Page 325 - Standard Handbook Petroleum Natural Gas Engineering VOLUME2

292 Reservoir Engineering

I .o I I I I I I I I I

> 0.8

-
0.6
-
>.
t,
=1 -
m 0.4
a
w -
P
a
w -
a 0.2 WOR = 50
-

0
0 0.2 0.4 0.6 0.8 I .o
VOLUMETRIC SWEEP EFFICIENCY

Figure 5-169. Effect of permeability variation and mobility ratio on volumetric
sweep at WOR = 50 [307].

(text continucd jvm page 289)
Estimation of Waterflood Recovery by Material Balance

Oil recovered by waterflooding, Np+ in STB, can be estimated from [278]:

7,758Ah@[S, - E3S, - (1 - E,)S,]
N, = (5226)
Bo

where 7,758 is the number of barrels per acre-ft, A is areal extent of the
reservoir in acres, h is reservoir thickness in ft, $ is the fi-actional porosity, S
is the oil saturation at the start of waterflooding, S, is the waterflood residua
oil saturation, S, is the initial oil saturation, Bo is the oil formation volume
factor, and is the volumetric sweep or fraction of the reservoir volume swept
by the injected water when the economic limit has been reached. In terms of
the original oil in place, the waterflood recovery is [278]:

(5-227)