Page 151 - Standard Handbook Petroleum Natural Gas Engineering VOLUME2
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120 Reservoir Engineering
0 5 10 15 20 25 30 35 40
m, Porosity (pu)
Figure 5-65. Schlumberger chart (after Wyllie and Rose) for estimating
permeability [199].
I
R, = O.69(Rmf) - (5-89)
where Km = 0.847 for 10 lb/gal
0.708 11 lb/gal
0.584 12 lb/gal
0.488 13 lb/gal
0.412 14 lb/gal
0.380 16 lb/gal
0.350 18 lb/gal
These relationships work well for most muds (except lignosulfonate) with
resistivities between 0.1 a-m and 10 a-m.
Another approximation that works well for salt muds is:
Rm, = 0.75Rm (5-90)
Rmf = 1.5Rm (5-91)
Temperature Relationships. Mud resistivity is a function of temperature and
ion concentration. Since temperature increases with depth due to geothermal
gradient, the mud resistivity is lower at the bottom of the hole than at the
surface (pits). The temperature of a formation can be found with an equation
suggested by Hilchie [200]:
