstract

The invention discloses a coal bed methane exploring method belonging to the field of coal bed methane exploring, and in particular relates to a coal bed methane exploring method. In the coal bed methane exploring method, a continuous oil pipe with a high pressure fluid jet gun is used after hole enlargement of a vertical well in a coal bed well section. By means of a radial guide tool, high pressure gas-water mixed liquid is adopted to spray and drill out one group of radial horizontal holes with certain diameter and length or a plurality of groups of vertically distributed radial horizontal holes with the certain diameter and length in a coal bed at different azimuthal angles and along the radial direction. High-strength polyvinyl chloride (PVC) sieve tubes provided with diversion holes are arranged into the radial horizontal holes to form a quincunx radial horizontal well with support and diversion functions, a group or a plurality of groups of (multiple coal beds) quincunx radial horizontal wells and well patterns formed by the radial horizontal wells.

Description

[0001] The invention relates to a coalbed methane mining method in the field of coalbed methane mining, in particular to a method of using a coiled tubing with a high-pressure fluid injection gun to ream a coalbed well section in a vertical well. The water mixture is jet-drilled into and out of a group or multiple groups (multi-coal seams) distributed up and down in the radial direction of the coal seam along different azimuth angles, with a certain diameter and length. A high-strength PVC screen with diversion holes forms a quincunx-shaped radial horizontal well with support and diversion functions. One or more groups (multi-coal seam) quincunx-shaped radial horizontal wells and these radial horizontal wells A coalbed methane mining method composed of a well pattern. Background technique [0002] In the field of coalbed methane exploration and development, vertical fracturing wells, cave wells, and various types of horizontal wells such as "U" wells, "V" wells and different f...

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Problems solved by technology

[0003] In order to overcome the large amount of pulverized coal output in the process of drainage and gas recovery (drainage) caused by vertical fracturing, which leads to the blockage of cracks in the diversion channels in the coal seam, in order to overcome the easy pollution of the coal seam during horizontal well drilling and the easy collapse of the coal seam during drainage Blocking the wellbore and construction is difficult, high cost, and long completion period. In order to overcome the coal dust generated during the jet drilling of the radial horizontal hole, the coal seam around the well wall is seriously blocked and the hole diameter is too small. , especially in the soft coal seam of structural coal and low-rank coal, it is very easy to collapse, causing radial hole failure, complex construction control, and high working pressure. The tubing (diameter 89mm) is used as the working string, and the radial guide tool is lowered into the coal seam well section after the reaming of the vertical well, and the coiled tubing with a high-pressure spray gun is used, and the high-pressure gas-water mixture is used as the working medium ( A group of plum blossom-shaped radial horizontal holes are drilled in the coal seam, and a high-strength PVC screen with diversion holes is used for diversion and support to prevent the borehole from collapsing and blocking the radial horizontal hole

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