Movement characteristics of coal powders at bottom of coalbed methane well under jet flow

The removal and discharge of coal powders from coalbed methane wellbore is the key to maintaining continuous production. For this reason, based on the submerged jet theory, the force and migration starting conditions of coal powder particles deposited at the bottom of the coalbed methane well are analyzed by analyzing the cohesiveness of coal powders, and a model for the starting and migration of coal powders at the bottom of the well under submerged jet conditions is established; Considering the adhesion between coal dust, the adhesion coefficient is used to characterize the adhesion between particles, a mechanical model of coal dust particles deposited at the bottom of the well is established, and the corresponding calculation formula for the outlet flow rate of the coal dust cleaning nozzle is derived. The fluid mechanics parameters of the bottom of the well coal dust cleaning under different conditions are obtained, and the numerical simulation method is used to simulate the whole process of jet flushing of the bottom of the well coal dust deposited, and the effect of the bottom of the well jet flushing of coal dust deposits is analyzed, providing a theoretical basis for the bottom of the well coal dust flushing process. Considering the bonding force between coal dust, characterize the bonding force between particles with the bonding force coefficient, establish a mechanical model for coal dust particles deposited at the bottom of the well, derive the nozzle outlet flow rate calculation formula for coal dust cleaning, and derive the hydromechanical parameters for coal dust cleaning at the bottom of the well under different conditions, and simulate the whole process of jet flushing coal dust deposited at the bottom of the well using numerical simulation methods, analyze the effect of the jet flushing coal dust deposits at the bottom of the well by the changes of the depth of the flushing pit and the width of the pit under different parameters, and provide a theoretical basis for the process of coalbed methane well bottom coal dust flushing. The effect of flushing coal dust deposit is analyzed by the change of flushing pit depth and pit width under different parameters, which provides theoretical basis for coalbed methane wellbore coal dust flushing process. image