SINCLAIR OIL A GAS COMPANY. GEO. CHEMICAL LABORATORY, TULSA, OKLA. 

 PATTERN WATER ANALYSIS SYSTEM 

 SCALE: MEQ. PER LITER 



5o*a 



5<#B 



75*1 



25* B 



Mg 



Figure 13-4. Water-analysis patterns. 



ELECTRIC RESISTIVITIES A knowledge of the resistivity of formation 

 OF OIL-FIELD BRINES waters is essential for the fullest utilization of, 



the electric log. The resistivity of formation 

 waters may be measured directly with a resistivity meter or calculated from the 

 mineral analyses, a procedure which eliminates the need of estimating formation- 

 water resistivity and should result in increased accuracy of quantitative log 

 interpretation. Water-resistivity data also are useful for determining casing 

 leaks in wells and for identifying geological formations. The resistivity of waters 

 varies with temperature and with both the quantity and type of salts in solution. 



WATER RESISTIVITY Resistivity of water is denned as the property 



of water that resists the flow of an electric 

 current. The unit most generally used in electric-log interpretation is the ohm- 

 meter (ohm), which expresses the resistance in ohms of one cubic meter of 

 water to the flow of a uniform electric current parallel to one side of the cube. 

 Water resistivities sometimes are expressed in ohm-meters squared per meter 

 (ohm-m 2 /m), or in ohm-centimeters (ohm-cm). Conversion factors that have 

 been determined experimentally permit conversion of the various ionic concen- 

 trations, as determined by water analysis, to equivalent concentrations of sodium 

 chloride. The sum of equivalent concentrations gives the equivalent sodium- 



256 



