Data-driven analyses of low salinity water flooding in sandstones

Low salinity water flooding (LSWF) has been intensively investigated but the conditions for LSWF to work are still unclear and the EOR mechanisms are still debatable. In this study, we extracted data from hundreds of LSWF flooding tests using sandstone cores and sand packs that have been published to date (by January 2018), and analyzed the tertiary recovery results (202 groups) collectively. First, all initial experimental conditions are correlated to the tertiary recovery factors in both single and combinatorial manners. Correlation charts show that no single experimental condition constitutes necessary or sufficient conditions for incremental oil recovery; combinatorial conditions show stronger correlations with the recovery factors, but still do not constitute sufficient conditions for incremental oil recovery. Secondly, incidental property changes are correlated to tertiary recovery factors in order to evaluate the related EOR mechanisms. Wettability alteration towards more water-wet shows a strong correlation with improved oil recovery. Finally, all previously proposed EOR mechanisms for LSWF in sandstones are linked in a chart to demonstrate an in-depth overview of all these mechanisms. We use experimental data analyses to provide a solid basis for reviewing LSWF and provide unique perspectives in understanding this process.