Discharge and mining method for coal-seam gas horizontal well of low-permeability coal reservoir

Abstract

The invention belongs to the technical field of coal-seam gas discharge and mining and provides a discharge and mining method for a coal-seam gas horizontal well of a low-permeability coal reservoir.The discharge and mining method for the coal-seam gas horizontal well of the low-permeability coal reservoir is used for solving the problems of the unstable yield, the poor gas producing effect and the like, caused by inappropriate discharge and mining strength, of a horizontal well discharge and mining system in the prior art. Aiming at a large-dip-angle coal seam, the highest position of a coalseam section of the horizontal well is used as a key control point of discharge and mining, and a quantitative discharge and mining system is made according to different discharge and mining stages of the horizontal well of the low-permeability coal seam, wherein the discharge and mining stages of the horizontal well of the low-permeability coal seam comprise the saturated water unidirectional flow stage, the unsaturated water unidirectional flow stage and the gas-water two-phase flow stabilizing stage. By utilizing the discharge and mining method, it can be guaranteed that the coal-seam gaswell can be depressurized and desorbed stably, large-area exposing of the coal seam due to excessively-fast lowering of the liquid level is prevented, meanwhile, a method is provided for selecting ofthe well repair time, and the adverse influences brought by well repair are avoided as much as possible.

Description

technical field [0001] The invention belongs to the technical field of coal bed methane extraction and particularly relates to a method for extraction of coal bed methane horizontal wells in low-permeability coal reservoirs. Background technique [0002] In addition to various objective conditions such as the complex structure of coalbed methane reservoirs and low reservoir permeability in my country, unreasonable drainage intensity is a decisive factor affecting the production of coalbed methane. As a low-permeability sensitive reservoir, the coal reservoir in the drainage project is affected by the effective stress effect, the matrix shrinkage effect and the Klinger effect at the same time, and its permeability is in a dynamic change. At the same time, the drainage intensity also needs to be adjusted accordingly. adjustment and optimization. [0003] Horizontal wells have become the main development trend of coalbed methane mining technology, but the current drainage syst...

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Problems solved by technology

[0004] Shanxi Jincheng Anthracite Mining Group Co., Ltd. State Key Laboratory of Co-mining Coal and Coalbed Methane aims at the problems of unstable output and poor gas production effect caused by improper drainage intensity in the current horizontal well drainage system, and then provides a Drainage method of coalbed methane horizontal well in low permeability coal reservoir

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