374 S. G. KoMAROv and Z. I. Keivsar 



different permeabilities. The curves 1-3 are well -known curves of Jones^^', 

 the curves 4-9 were constructed by Masket (^^), the other curves were 

 taken from the work of Zaks(^). 



Fig. 10 shows the curves for the dependence of the residual water saturation 

 on the permeability, drawn from the curves for the dependence of the coeffi- 

 cient of increase in resistance on the permeabiUty. 



The curves are drawn from the data of Figs. 2 and 3 and the actual curves 



Q=fiKper) (Fig. 6). 



The value of thecoefficient of interstitial water saturation K^ ^ was 

 determined from the coefficient of increase in resistance Q from the formula 



For the curves 1 and 2 of Fig. 2 the interstitial water saturation was 

 determined from the curves proposed by Dakhnov and Dolina 



A comparison of the curves on Figs. 9 and 10 shows that the values 

 obtained when studying samples for the interstitial water saturation (Fig. 9) 

 differ considerably from the so-called empirical value of the interstitial 

 water saturation, with which we start in determining permeability from the 

 specific resistance (Fig. 10)*. 



Let us note that methods of determining the interstitial water saturation 

 lead to different results. The data for the interstitial water saturation obtained 

 by analysing cores, cannot be used to estabhsh the dependence of the coefficient 

 of increase in resistance on the permeabilityt. 



It follows from Fig, 10, that the residual water saturation for different rocks 

 has a different value. This is in full agreement with our conclusion reached 

 above that each stratum should have its own curve Q —f{K). The curves for 

 the dependence of the coefficient of increase in resistance on the permeability, 

 which are necessary to determine the permeability from the specific resistance, 

 should be constructed for each stratum from the results of comparing the 

 actual coefficient of increase in resistance with the values of permeabihty 

 obtained in the study of cores, as was done for example, in Fig. 5. Since 

 the connection between these values is insufficiently close, it is necessary 

 to have a sufficiently large number of results (large number of points), at 

 the same time bearing in mind the porosity of the strata. 



* An exception is provided by the experimental results of MoROZOV (8 on Fig. 10), 

 casting some doubt in this connection. 



+ Furthermore, in deducing from the interstitial water saturation the coefficient for 

 increase in resistance an extra error would be introduced which would lead to a decrease 

 in the accuracy of the curve Q = /{Kp^j). 



