Construction of Capillary Pressure and Relative Permeability by Using NMR Data for Sarvak Formation in SW Oil Fields of Iran

Determining and estimating reservoir properties such as capillary pressure and relative permeability are always challenging in reservoir studies. The current research has been done in the Sarvak Formation in the southwestern oilfields of Iran, focusing on applying Nuclear Magnetic Resonance (NMR) logging in synthesizing capillary pressure and relative permeability. In this study, the Sarvak Formation in the studied well was divided into three flow units using the Hydraulic Flow Unit method. Then, for each separate flow unit, the capillary pressure curves were calculated and illustrated from the NMR T2 distribution data. Next, the calculated capillary pressure curves were corrected concerning the laboratory capillary pressure data derived from SCAL. Then, the conversion factor to calibrate well log-derived Pc curves to SCAL Pcs was determined for each flow unit. Afterward, mathematical functions for capillary pressure curve estimation were written using MATLAB software. Next, the relative permeability for oil and water phases was calculated and plotted in MATLAB software based on the functions determined in the previous step. Finally, the representative capillary pressure curve and relative permeability curve of the oil and water phases were determined for each flow unit. The results showed an increasing trend in the reservoir quality from flow units 1 to 3. Flow unit 3 had the lowest capillary pressure with the highest relative permeability and, consequently, better reservoir quality. In contrast, flow unit 1 had the highest PC levels, the lowest relative permeability, and the lowest reservoir quality.