Gas-water mixture jet drilling method for coalbed methane production in quincunx radial horizontal wells

Abstract

The invention discloses 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, and using high-pressure gas-water through a radial guide tool. The mixed liquid is jet-drilled into and out of the coal seam along different azimuths and radial directions in one or more groups of radial horizontal holes with a certain diameter and length, and is lowered into these radial holes with diversion holes. High-strength PVC screen pipe with holes, forming quincunx-shaped radial horizontal wells with support and diversion functions, one or more groups (multi-coal seam) quincunx-shaped radial horizontal wells and the well pattern composed of these radial horizontal well groups coalbed methane mining method.

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, long completion period and other shortcomings, but also in order to overcome the coal dust generated during the drilling process of the radial horizontal hole during jet drilling, which seriously blocks the coal seam around the hole wall 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, resulting in failure of radial holes, complex construction control, and high working pressure. In order to more effectively improve the commercial development benefits of coalbed methane wells, the present invention provides a Use tubing (diameter 89mm) as the working string, run radial guide tools into the coal seam section after vertical well reaming, use coiled tubing with high-pressure jet gun, and use high-pressure gas-water mixture as the working medium (can realize under-balanced state), a group of plum blossom-shaped radial horizontal holes are drilled in the coal seam, and high-strength PVC screen pipes with diversion holes are used for diversion and support to prevent the hole from collapsing and clogging. radial horizontal hole

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