Resource Evaluation Of Closed Gob CBM(Coalbed Methane) In Hegang And Jixi Mining Area

This thesis summaries the basic theroies of gob coalbed methane(CBM)by analysising of literature datas and job-site survey.Relizes that the material basis of CBM in gob is mainly the residual coal of mining layer and the adjacent coal seams in the mining influence area.The top boundary of the fracture zone is regarded as the vertical boundary of the gob CBM storage space,and the lateral boundary is calculated by using the angle of relief.The distribution of the internal fracture and permeability of the storage space presents the characteristics of O type circle,that is,the fracture and permeability value in the surrounding area of gob is higher than that in the medium area because of co MPaction.The migration of coalbed methane in gob is different at different stages,In the process of coal mining,the CBM from the coal seam and the adjacent layers migrates to the gob under the influence of the concentration and pressure,and some of them is taken away by ventilation,and some of them is gathered in the deep part of the goaf.When the gob is closed,the CBM mainly rises and moves along the high permeability channel,and collects to the top of the storage space.The preservation of CBM in gob is mainly affected by the development of fracture,the degree of water accumulation,and the sealing time,in view of the above,the gob is divided into three types,they are the airtight gob without water or little water,the opening gob and the gob sealed for long time,which the first is the best one.Thesis has put forward 6 principles for the division of the gob in the research area,and 19 resource predictable areas are divided.According to the gobs in the resource predictable areas whether connected,The 19 resource prediction areas are divided into 21 evaluation units.After analyzing and co MParing the calculation methods of the gob CBM,the resource constitute method is used to calculate the theoretical resources of all evaluation units,It shows that total resource is 7976.17×104m~3,There are 19 evaluation units in Jixi mining area,the resource is 5966.83×104m~3,and Hegang ming area has 2 evaluation units which the sum resource reaches 2009.34×104m~3.There are 5 evaluation units whose resource above 700×104m~3,accounting for 64.06% of the total resources,play a leading role in the total resource.This shows that the gob CBM has a highly concentrate degree,which is favorable for exploration and development.Based on the 3 indicators of resource potential,preservation condition and engineering condition,this thesis establishes a evaluation system.Finally,21 evaluation units are evaluated,The result shows that there are 11 excellent evaluation units,3 good evaluation units,2 middle rank evaluation units and 5 poor evaluation units.The evaluation system provides an important guidance for engineering.