摘要
Pressure relief to increase permeability significantly improves gas extraction efficiency from coal seams.In this paper we report results from simulations using FLAC 3D code to analyze changes in coal displacement and stress after special drill slots were formed.We investigated the mechanism of pressure relief and permeability increase in a high-gas and low-permeability coal seam through the modeling of gas flow.This allows the development of the technology.Slotting across rock layers in the coal seam with a rotary type cutter was then applied in the field.The results show that pressure relief and permeability increases from slotting the coal seam can increase the transport and the fracture of the coal.This expands the range of pressure relief from the drilling and increases the exposed area of the seam.The total quantity of gas extracted from slotted bore holes was three times that seen with ordinary drilling.The concentration of gas extracted from the slotted drills was from two to three times that seen using ordinary drills.The gas flow was stable at 80%.Improved permeability and more efficient gas extraction are the result of the slotting.The roadway development rate is increased by 30-50% after gas drainage.This technology diminishes the lag between longwall production and roadway development and effectively prevents coal and gas outburst,which offers the prospect of broad application.
Pressure relief to increase permeability significantly improves gas extraction efficiency from coal seams. In this paper we report results from simulations using FLAC3D code to analyze changes in coal displace- ment and stress after special drill slots were formed. We investigated the mechanism of pressure relief and permeability increase in a high-gas and low-permeability coal seam through the modeling of gas flow. This allows the development of the technology. Slotting across rock layers in the coal seam with a rotary type cutter was then applied in the field. The results show that pressure relief and permeability increases from slotting the coal seam can increase the transport and the fracture of the coal. This expands the range of pressure relief from the drilling and increases the exposed area of the seam. The total quan- tity of gas extracted from slotted bore holes was three times that seen with ordinary drilling. The concen- tration of gas extracted from the slotted drills was from two to three times that seen using ordinary drills. The gas flow was stable at 80%. Improved permeability and more efficient gas extraction are the result of the slotting. The roadway development rate is increased by 30-50% after gas drainage. This technology diminishes the lag between longwall production and roadway development and effectively prevents coal and gas outburst, which offers the Drosnect of broad anDlication.
基金
supports provided by the National Key Basic Research and Development Program (No.2011CB201205)
the National Natural Science Foundation of China (No.50534090)
the Independent Research of State Key Laboratory of Coal Resources and Mine Safety(No.SKLCRSM08X03)
the State Key Laboratory of Coal Resources and Mine Safety of Research Foundation of China University of Mining & Technology (No.09KF09)
the National Natural Science Foundation of Youth Science Foundation (No.50804048)
the Project Funded by the Priority Academic Program Development of Jiangsu Higher Education Institutions (CXZZ12_0958)
