煤层气井有杆泵设备泵阀运动规律和开启条件

The kinetic characteristic and opening condition of fixed valve for sucker rod pump in CBM wells

在分析固定阀开启压差的基础上,建立了泵阀运动规律的数学模型和开启条件的计算模型,并利用仿真分析,获得泵阀在不同工况下的运动规律、水力损失和临界沉没度。结果表明:临界沉没度的存在可很好地解释低沉没度下泵阀不能顺利开启和井口间歇式出水现象;冲程和冲次的增大,使阀球升程增加,利于井液入泵;同时使速度变化加快,提高井液流速和携煤粉能力,但容易造成阀球"抖动"现象,降低泵效;固定阀阀球在开启瞬间的加速度和水力损失较大,二者幅值波动的频率较快并在短时间内迅速变小,最后趋向稳定;临界沉没度和水力损失随泵型和冲次的增加而增大,依据水力损失最大值可得到38 mm和44 mm泵的临界沉没度通常在3～5 m。

The mathematic models of kinematic law and opening condition were developed based on the opening pressure drop of fixed valve.The kinematic relation,hydraulic loss and critical submergence depth of fixed valve under different working condition were obtained with the realistic model.The results show that the critical submergence depth in the wellbore can reveal the phenomenon of the valve shutting down and intermittent water flow at the wellhead.An increased stroke and pumping speed results to an increased displacement of the valve ball and variation of initial velocity.And it is beneficial for the well liquid to go into the valve,enhances the ability to carrying coal dust,and makes the valve tremble and decline the pump efficiency.The instantaneous acceleration and hydraulic loss of the fixed valve are large,the frequencies of oscillation are high,and become low during the stroke.The critical submergence depth and hydraulic loss increase due to the size of pump and pumping speed.And based on the maximum hydraulic loss,the critical submergence depth can be obtained within 3～5 m for the pump of 38 mm and 44 mm.