The R Sand is a volumetric oil reservoir whose PVT properties are shown in Fig. 5.9. When the reservoir pressure dropped from an initial pressure of 2500 psia to an average pressure of 1600 psia, a total of 26.0 MM STB of oil had been produced. The cumulative GOR at 1600 psia was 954 SCF/STB, and the current GOR was 2250 SCF/STB. The average porosity for the field is 18% and average connate water 18%. No appreciable amount of water was produced, and standard conditions were 14.7 psia and 60°F.

a) Calculate the initial oil in place.

b) Calculate the SCF of evolved gas remaining in the reservoir at 1600 psia. 

c) Calculate the average gas saturation in the reservoir at 1600 psia.

d) Calculate the barrels of oil that would have been recovered at 1600 psia if all theproduced gas had been returned to the reservoir.

e) Calculate the two-phase volume factor at 1600 psia.

f) Assuming no free gas flow, calculate the recovery expected by depletion drive performance down to 2000 psia.

g) Calculate the initial SCF of free gas in the reservoir at 2500 psia.

 

1.30 1.26 1.26 575 0.87 % 550 1.24 FVF 0.86 2 525 SOLUTION GR GAS DEVIATION FACTOR 0.85 , 500 01.22 0.84 47 0.83 450 21.20 0.82 425 0.813 400 375 1500 1600 1700 1800 1900 2000 2100 2200 2300 2400 2500 PRESSURE, PSIA 350 Fig. 5.9. PVT data for the R Sand Reservoir at 150F. FORMATION VOLUME FACTOR, BBL/STB SOLUTION GOR, SCF/STB