SUPPRESSING THE EFFECTS OF SWABING AND PISTONING ON THE DRILL ENGINE

摘要

A method of mitigating undesired pressure variations can include flowing fluid between wellbore sections, thereby mitigating a pressure differential due to drill string movement, and the fluid flowing between the wellbore sections via a bypass passage extending through a drilling motor. A drill string can include a drilling motor, a bypass passage in the drilling motor, a sensor, and a flow control device configured to selectively increase and decrease fluid communication between opposite ends of the drilling motor via the bypass passage, in response to an output of the sensor indicative of drill string movement. A method of mitigating undesired pressure variations in a wellbore due to drill string movement can include selectively preventing and permitting fluid communication between wellbore sections on opposite sides of a drilling motor, the fluid communication being permitted in response to detecting a threshold drill string movement.