Effect ofEOR Surfactant on Reservoir Rock Wettability

Th~: use of surfaGtant is proposed as on~: of the m~:thods to ~:nhance the
oil recovery from reservoir whereby the conventional methods such as
waterflood and production by natural drive are no longer sufficient to produce
the remaining oil. Primarily the ability of surfactant to reduce the oil-water
interfacial tension and alter the reservoir wettability making it a viable option
being explored today. 1FT reduction will increase the oil mobility thus
contributing for greater oil recovery. Wettability alteration from oil wet to water
wet or less oil wet will improve water imbibition. This study focus on the effect
of surfactant concentrations on reservoir rock wettability (contact angle).
Synthetic brine (Sodium Chloride, 1500ppm), crude oil (Baronia) and an ionic
surfactant (Sodium Dodecyl Sulfate, 0, 500, 1500, 3000 and 5000ppm) have
been used in this study. Sessile up or bubble technique has been used to obtain
the contact angle. A high speed magnifying camera produced a live video feed
that enable image capture of the oil bubble for contact angle analysis. The
contact angle is found to increase from 40.36° to 52.59° for the test with 0 ppm
and 500 ppm surfactant respectively. This change of wettability to less water wet
condition is discussed in the result and discussion sections. The experiment is
repeated for the 500 ppm and 1500 ppm surfactant concentration where the
contact angles were found to decrease from 40.24° to 25.20° respectively.