ESP: 2017 #19

ESPs have many testing options. In this problem, we are given:

1) SG of the working fluid (10% water SG 1.01, 90% oil SPI 40)
...so SG = 0.1(1.01) + 0.9(0.8244) = 0.84

2) Net Lift 3,500 ft, Friction 300 ft, Surface pressure 200 ft
...so TDH = 3,500 + 300 + 200 = 4,000 ft

3) ESP with head capacity 4,000 ft/100 stages and 1 BHP/stage:
...4,000 ft / (4000 ft/100 stages) = 100 stages
...so BHP = (1 BHP/stage)100 stages(0.84) = 84 BHP

Fairly simple. If you aren't familiar with all three steps before seeing the problem it's hard to do it quickly. So be familiar with all three steps.