Frac: 2005 #59 (similar)

Fracture treatments are simple hydraulics, but there are a million ways to mess it up. The Guidebook has a single frac page, 7 PRD 2, in an attempt to keep it simple.

Getting a frac gradient from instant or initial shut-in pressure (ISIP) is a common calculation:



In the GB example above, ISIP is 1,800 psi, depth is 10,000 ft, and MW = 10 ppg. Hydrostatic pressure becomes 5,200 psi, and bottom hole frac pressure = 1,800 + 5,200 = 7,000 psi.

Frac gradient: 7,000 psi / 10,000 ft = 0.7 psi/ft

Frac problems are word problem heaven for test writers. Make sure you understand what's happening with both SI and dynamic pressures, and read the "hints" section in the Guidebook.