Abstract
Low-salinity water (LSW) flooding is one of the newest EOR techniques which has more advantageous over other EOR techniques. This research employed a heterogeneous synthetic three-dimensional reservoir to model LSW flooding for a two-phase system including brine (high salinity to low salinity) and oil. The obtained results show that exact determination of salinity threshold and its wettability alteration coefficients are very important since they affect the maximum value of oil recovery. The oil recovery has been varied between 55.79 and 60.34% for a given injection brine salinity (500 ppm) at different salinity threshold values. Furthermore, the result reveals that aging time has a low effect on oil recovery which is around 0.066% after more than 12 years of injection. However, the fine-grid 1D simulation of a small sample demonstrates that the aging time effect should be considered in small-scale models. Furthermore, we prove that there is an optimum value of injection brine salinity for each reservoir according to its salinity threshold. Highest recovery changes occur at the salinity of 5000, 3400 and 1200 ppm for three different salinity thresholds approximately. This paper demonstrates that before any implementation of LSW flooding, many laboratory tests must be done at reservoir condition to precisely detect wettability alteration coefficient, the best injection brine salinity and flow behavior from high-salinity water to LSW.
Highlights
Laboratory tests and field applications have shown that low-salinity water (LSW) injection is one of the valuable EOR methods in terms of its advantageous in chemical cost, environmental impact and field-scale implementation compared to conventional chemical EOR methods (Dang et al 2013; Zeinijahromi et al 2015)
The first signs of prospective oil recovery improvement during LSW flooding are corresponding to a study carried out by Reiter (1961), when he found an increase in oil production rate within water injection at different salinities
Narrow ranges of salinity threshold might have an adverse effect on oil recovery during low-salinity water flooding because wettability alteration process happens at later times after low-salinity water injection and it takes more time to reduce the brine salinity to such a low value; for instance, 2000 ppm in the model#3
Summary
Laboratory tests and field applications have shown that low-salinity water (LSW) injection is one of the valuable EOR methods in terms of its advantageous in chemical cost, environmental impact and field-scale implementation compared to conventional chemical EOR methods (Dang et al 2013; Zeinijahromi et al 2015). Shojaei et al (2015) performed a series of experimental LSW flooding tests on a sandstone core aged with crude oil and obtained the relative permeability and capillary pressure curve using Sandra simulator through history matching method They indicated that residual oil saturation changed linearly with injection brine salinity due to the IFT reduction and wettability alteration toward more water-wet. In another study, Omekeh et al (2012) coupled a MIE process relevant to a standard Buckley–Leverett two-phase model to study the wettability alteration mechanism in an oil-wet sandstone rock during LSW flooding They observed that various compositions of brine give different oil recovery curves as the result of different ranges of divalent ions (calcium and magnesium) desorption.
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 callMore From: Journal of Petroleum Exploration and Production Technology
Disclaimer: 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.
