Page 215 - Standard Handbook Petroleum Natural Gas Engineering VOLUME2

184 Reservoir Engineering

According to Schiumberger [220] the log response may be described as:

Elog = E,( - $) + EW$'w + &y$(' - 'w) (5-118)

Solving for Sw:

(5-119)

Porosity ($) can be found either from an openhole porosity log or by com-
bining the ratio curve and Gag. Figures 5-108 to 5-111 are charts to find porosity,

Sandstone, 5 1/2 -in. Casing, 8-in. Borehole, Fresh Water Cement, Tool Eccentered

5

4

.-
0
w
2
3

1

QSchlumberger
0

Figure 5-108. Chart for determining porosity and apparent water salinity from
Zlog and ratio curves in 5 1/2-in. casing and an 8-in. borehole [199].