Well Communication: 2017 #35

Problem 35. Your company investigates a lease sale containing two wells, A and B. Kelly bushing elevations are 1,000 ft and 0 ft above MSL, respectively, and bottom hole pressures of 3,170 and 3,500 psi, respectively. Both wells are 11,000 ft vertical depth to the perforations with pressure gradients of 0.3 psi per foot. The seller claims the two wells are in communication. Which of the following is most likely TRUE?
 
(A) The seller is incorrect; the wells are about 6 percent different in reservoir pressure and unlikely to be in communication.
(B) The seller is correct; the two wells are about 1 percent different in reservoir pressure and thus likely to be in communication.
(C) The seller is incorrect; the wells are over 10 percent different in reservoir pressure and unlikely to be in communication.
(D) The seller is correct; the two wells are about 4 percent different in reservoir pressure and thus likely to be in communication.

This problem is pretty straightforward and calculates to "B". But it requires practical but diverse petroleum engineering knowledge that trips many up.

Specifically: how much pressure difference is there within a reservoir from well to well? How to calculate pressures in wells that have different MSL depths? Nothing complex, just meat-and-potatoes for the average experienced engineer, but it can take time to think it through and look for possible tricks.

If you have more questions (or notice an error) note it in the comments below. For more help, this type of problem is in 13 RES 8 and SPE TS8 (where I got the idea for it). Myself, I'm used to drilling in the flats...for Rocky Mountain types this sort of problem is probably a yawn...