TY - GEN
T1 - Understanding the chemical mechanisms for low salinity waterflooding
AU - Qiao, Changhe
AU - Johns, Russell
AU - Li, Li
PY - 2016/1/1
Y1 - 2016/1/1
N2 - Low salinity water (LSW) is reported to improve oil recovery (IOR) significantly in sandstone and carbonate core experiments. Ranges of IOR vary significantly depending on the chemical composition of brine, oil and cores. We previously developed a process-based and predictive model that explicitly includes the chemical interactions between crude oil, brine, and the carbonate surface that alter rock wettability. In this research, we improve the developed model to include explicitly the acid/base interaction and ion-binding interaction of crude oil adsorption. The wettability alteration is quantified by the surface concentrations of adsorbed carboxylic acids, which is a result of aqueous and surface reactions. The total concentrations of aqueous and surface species are varied individually and together over a large range while precipitation constraints are also included. The wettability is for a variety of brine compositions used in experiments. The wettability depends strongly on the concentration of Ca2+, Mg2+ and SO42-, as well as the total salinity. Including the acid/base interaction can explain the wettability alteration trend when Ca2+, Mg2+ and SO42- concentrations are significant. Including the ion-binding through Ca2+ can better explain the wettability alteration trend when diluted formation water or seawater is injected. We can reproduce the wettability alteration trend reported in experiments from different sources by combining the acid/base and ion-binding mechanisms and considering the irreversibility of the carboxylic adsorption reactions.
AB - Low salinity water (LSW) is reported to improve oil recovery (IOR) significantly in sandstone and carbonate core experiments. Ranges of IOR vary significantly depending on the chemical composition of brine, oil and cores. We previously developed a process-based and predictive model that explicitly includes the chemical interactions between crude oil, brine, and the carbonate surface that alter rock wettability. In this research, we improve the developed model to include explicitly the acid/base interaction and ion-binding interaction of crude oil adsorption. The wettability alteration is quantified by the surface concentrations of adsorbed carboxylic acids, which is a result of aqueous and surface reactions. The total concentrations of aqueous and surface species are varied individually and together over a large range while precipitation constraints are also included. The wettability is for a variety of brine compositions used in experiments. The wettability depends strongly on the concentration of Ca2+, Mg2+ and SO42-, as well as the total salinity. Including the acid/base interaction can explain the wettability alteration trend when Ca2+, Mg2+ and SO42- concentrations are significant. Including the ion-binding through Ca2+ can better explain the wettability alteration trend when diluted formation water or seawater is injected. We can reproduce the wettability alteration trend reported in experiments from different sources by combining the acid/base and ion-binding mechanisms and considering the irreversibility of the carboxylic adsorption reactions.
UR - http://www.scopus.com/inward/record.url?scp=84992154262&partnerID=8YFLogxK
UR - http://www.scopus.com/inward/citedby.url?scp=84992154262&partnerID=8YFLogxK
M3 - Conference contribution
AN - SCOPUS:84992154262
T3 - Society of Petroleum Engineers - SPE Europec Featured at 78th EAGE Conference and Exhibition
BT - Society of Petroleum Engineers - SPE Europec Featured at 78th EAGE Conference and Exhibition
PB - Society of Petroleum Engineers
T2 - SPE Europec Featured at 78th EAGE Conference and Exhibition
Y2 - 30 May 2016 through 2 June 2016
ER -