Experimental Study of the Effects of IFT and Hysteresis on Resistivity and Capillary Pressure of Carbonate Rocks

Characterizing the electrical resistance of the formation rock is of great importance in, for example, interpreting the well log data, calculating the porosity, and water saturation for the formation rocks. The relation between the resistivity factor and porosity and also between the resistivity index and water saturation (Archie equation) in the formation rock uses the parameters, such as the cementation factor and saturation exponent. However, the direct application of Archie equation to carbonate rocks that are very heterogeneous and mostly oil-wet needs further investigation. In this experimental work, the effects of overburden pressure, temperature, and interfacial tension on the capillary pressure and resistivity characteristics during the imbibition and drainage processes are studied. The results showed a decrease of the saturation exponent when the rock changes from the oil-wet to the water-wet, during the primary drainage (e.g., from 5.6 to 2.29), imbibition (e.g., from 3.98 to 1.93), and the secondary drainage (e.g., from 4 to 2.04). As a result, this study improves understanding of the reservoir rock behavior especially when the enhanced oil recovery processes are studied.