QUESTION 3

Determine the pressure at the bottom of the drill collars if the frictional loss in the drillstring is 900 psi, the flow rate is 350 gal/min, the mud density is 10 ppg and the well depth is 8,000 ft. The internal diameter of the drill collars is 2.75 in. and the pressure developed by the pump is 2,600 psi.