Page 306 - Standard Handbook Petroleum Natural Gas Engineering VOLUME2

Fluid Movement in Waterflooded Reservoirs 273

4

3 .............. .

dfW
dSW

2 -.. ....

I

0
IO 20 30 40 50 60 70

sw , O/O
Figure 5-154. Change in fractional flow of water with change in water
saturation [133].
1
Qi =
(5-212)

Thus, the reciprocal of the slope of the tangent line gives the cumulative water
influx at the time of water breakthrough. When a value of Qi and the injection
rate are known, the time to reach that stage of the flood can be computed.