Study On The Design Of Quantitative Drainage For CBM

The reasonable producing measure is the key to develop coalbed methane efficiently and increase gas well production capacity.Based on the domestic and foreign literatures on the drainage system of CBM wells,this paper discusses the gas reservoir characteristics occurrence in Hancheng Block,migration and production mechanism and analyses the reasonable drainage system of CBM wells.By combining the field data analysis,theoretical research and experimental simulation.The permeability of coal seams is an important parameter of exploiting CBM.Based on the influence mechanism of the three geological effects on coal seam permeability,this paper analyses the influence of drainage on the coal reservoir permeability,establishes a mathematical prediction model and researches the rules of permeability changes in the process of CBM.According to analyzing the effect and the characteristics of CBM wells,this paper optimizes daily water production and pressure reduction range by using of the numerical simulation software of CBM.The key of drainage system setting must fully balance the relationship between fluid supply capacity of coal seam and pressure reduction drainage rate.The reasonable drainage intensity must fully balance the relationship between fluid supply capacity of coal seam and pressure reduction drainage rate.Based on combing the optimized goal of reasonable drainage intensity with considering the dynamic change of the permeability of CBM in production process,this paper proposes a method to determining reasonable drainage system in different production stages.Finally,application analysis is done by combined the WL1 well storage layer geological parameters with the production dates,which enhance understanding on coal seam gas discharge production and has reference significance on the production of CBM wells in Hancheng Block...