| A moderate and high efficient transportation of coal particles in coal-bed methane(CBM)wells is important to the development of CBM production system which can improve and stablize the CBM production.As a result,it’s nessessary to fully understand the transport rules of coal particles in horizontal wellbores.Based on a full-scale gas/liquid/solid three-phase flow experimental apparatus,water-carrying and gas&water-carrying coal particles experiments are carried out,of which the basic experiment parameters are according to gas and water production,coal particle physical properties and the coal particle mass concentration in various Chinese CBM fileds.Firstly,the transport mechanisms of coal particles both carried by water and gas&water in horizontal CBM wellbore are investigated and how the coal particle and coal particle dune migrate are detailedly described in this paper.Secondly,the effects of particle diameter,particle concentration,gas flow rate and water flow rate on the height of coal particle bed in horizontal wellbore are investagated and discussed.In this research,because of existence of coal particles bed in horizontal wellbore,a new definition of superficial velocity of fluid called real superficial velocity is presented and based on the real superficial velocity,the flow pattern map in gas&water-carrying coal particle experiment is acquired.A comparison between the flow pattern map and Mandhane flow pattern map shows that those flow pattern data points are always near the transition lines either between smooth stratified flow and slug flow or between wavy stratified flow and smooth stratified flow when the height of coal particle bed keeps steady dynamically.A new three-dimensional flow pattern map is presented using three nondimensional numbers deduced by ?-theorem.Dimension analysis and experiment data were combined to develop a model for predicting the height of coal particle bed which has practicle and theoretical meaning to the CBM production. |
PDF Full Text Request