Page 294 - Standard Handbook Petroleum Natural Gas Engineering VOLUME2

Secondary Recovery 461

Volumetric calculations for gas injection are given in Table 5-34. The material
balance equation for dispersed gas injection in a solution-gasdrive reservoir
where there is no water influx, no water production, and no gas cap can be
expressed in terms of the oil produced during an interval [254]:

(5-201)

Table 5-34
Volumetric Calculations for Gas Injection
Gas drive field with gas cap
-
B So dR, + QoS0 dBo - (1 -So - S,) + m(i - S,) de,
L
dS.= Bo dP kOPsB0 cb B, dP
dP l+%
Qs
m = ratio of gas-cap pore volume to oil-zone pore volume, bblhbl or WM. For each 1
bbl of oil zone there will be m bbls gas cap.
Reinjection of all produced gas-pressure maintenance

BS
dR
RBS
dB
ZI-20- (l-So-S,)dB,
dS,
-= Bo dP B: dP B, dP
dP 1-=
BO
Gas reinjection
Producing GOR R = -
k,PoBo
koPgB, +Re

I = fraction of gas that is reinjected

m = ratio of aas-cao volume to oil-zone volume

From References 14 and 254.