THE PERMEABILITY OF OIL-BEARING STRATA 375 



The obtained curve Q =f{K) should be considered from the point 

 of view of the possibility of using it to evaluate the permeability from the 

 specific resistance, since there can be cases when, due to the wide scatter 

 of the points or the small inclination of the curve Q =f{K), it cannot 

 be used to evaluate the permeability from the specific resistance with accept- 

 able accuracy. On the basis of what has been said above, we conclude that 

 the determination of the permeability of the stratum from its specific resistance 

 in any single bore-hole is undesirable for the following reasons: 



(a) A preHminary curve for the dependence Q =f{K) is necessary 

 and can only be obtained if, after the appropriate treatment there is sufficient 

 material on the permeability of the stratum for individual bore -holes. 



(b) The results may contain considerable errors, due to the incorrect 

 calculation of the coefficient for the increase in resistance (errors in the 

 determination of the specific resistance of the stratum and the stratum 

 water, the evaluation of porosity of the stratum and the relative resistance), 

 as well as errors connected with the influence of the water -petroleum contact. 



There is a probability of a considerable increase in the number of incorrect 

 conclusions for individual bore-holes, (at the present time, generally speaking, 

 comparatively small) due to a large error in the results for determining 

 permeability. It is apparent, however, that in the interpretation of material 

 for geophysical studies of single wells, it is useful to compare the obtained 

 value of the coefficient of the increase in resistance with its values for the 

 wells where the permeability of the stratum is known and to consider it 

 in the interpretation. 



The method of evaluating permeability from the specific resistance is 

 applicable in determining the mean value of permeability for the whole 

 stratum. 



The above conclusions are based on a comparison of data obtained from 

 the material of geophysical investigations of wells with the results of core 

 analysis. Opinion exists that derived comparison of the results for the 

 determinations of the reservoir properties of the strata obtained in the 

 covirse of geophysical studies, with the data of core analysis are not convincing 

 and do not make it possible to define the accuracy of the determinations 

 of reservoir properties of the strata from geophysical results, since cores 

 do not characterize a stratum as a whole, and their properties can differ 

 considerably from those of the stratum. 



In actual fact, the accuracy of the determination of the reservoir properties 

 of the strata from measurements on samples is relatively high and even 

 with a small number of cores from the stratum they give a more accurate 

 idea of the properties of the stratum than geophysical data. Furthermore, 



