煤层气水平井井筒煤粉迁移规律试验研究

Experiment study on migration law of pulverized coal in borehole of coalbed methane horizontal well

为研究煤层气水平井井筒煤粉迁移特征及规律,有效控制煤粉产出,开展了多相流驱替状态下的水平圆管煤粉迁移物理模拟试验。通过调节流量、控制压差的方式,分析了不同粒径大小的煤粉在不同圆管倾角下的迁移特征及规律。结果表明：生产条件下井筒流态以紊流为主,应重点研究了雷诺数为4 000-6 000下的流态;两相流煤粉迁移模式为滑动、滚动、层移和悬移,三相流煤粉迁移主要受不同流型的影响;煤粉迁移模型表明煤粉迁移制约因素主要有流量、流型（气液比）、煤粉粒径、管道倾角和压差。综上认为,钻井阶段选择合适造斜点,控制井斜角变化;考虑煤粉性质及排采阶段变化,适时调整排水强度和井底压降,有效控制井筒流态,可保证井筒内煤粉适度产出。

In order to study the migration features and law of the pulverized coal in the well bore of the coalbed methane horizontal well and to effectively control the pulverized coal production,a physical simulation experiment of the pulverized coal migration in a horizontal pipe was conducted under the condition of the multi-phase flow displacement.With a method to adjust the flow and control the pressure difference,the paper analyzed the migration features and law of the different particle size pulverized coal under the inclination of the different round pipe.The results showed that under the production condition,the flow state in the well bore was turbulent flow mainly and the flow state of the large Reynolds number was under the range of 4 000 - 6 000.The migration mode of the two phase flow pulverized coal was sliding,rolling,layer movement and suspended movement and the migration of the three phase flow pulverized coal was mainly affected by the different flow mode.The pulverized coal migration model showed that the restricted factors of the pulverized coal migration mainly were the flow,flow mode（ gas and liquid ratio）,particle size of the pulverized coal,pipe inclination and pressure difference. The above could be considered that a suitable whipstocking point should be selected at the drilling period and the variation of the well inclined angle should be controlled.The consideration of the pulverized coal properties and the variation of the drainage stage,time adjustment of the water drainage strength and the pressure drop at the well bottom and effective control of the flow mode in the well bore could ensure a proper pulverized coal production in the well bore.