Temperature dependence of the electrochemical potential in shaly sands and SP log interpretation

Temperature dependence of the electrochemical potential in shaly sands was studied on core samples from 20 ° to 80 °C. Using the Dual Water Model it was shown that the bound water volume increases with temperature. This effect was relatively high for brines and for shaly sands of low electrochemical activity. The SP reduction factor was very slightly affected by temperature. The possibility of evaluating water saturation in shaly sands using SP-GR logs was tested. A chart for evaluation of formation water resistivity was prepared from laboratory data. The results can help further development of well log petrophysical interpretation in hydrocarbon-saturated shaly sands.