E. A. POLYAKOV 



Fig. 2. A scheme of placing of probes in an electrolyte-containing tank in testing the 

 nature of the electric field. 



The resistivity-meter and many of its constituent parts are enclosed in 

 a metallic container. Furthermore, certain of the metallic parts are situated 

 in the immediate vicinity of the probe electrodes. As the specific resistance 

 of the drilling fluid alters, the ratio of the contact resistance of the metallic 

 parts to the resistance of the fluid changes as well, bringing about a re- 

 arrangement in the electric field of the probe, since with the decrease in the 

 salinity of the drilling fluid the intensity of the electric field grows in the 

 direction of the shortest distance from the metallic parts of the resistivity- 

 meter and vice versa. The rearrangement of the field leads to a change in 

 the relative current density and correspondingly to a change in the resist- 

 ivity-meter coefficient. 



It follows from (1) that: 



Jg_ 

 Av ' 



K 



(3) 



The potential difference Zly is proportional to the specific resistance q 

 of the fluid, to the distance / between the potential electrodes and to the 

 modulus j being the vector component of the current density at the middle 

 point between the measuring electrodes. Consequently equation (3) can 

 be wTitten as follows: 



K = 



K' 



_1_ 



y'o 



(3a) 



/ 



where /q = — is the relative current density. 



