4.53 Calculate the surge pressure in a 7.875-in. hole below a 12,000-ft drillstring composed of 11,400 ft of 5-in. drillpipe (4.3-in. ID), 600 ft of 6.25-in. drill collars (2.75-in. ID) and a bit containing three 1%2-in. nozzles. The drillstring is being lowered through a 14-lbm/gal drilling fluid having a flow- behavior index of 0.8 and a consistency index of 250 eg cp at a maximum rate of 3.5 ft/s.