Drilling Horsepower: 2016 #63

A rig is expected to run at 100 RPM at 14,000 ft depth. What's a back-of-the-envelope estimate of the drilling horsepower required?

For this problem, use a Torque Factor Estimate and the equation F(RPM).
F=1.5 10,000 ft, light), F=1.75 (10,000 ft-15,000 ft, average), and F=2.0 (>15,000 ft, heavy)
Hence, 1.75(100) = 175 hp (A).

I have never seen this pre-drilling estimate in an SPE book (I first saw it in Mian, P288) but I like to use it for a quick check on any horsepower problem, so it's handy to know in real life or even an exam.