井筒内煤粉对单相流煤层气井井底流压的影响

根据煤层气井井底流压的分段计算方法,考虑井筒内煤粉含量和流体流动对井底流压的影响,建立了上行气固两相压差模型和下行液固两相压差模型,给出了考虑井筒内煤粉和流体流动的井底压力计算方法,并分析了井筒内煤粉对井底压力的影响,结果表明:井筒内煤粉对煤层气井井底压力的影响不可忽略。通过实例分析,当井筒内煤粉含量为3%时,由煤粉和流体流动引起的压差最大为0.147MPa,平均压差为0.13MPa。根据实测的井底流压通过该计算方法可以反求井筒内煤粉的含量,即根据井底压力的变化可以监测井筒内煤粉浓度的变化;依据煤粉排出量,可以得到未排出煤粉的量,进而估算未排出而沉积井底的煤粉量,得到埋泵所需时间,为修井作业提供参考。

Impact of pulverized coal in shaft on bottom-hole flowing pressure in single-phase coalbed methane well

Based on the subsection calculating method for bottom-hole flowing pressures in CBM well and considering the impact of pulverized coal content in shaft and fluid flow on bottom-hole flowing pressure,the paper has respectively established the two-phase pressure difference models of upcast gas-solid and downcast liquid-solid and given the calculating method for bottom-hole pressure with pulverized coal in shaft and fluid flow,and then analyzed the impact of pulverized coal on bottom-hole pressure in CBM well.The result shows that the impact of pulverized coal can not be ignored.Through analysis of the case,the biggest pressure difference caused by 3% coal powder and fluid flow is 0.147MPa,and the average differential pressure is 0.13MPa.With the measured data of the bottom-hole flowing pressure,the content of coal powder in shaft can be figured out through this method.According to the discharge amount of pulverized coal,the undischarge can be worked out and the deposited coal powder also can be calculated,which can help estimate the time needed to bury pump and provide reference for repairing well.