Experimental Study Of The Pulverized Coal Particle Migration In Hydraulic Fracture In East Yunnan & West Guizhou Region

There is a large amount of resource and great development potential for coalbed methane in China.During the development of coalbed methane,the problem of pulverized coal production and migration will inevitably be encountered.Understanding of pulverized coal particles migration law in support cracks will be conducive to control the pulverized coal output and make a reasonable drainage system.Based on a comprehensive survey of the relevant research results at home and abroad,the following three aspects of the pulverized coal movement in the support cracks are studied.(1)Based on the analysis of the force of pulverized coal particles,the effect of the viscous force between the pulverized coal particles and the particles arrangement,the critical starting velocity model of pulverized coal particles is derived.Based on the capillary model,the fracture permeability model after filling pulverized coal is derived,based on the permeability model,the effect of different particle size ratio and filling rate on fracture permeability is obtained.(2)Based on the two-dimensional visual physical sand filling model experimental device.Through extensive investigation of the coal powder output in the drainage stage,data on the particle size of the proppant and the discharge of the pulverized coal,etc.And carry out the pulverized coal particles transport experiments in the cracks.The effects of pulverized coal particle size,coal powder mass fraction,proppant particle size and fluid velocity on the discharge of pulverized coal were obtained.The particle size distribution of pulverized coal at different velocity is obtained by using the particle size analyzer.At the same time,the damage degree of the permeability under different velocity is measured.(3)According to the variation of fracture permeability with velocity under different proppant particle size,combined with the pulverized coal particles starting velocity formula,the particle size of starting pulverized coal is determined when the maximum fracture permeability is reached.Based on the mechanics theory,the proppant shape variable under different closed pressure is obtained.And the formation water displacement is designed based on the formation and well fracturing parameters of a well in East Yunnan & West Guizhou region.