Capillary pressure and other special core properties are usually determined using the laboratory analysis of the reservoir cores. The determination of the capillary pressure in the laboratory depends on several factors such conditioning the laboratory to the reservoir conditions. The actual simulation of the reservoir conditions could be difficult in certain situations because transferring the cores from the reservoir to the surface this will cause changes in the pore geometry and fluid compositions. The capillary pressure was determined using different correlations that based on the water saturation and lithology factor for specific formations.
In this study, a new method will be introduced to determine the capillary pressure from the resistivity log measurements. Resistivity logs that will be used are: Deep Induction Log (ILD), Medium Induction Log (ILM) and Micro- Spherical Focused Log (MSFL). The actual log measurements from the downhole will be used to determine the capillary pressure profile in the transition zone versus water saturation. Moreover, this method also can be used to predict the initial condition of the wettability in the reservoir. Lithology and porosity logs also will be used to help in determination the clean and shaly formation, water saturation, and the selected zones permeability, therefore, the effect of shale on the capillary pressure profile can be investigated.
Predicting the capillary pressure profile from the resistivity data proved to be a very good technique in characterizing the reservoir. The capillary pressure profile can be determined for the actual formation conditions downhole without the need to do laboratory tests which at the end will not give accurate profile measurements. The predicted capillary pressure matched the measured capillary pressure in the laboratory at medium permeability range (100-250 md) in carbonate reservoirs and low permeability range in sandstone reservoirs (less than 60 md).