Abstract
Water flooding is widely applied for pressure maintenance or increasing the oil recovery of reservoirs. The heterogeneity and wettability of formation rocks strongly affect the oil recovery efficiency in carbonate reservoirs. During seawater injection in carbonate formations, the interactions between potential seawater ions and the carbonate rock at a high temperature can alter the wettability to a more water-wet condition. This paper studies the wettability of one of the Iranian carbonate reservoirs which has been under Persian Gulf seawater injection for more than 10 years. The wettability of the rock is determined by indirect contact angle measurement using Rise in Core technique. Further, the characterization of the rock surface is evaluated by molecular kinetic theory (MKT) modeling. The data obtained from experiments show that rocks are undergoing neutral wetting after the aging process. While the wettability of low permeable samples changes to be slightly water-wet, the wettability of the samples with higher permeability remains unchanged after soaking in seawater. Experimental data and MKT analysis indicate that wettability alteration of these carbonate rocks through prolonged seawater injection might be insignificant.
Highlights
More than 60% of the world’s oil in place is located in the Middle East, with over 70% being reserved in carbonate formations
Experimental studies showed that potential-determining ions in seawater, Ca2+, Mg2+, and SO24−, have a great influence on wetting characteristics of carbonate rocks toward water wetting and their efficiency increased at high temperatures (Austad et al 2005; Zhang and Austad 2006; Strand et al 2006)
The results suggest that seawater may slightly change the wettability of carbonate rocks which are consistent with the findings reported in other studies
Summary
More than 60% of the world’s oil in place is located in the Middle East, with over 70% being reserved in carbonate formations. Spontaneous imbibition and forced fluid displacement results revealed that seawater is more effective in enhancing oil recovery than the injection of brine free of sulfate ions at temperatures higher than 100 °C (Zhang et al 2007; Austad et al 2008; Strand et al 2008; Alotaibi et al 2010). Since the levels of potential-determining ions in seawater and crude oil composition are different from place to place, the wetting condition of the Middle East carbonate oil fields was slightly changed after seawater flooding (Alotaibi et al 2010; Okasha 2014; Zhu et al 2016)
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
