Characteristics of pulverized coal with water of low rate in three-layer flow field of high-inclined pumps

Dynamic performance on the coal flow with water in three-layer field is essential for the reliability of pump and normal operation of horizontal and inclined wells.Model of three-layer flow field in high-inclined pump is set up based on the experimental results of water-coal two phase flow.The equations of continuous flow,momentum and diffusion and the mathematical model of water-coal two phase flow are developed under the coupling conditions of high inclination,low flow rate and low viscosity.Characteristics of pulverized coal with the water of low flow rate in three-layer flow field is analyzed through the numerical simulation and field test.It provides the basis for the design of high-inclined pumps and pumping systems and the measures of pumping stroke and speed and coal control in horizontal and inclined wells.The results show that the pressure gradients of suspension and moving layer are enhanced with the increases of pump inclination and coal density.The effect of pump inclination on pressure gradient is more obvious than that of coal density in three-layer flow field of high-inclined pumps.The increase of coal concentration leads to the improvement of pressure loss in suspension and moving layer and then the decrease in suspension layer The increased two-phase viscosity results in the increased pressure gradient in suspension and moving layer.The increase of flow rate leads to the inclined pressure loss in moving layer and the pressure loss decreases rapidly with high flow rate.Pressure losses in suspension layer decrease with the increased flow rate and then trend to be stable.Coal concentration near the entrance increases with the decreased velocity of the plunger during the motion of sucker rod.Moreover,the effect of velocity fluctuation on coal deposition in suspension layer is less obvious than that in other layers.