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Abstract

Injection of low salinity water has been reported in the literature to improve oil recovery in some sandstone reservoirs, but some disappointing results have also been reported for other reservoirs. Different low salinity water flooding (LSWF) mechanisms have been proposed, but no mechanism has been widely accepted. These mechanisms are therefore still discussed. Understanding how the brine and oil components interact with the minerals in the reservoir rocks is necessary to establish more knowledge about the LSWF mechanisms. In the presented study the objective has been to investigate the retention of polar crude oil components onto minerals and reservoir rock (with high clay content) in equilibrium with brines of different salinities/compositions. The interactions between minerals/reservoir rock, oil and brine were then studied in both static and dynamic experiments. These results have been compared with results from core flooding studies carried out to study the effect of different brine compositions on the oil recovery in the same reservoir rock. The experiments have demonstrated that change of injection brine from high to low salinity/composition can significantly change the retention of polar oil components onto minerals and reservoir rocks. When the injection brine is changed, the amounts of divalent cations onto clay surfaces can depending on the compositions of these brines either increase or decrease. The wettability conditions of the rock can therefore either be altered to less water-wet or more water-wet. The results from the study of retention of polar crude oil components were in accordance with flow characteristics in the core flooding studies carried out in the same reservoir rock. It is concluded that the first evaluation of the potential for low salinity water flooding for improving oil recovery can be carried out by measuring the difference in retention of polar crude oil components for the high and low salinity brine compositions. The potential for different possible low salinity water compositions can also be evaluated by measuring the retention of oil components in the presence of these brines.

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/content/papers/10.3997/2214-4609.20142611
2013-04-16
2024-03-28
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http://instance.metastore.ingenta.com/content/papers/10.3997/2214-4609.20142611
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