| Coal seam gas drainage is an important measure to govern mine gas,however,mainstream study consider effective drainage radius as eference for drainage arrangement without taking drainage superposition and cracks’extension into account;In academic research and field application,the influence of different positions drainage bores in coal seam exist different extraction time is not considered,which is easy to cause a certain amount of resources waste or uneven gas drainage,and other adverse conditions.In addition,many studies have not established the multi-physical field coupling model of gas migration under the influence of stress field and seepage field.Conduct study by taking optimization of 3~#coal seam’s gas extraction in Luan Sima mine as the research goal,the basic gas parameters of 3~#coal seam were determined;Considering the fact that the pressure change of coal seam、the change of gas pressure and the adsorption and desorption of gas will have an important influence on the permeability and porosity of coal seam,this paper deduced the dynamic expression of the permeability and porosity of the coal seam,then established multi-physical field coupling numerical model of gas migration under the influence of stress field and seepage field;Using COMSOL Multiphysics to simulate for getting the influence law of different drainage bores diameter、drainage suction pressure and drainage time on the effect of gas drainage,then put forward the concept of"effective distance between bores"combining with the requirements of coal mine gas drainage and simulate to obtain the effective distance between bores under different drainage arrangement.Get a mixed arrangement of gas drainage scheme based on effective distance between bores by taking the fact that drainage holes in different positions exist different drainage time into account,combinined the advance situation of 1207working face in sima mine.Finally,the field industrial test and benefit evaluation analysis were carried out. |
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