Influence Of Pulverized Coal Blockage On Fracture Conductivity Of Coal And Rock

Coal beds in China are characterized by low permeability,low porosity and low saturation three.Therefore,the effective development layer of coal bed gas storage needs the aid of hydraulic fracturing measures,the purpose is forming a fracture or fracture network with high diversion capacity and increasing the drainage area of the bottom of the well as well as improving the production of coal bed gas.The conductivity of coal and rock cracks is an important parameter for predicting the capacity of coal bed gas.The coal reservoir has the characteristics of low porosity and permeability,low closure pressure,small elastic modulus,large Poisson's ratio,soft brittle and complicated fracture system.The fracture morphology of the coal seam is complicated,the coal seam is easily broken and the fracture pores are easily blocked.It is difficult for the fracture conductivity to be accurately evaluated.The coal is produced after the closed pressure.The existing model only takes into account the influence of the parameters of the proppant on the diversion energy,and does not take into account the different closure.The effect of pulverized coal blockage on diversion capacity under pressure needs to be set up to model the influence of pulverized coal blockage on diversion capacity and to evaluate and analyze the diversion capacity of pulverized coal jams to coal and rock cracks.At first this study analyze the physical and mechanical properties of the coal seam in the studied area,through the physical and mechanical characteristics of the coal and rock are obtained through the analysis of the physical and mechanical characteristics of the coal and rock.Coal bed is broken by closed pressure,and the process of coal powder injection fracture proppant filling layer in the process of coal seam gas drainage is simulated by the use of fracture conductivity meter and flow pump.The influence of different coal powder particle size and content on coal powder production can be influenced by the coal powder content,and the effect of coal powder quantity under different conditions is obtained.This study is based on the three-dimensional elastic mechanics and the space geometry theory and the proppant of diamond shaped hexahedron.Considering the particle size and the index of the content,the proppant will be deformed under the closed pressure,which leads to the reduction of the width of the crack,and the presence of coal will occupy the pore volume of the crack and reduce the porosity and permeability.The formula for calculating the conductivity of pulverized coal could be derived.The effect of coal powder particles and the content of coal powder on the conductivity of the proppant is simulated by the use of a flow pump and a flow pump in order to simulate the effect of coal powder particle size and the content on the conductivity.The experiment shows that the coal powder is easy to infill the filling layer of proppant,and it is not easy to discharge with water,and it also causes serious damage to the diversion ability.Agglomeration and adhesion of coal powder and bridge throat are the main reasons for the damage of coal powder to the fracture conductivity of coal and rock.The coal powder particles with smaller particle size are more easy to aggregate and be attached and have great influence on the diversion capacity.With the increase of coal powder concentration,the coal powder blockage has a stronger influence on the conductivity of coal bed crack.With the increase of coal powder concentration,the pulverized coal blockage has a great influence on the diversion capacity.