Question

You have been asked to review the performance of a combination
solution gas, gas-cap drive reservoir. Well test and log information show
that the reservoir initially had a gas cap half the size of the initial oil
volume. Initial reservoir pressure and solution gas-oil ratio were 2500 psia
and 721 SCF/STB, respectively. Using the volumetric approach,
initial oil in place was found to be 56 MM STB. As you proceed with the
analysis, you discover that your boss has not given you all the data you
need to make the analysis. The missing information is that at some point
in the life of the project a pressure maintenance program was initiated
using gas injection. The time of the gas injection and the total amount of
gas injected are not known. There was no active water drive or water
production. PVT and production data are in the following table:

a) At what point (i.e., pressure) did the pressure maintenance program
begin?

b) How much gas in SCF had been injected when the reservoir pressure is
500 psia? Assume that the reservoir gas and the injected gas have the
same compressibility factor.

Answer 1

I hope this will help you ?