Speaker
Description
Wettability alteration is a widely accepted mechanism in enhanced oil recovery where modified salinity water improves oil mobilization in porous media by making reservoir rock more water wet. The equilibrium between phases in the Crude Oil-Brine-Rock (COBR) system defines the wettability state of the rock. As these properties will depend on the type of rock and crude oil it is crucial to identify each of these elements' role in the wettability alteration for a given reservoir. Contact angle measurement is an established qualitative approach to measuring the wettability state of a solid surface. In this research, we outlined a 25-1 fractional factorial design and conducted a series of dynamic contact angle measurements over 560 hours (3-4 weeks) to investigate the effect of chalk materials (reservoir and outcrop samples), brine chemistry including salinity (ranging from approximately 3000 to 50000 ppm), sulfate and magnesium concentrations (ranging from 0 to 700 and 0 to 1200 ppm, respectively), and different crude oil samples on wettability alteration. After initial contact angles were measured, 20 rock slices were aged for 4 weeks in two different crude oils at 70 °C. Then contact angles were measured again and rock samples were distributed amongst bine samples with a varying composition according to the experimental design, at the same temperature. For the next 560 hours measurements were done in the same way at regular intervals. During the aging phase, outcrop samples showed a more marked transition to oil wetness than the reservoir samples, which indicated a higher tendency to absorb polar components from the crude oil. It was also observed that the crude oil with a higher Total Acid Number (TAN) was able to alter the wettability more toward the oil-wet state for both types of rock samples. Consequently, it was observed that the wettability modification towards water wet is more easily achieved in the rock samples aged with the lower TAN crude oil. It was also noted that wettability alteration is a complex function of brine chemistry, where total salinity and individual ion concentration play a role. It should be noted that results obtained on reservoir rock samples contradict the general understanding in the literature, which has been developed primarily based on the results on outcrop samples. These results can be used to screen suitable reservoirs for wettability alteration based on their specific rock and fluid properties. Moreover, it provides evidence that injection water can be modified to alter wettability toward water-wet to enhance oil production through imbibition and viscous force mobilization.
| Participation | In-Person |
|---|---|
| Country | Denmark |
| MDPI Energies Student Poster Award | No, do not submit my presenation for the student posters award. |
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