METHOD FOR EVALUATING THE POWER OUTPUT OF A DRILLING MOTOR UNDER DOWNHOLE CONDITIONS

摘要

A procedure is described for determining the power output of a downhole drilling motor, when the motor is inside the wellbore. The technique uses stand-pipe pressur e and fluid flow rate as the main inputs. The power output of the motor is calculated by carrying out two low flow stall tests at flow rates lower than the drilling flow rate. These test s result in "off bottom" and stall pressures at the two flow rates. Another off bottom pressure is taken at the actual flow rate that will be used during drilling operations. From the use of the off bottom and stall pressure measurements, a determination is made of the differential pressure across the motor and the stall pressure at the actual drilling fluid flow rate. A full power curv e and a predicted operating stand-pipe pressure for optimal power generation are provided base d on an experimentally verified assumption regarding the change in rotation rate of the motor versus the differential pressure across the motor power section.