WETTABILITY STUDY OF SAUDI-ARABIAN CARBONATE RESERVOIR CORE SAMPLES

A wettability study of carbonate rocks from a Saudi Arabian reservoir was conducted based on three widely used quantitative laboratory techniques: USBM, Amott, and contact angle. During the course of this study, wettability was evaluated using reservoir produced brine and filtered stock-tank oil. Several pertinent factors affecting wettability were investigated while maintaining a fixed crude composition. Synthetic brines varying in salinity were tested under elevated temperature and pressure conditions. Other factors studied included pressure, temperature, core exposure to air, and core cleaning. Both preserved and cleaned carbonate cores were used during the USBM and Amott wettability tests, whereas, smooth calcite crystals were prepared for contact angle wettability measurements. The effects of brine concentration, pressure, temperature, core cleaning, and core exposure on wettability of the carbonate cores were also studied and provided adequate understanding of the wettability of the carbonate rock/fluid system. USBM and Amott tests indicated that the subject carbonate reservoir rocks were intermediately wet. Contact angle measurements, however, yielded moderate water wetting.