Chemical Induced Wettability Alteration of Carbonate Reservoir Rocks

Wettability alteration of outcrop obtained from Asmari formation was investigated using surfactants. Three different surfactants including a cationic surfactant: dodecyltrimethylammonium bromide (DTAB), an anionic surfactant: sodium dodecylbenzenesulfonate (SDBS) and a non-ionic surfactant that was Triton X-100 were used.
Wettability alterations in the presence of each surfactant for the three surfactant concentrations from 0.1 to 0.3 wt% in brine and at four different temperatures, from 25 to 80oC were examined. Surfactant solution droplets were placed on the rock surfaces after being saturated with brine and placed in crude oil. The potential of surfactants to alter the wettability was determined by estimating the contact angle (θ) between the surfactant droplet and the surface of the rock. The results indicated that Triton X-100 could change the wettability condition from oil-wet to water-wet more than other surfactants with the same concentrations and temperatures.