煤层气压裂返排过程中煤粉产出规律实验研究

煤层气压裂返排过程中产出的煤粉影响煤层气解吸运移，易造成煤层渗透率的永久伤害，降低气井产气量。采用自主研发的压裂液裂缝返排实验装置，模拟一定煤粉粒径配比关系下，采用不同的排采制度和不同外加液体，研究裂缝中煤粉的运移规律，测定煤粉和支撑剂被携带出的临界流量和煤粉返排效率，揭示煤粉运移与流体流速、外加液体关系的变化规律。研究表明：清水不能润湿煤粉，煤粉悬浮剂能较好润湿煤粉；煤粉含量越大，流出率越低；煤粉流出量随时间变化满足幂函数递减规律；变排量排采可以增大煤粉的返排效率。

Regularities of coal powder migration during fracturing liquid flowback in coalbed methane well

With the use of fracturing fluid flowback experiment apparatus developed independently, this paper is to study the coal powder migration regularities with different percentage of coal powder of various sizes and different drainage system, plus distinct fluids. We explored the critical flow rate for coal powder and proppant migration, as well as the coal powder flowback efficiency. We aimed at establishing the relationship among coal powder migration and fluid velocity and various fluids. Experiments show that water doesn't wet the coal powder, but coal powder suspending agent does. The more the coal powder is, the lower the discharge rate. The change of outflow volume of coal powder versus time meets the law of power function decreasing. Drainage with variable discharge rates can promote the flowback efficiency of coal powder.