Problem 5

The physical characteristics of the 3-A-2

reservoir are described in figure to the

right:

a) Calculate the percentage of recovery,

assuming this reservoir could be

produced at a constant cumulative

gas oil ratio (GOR) of 1100 SCF/STB,

when the reservoir pressure falls to

3550, 2800, 2000, 1200 and 800 psia.

Plot the percentage recovery versus

reservoir pressure.

Formation volume factor, bbl/STB

1.65

1.60

1.55

1.50

1.45

1.40

1.35

1.30

800 1200 1600

rmation

oil ratio

acto

Deviation factor

2000 2400

2800

Pressure, psia

0.96

0.94

0.92

0.90

0.88

0.86

3200 3600 4000 4400

Gas deviation factor

1100

1000

900

700

600

500

400

300

Solution gas-oil ratio, SCF/STB/n6.2

Problem 5 (Continued)

b) Recalculate recoveries assuming the that cumulative produced GOR is 3300

SCF/STB, to demonstrate the effect of increased GOR on recovery. Plot the

percentage of recovery versus pressure on the same graph used in part (a).

c) How is the percentage of recovery affected, if the produced GOR is tripled?

d) Will shut-in of high GOR producers improve recovery in a reservoir? Explain.