Production increasing method of coalbed gas

Abstract

The embodiment of the invention discloses a production increasing method of coalbed gas, comprising the following steps of: controlling a horizontal-section well bore to be a non-bifurcation well bore and to communicate with a distal vertical well under the condition that the overall angle change rate of the horizontal-section well bore trace is within 10 degrees / 30m when drilling the horizontal section of the well bore; mounting a horizontal-section completion casing along a second-spudding casing after the horizontal-section well bore is finished; after the mounting of the horizontal-section completion casing is finished, hydraulically spraying on the wall of the horizontal casing to drill branch well bores, or carrying out the sectional compression fracture on the wall of the horizontal casing. In the embodiment of the invention, because the horizontal section is provided with the casing, a well wall support can be formed, and the well bore is not easy to be blocked due to carrying out various production increasing processes when the horizontal-section well bore is collapsed; in addition, the embodiment of the invention further can achieve the re-mounting and circular cleaning of the horizontal well bore so as to effectively increase the gas production rate of the coalbed gas well.

Description

technical field [0001] The invention relates to the field of coal bed gas exploitation, and more specifically relates to a method for increasing production of coal bed gas. Background technique [0002] The exploitation of coalbed methane has successively gone through vertical well mode, horizontal well mode and multi-branch horizontal well mode. Its purpose is to increase the leakage area of ​​the reservoir; the completion methods of CBM wells include cave completion and fracturing completion, which are often used in vertical wells, in addition to open hole completion for horizontal wells. The purpose is to increase the pores of the reservoir to increase the seepage capacity of the reservoir, so as to achieve the purpose of mining or increasing production capacity. [0003] Open hole completion means that after a well is drilled, no casing is run in to seal and isolate the well, and the well is directly completed and enters the drainage process. [0004] Fracturing refers...

AI Technical Summary

Problems solved by technology

[0006] However, due to the instability of the coal seam structure, if a branch wellbore is drilled in the wellbore in the horizontal section, during the drilling of the branch wellbore or in the subsequent CBM extraction process, the horizontal section wellbore may appear Collapse, so that the wellbore in the horizontal section is blocked, thereby affecting the production of coalbed methane

[0007] In addition, if the stimulation plan of fracturing is adopted in the wellbore of the horizontal section, due to the loose geological structure of the coal seam, the coal seam is easy to collapse under the condition of external force, and when fracturing is implemented, the gap between the packer and the bottom It cannot form an effective seal, which not only affects the effect of fracturing, but also easily causes the collapse of the coal seam in the wellbore

[0008] To sum up, in the existing technology, if the wellbore in the horizontal section implements subsequent production stimulation, it cannot effectively avoid the collapse caused by the unstable geological structure of the coal seam, thus affecting the effect of CBM production stimulation

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