STUDY ON THE DEFORMATION LAW AND MECHANISM OF WEAKLY CEMENTED GAS DRAINAGE UNDER ENVIRONMENTALLY DEVELOPMENT PRINCIPLES

摘要

In view of the current research status that the deformation behavior and mechanism of the reservoir during the development of weakly cemented argillaceous gas drainage are not completely clear,this paper firstly conducts a study on coal and rock samples drilled at four depths in Wuhushan Coal Mine of Wuhai Energy Limited Company,Inner Mongolia,based on triaxial mechanical characteristic experiments.After the mechanical performance test,it is found that the cohesion of the coal seam is lower than 1.3 MPa,which is a weakly cemented coal seam.At the same time,based on the experimentally obtained mechanical parameters of the reservoir,a numerical simulation study of the coal compaction and deformation behavior during the CBM development process was carried out.The results of the study found that: (1) CBM development is the key to reservoir deformation,and the compaction and deformation of the reservoir in the vicinity of the wellbore are particularly serious.(2) There are great differences in the deformation behavior of the reservoir at different depths.The subsidence of the upper boundary of the reservoir will continue to intensify with the continuous development of gas drainage,and the maximum subsidence will eventually reach 8.13cm.However,the lower boundary of the reservoir will have an "upward arch" phenomenon in the early stage of development,and gradually turn into subsidence after the CBM development operation lasts for 50 days and continue to intensify.The final maximum subsidence of the lower boundary of the reservoir is only 3.98cm.This study can provide reference and support for the avoidance of surface collapse during the development of gas drainage and the design and optimization of gas drainage development programs.