Experimental Study Of CBM Horizontal Well Pulverized Coal Migration Characteristics

Coal seam with low tensile strength,compressive strength,elastic modulus and high poisson’s ratio.Coalbed methane Wells due to the pressure fluctuation in the process of drilling,mining,gas and liquid scour,mechanical collision,such as external force,will inevitably produce pulverized coal,pulverized coal output of coal-bed methane mining have advantageous one side,the right amount of pulverized coal,can dredge fluid migration channel,is advantageous to the fluid conductivity of coal seam,expand the scope of the pressure drop,increase CBM gas area,improve the gas production rate of coalbed methane Wells.But when the pulverized coal output is too large,can produce adverse effect.On the one hand,the pressure fluctuations or drainage intensity leads to pulverized coal,pulverized coal with liquid or gas phase migration.When the velocity of lower or meet can’t through the narrow gap,pulverized coal sedimentation deposition in the department,will reduce the original crack and support the conduction ability,resulting in a decline in reservoir permeability,on the other hand,as a result of horizontal well in drilling is a slight fluctuation type,and the liquid phase of the pulverized coal into horizontal section when migration to the uplink interval,if liquid velocity is not enough to carry up pulverized coal,pulverized coal and gradually fill in the wellbore.Cause different degree of blocking the wellbore,may cause the horizontal scrap.Migration to drainage pump position of pulverized coal,could lead to the phenomenon of submerged pump.Coal powder clogging pump suction,lax,the Jules verne is closed sharply decrease the pump efficiency.Sometimes forming sticky glue into the pump,the pump barrel and plunger wear and pump efficiency is reduced,or even stuck pump phenomenon,lead to high rank frequently during the process of examining the pumps.Pulverized coal is necessary to determine the starting conditions and rules,provide the basis for control the speed of high rank,and thus prevent submerged pump,such as stuck pump mining accidents,extension of pump overhaul period.Through simulation sample cuttings and movement in horizontal well sand samples get the following understanding:Start the migration regularity of different particle size of pulverized coal cuttings are basically the same.Relative migration regularity of sand sample is more complicated.But these two kinds of coal sample with the increase of liquid flow rate,follow a stationary-sliding-rolling-layer move-suspended state of migration.Compared with drilling cuttings sample size is small,migration needs smaller values of the flow of sand samples,this is because the sand sample good psephicity,easy to roll.Particle size is bigger,because the sand grains in sand sample density is big,drilling cuttings sheet for a better start.Simulation of the piping elevation Angle,then start the flow will change accordingly.Pulverized coal with dip under the pipeline,start the flow decreases,the elevation Angle,the greater the start,the more difficult.Under the oblique Angle of pipeline is determined,as the particle size increases,the start of the pulverized coal flow rate increased.To start using a function relationship between the flow and pulverized coal particle size fitting,fitting degree is higher.A function to start the relationship between flow rate and elevation fitting is very good also,it shows that in a single function can better predict different particle sizes and pipe under the elevation of pulverized coal flow.Pulverized coal in simulated duct change with external conditions and show the motion state of the main sliding,rolling,layer move,suspended.Gas phase after joining,interaction for three-phase medium state in pipeline gas relative flow disturbance effect is very strong,pulverized coal is easy to start migration is suspended with flow.Pipeline once Angle,gas liquid ratio,the greater the disturbance effect of the gas phase has the stronger,the migration efficiency of pulverized coal increases.Is directly related to the flow and pressure before and after the pipeline,the greater the pressure difference,the greater the flow,the relationship between using a function fitting degree is high.Finally established the liquid-solid two phase flow in the study of pulverized coal,gas liquid solid three phase flow start-migration model,can predict about different particle size of pulverized coal in a particular horizontal well under the elevation of starting flow,and different gas and liquid ratio corresponding differential pressure.