Patent attributes
A control system that corrects differential pressure measurements with downhole annulus pressure information is disclosed. When differential pressure is zeroed with the BHA off-bottom, the annulus pressure value is baselined. During drilling, a controller receives surface differential pressure measurements and annulus pressure measurements. As the controller receives each new annulus pressure measurement, it compares it to the baseline annulus pressure value to obtain a different annulus pressure value. The controller corrects the surface differential pressure measurements with the annulus pressure measurements. As the controller receives each new surface differential pressure measurement, it subtracts out the current difference annulus pressure value. As a result, the modified surface differential pressure measurement remains a reflection of mud motor performance that removes the influence of the increased density of the fluid, thereby improving autodrilling control. The modified surface differential pressure measurements are also used to determine mud motor torque.
