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



Table 2 shows the mean and mean square errors for the separate determina- 

 tions of permeabiHty from the specific resistance by means of the MoROZOV 

 curves. These errors were calculated by the already mentioned method from 

 formulae (6) and (7). 



It can be seen that the use of the relationship between the coefficient for 

 increase in resistance and the reservoir properties as proposed by Morozov, 

 means that in some cases (for example, the D^^ and D^^ strata of the Romash- 

 kinsldan deposit) the error in the results decreases, in the other cases (for 

 example, the Z)j, Djj strata of the Tuimazinsldan deposit) it increases in 

 comparison with that observed in determining permeability by the Dohna 

 curve. The Morozov curves do not give favourable results, the error in 

 deterinining permeability by the specific resistance being rather large. 



Considering the curve suggested by Morozov Q =f{Kp^^^j^), we find 

 that they are obtained on the assumption that the interstitial water saturation 

 and consequently the coefficient of increase in resistance depend not only 

 on the permeabiHty of the rock, but also on their porosity, depending 

 to a much greater extent on porosity than on permeability. 



In fact, the Morozov curves Q "^fiKp^^^^) are represented approximately 

 by the formula 



Q-'-^-^lr (10) 



It follows that the relative change in the coefficient of increase in resistance 



- — is connected with the relative changes in permeability dK jK and 



dm 



porosity in the following way (neglecting the sign of the error) : 



m 



^^2^ + 10^. (11) 



Q Kper m 



Any relative change in porosity causes a 5 times greater change in the 

 coefficient of increase in resistance than the same relative change in permea- 

 bility. Therefore, despite the comparatively large changes in permeability, 

 the porosity will have a much greater effect on the coefficient of increase 

 in resistance, than the permeability. 



Thus, if the curves proposed by Morozov are correct then in view of 

 the large effect of porosity and the impossibility of an exact allowance for 

 its effect, we would still be unable to obtain from the specific resistance 

 sufficiently accurate values of permeability. 



The unusually high power -index of porosity and the shape of the curves 



