THE PERMEABILITY OF OIL-BEARING STRATA 359 



large, and as a consequence the water saturation of the stratum will not 

 correspond to its permeability. The method for determining permeability 

 by the specific resistance is therefore applicable only to a stratum (or part of 

 a stratum), which is much higher than the water-petroleum contact. 



MoROZov^^^) considers that the determination of permeabihty by the 

 specific resistance can be carried out for strata 16 m above the water-petro- 

 leum contact, since only then is the water saturation of the petroleum stra- 

 tum interstitial. This condition represents a very great limitation of the 

 method. 



Evidently, depending on the surface properties of the particles making 

 up the stratum, the properties of the stratvim water and petroleum this 

 distance will be different. According to Dolina^^' the possibility of deter- 

 mining the permeability from the specific resistance should be estabhshed 

 in each individual case, depending on the position of the water-petroleum 

 contact and the characteristics of the stratum. 



To establish the effect of the water-petroleum contact on the accuracy in 

 determining permeability from the specific resistance the above mentioned 

 determinations were made for strata at varying distances from the water- 

 petroleum contact. The results are given in Table 3. 



As follows from Table 3, there is no systematic reduction in permeabi- 

 lity and no large error in its determination at a small distance of the stratum 

 from the water-petroleum contact. This indicates that the effect of the 

 water-petroleum contact on the results of determining permeability is small. 



MoROZOV^^^) considers it possible to determine the permeability at 

 a distance of less than 16 m from the stratum to the water petroleum con - 

 tact. He recommends that the obtained values Kp^^ should be multiplied 

 by a correction coefficient 



" = !¥• <«> 



where h is the distance along the vertical from the middle of the studied 

 zone to the water -petroleum contact. 



However, the use of this correction is clearly undesirable for the following 

 reasons. 



1. It is insufficiently well established* and it is obviously faulty. The water 

 saturation of an oil-bearing stratum depends not only on its distance to the 

 water-petroleum interface, but also on a large number of other values : the 

 density of the petroleum and water, their capillary properties, the character 



* Morozov does not give the basis of the correction coefficient //. 



