The following well conditions are given. Well depth, ft Drillpipe OD, in. 15,000 5 Ibm/ft in. effective ID 19.5 4.33 Drill collars (8-in.-ODX3-in.-ID), ft Casing (J-55) set at 4,500 ft, in. 600 10.75 40.5 Ibm/ft Bit diameter, in. (assume average hole size of 10 in.) Nozzles (three), in. Surface equipment Double-acting duplex pump, hp Liner, in. Stroke, in. Rods, in. Overall efficiency, % Maximum surface pressure, psi Surface piping equivalent to 200 ft of drillpipe Mud properties Density, Ibm/gal Rotational speed 3 6 100 | 200 | 300 600 Reading Minimum annular velocity, ft/min 9.875 1%2 1,500 6.5 18 2.5 85 3,500 12 1.8|3 10 15 20 36 120 a. Compute the equivalent circuiating density at depths of 4,000, 14,000, and 15,000 ft correspond- ing to an annular velocity opposite the drillpipe of 120 ft/min using the Bingham plastic model. Answer: 12.10 lbm/gal; 12.10 lbm/gal; 12.13 Ibm/gal. b. Compute the total nozzle area of the bit need- ed for maximum bit horsepower. Answer: 0.324 sq in.