采用激光多普勒测速法可以测量钻井井筒环形空间(简称“环空”)的速度场。测量时,试验流体自下而上流经由井筒内、外管构成的环形空间。当激光穿过圆形管道时,由于柱面透镜效应,影响了速度场的准确测量。一般的解决办法是在圆形管道外围做一个透明的方水盒,以补偿柱面球差。方水盒 Laser Doppler velocimetry can measure the velocity field of the wellbore annulus (“annulus”). Measurement, the test fluid from bottom to up through the wellbore, the outer tube of the annular space. When the laser passes through a circular tube, the accurate measurement of the velocity field is affected due to the cylindrical lens effect. The general solution is to make a transparent square water box around the circular pipe to compensate for the cylinder spherical aberration. Square water box