Wettability alteration of carbonate rock mediated by biosurfactanat produced from high-starch agricultural effluents

A16 - 9th International Wettability Symposium, Bergen, Norway, 18-19 September 2006

ABSTRACT: Surfactants can be used to alter wettability of reservoir rock, increasing spontaneous
imbibition and thus improving oil yields. Commercial synthetic surfactants are often
prohibitively expensive and so a crude preparation of the anionic biosurfactant, surfactin,
from Bacillus subtilis, able to be grown on high-starch industrial and agricultural effluents,
has been proposed as an economical alternative. To assess the effectiveness of the
surfactin, it is compared to a commercially available surfactant. The wettability change
mediated by dilute solutions of commercial anionic surfactant (STEOL CS-330) and
surfactin was assessed using two-phase separation, and water flotation techniques; and
surfactant loss due to retention and adsorption the rock was determined. Qualitative tests
indicate that on a molar basis, surfactin is more effective than STEOL CS-330 in altering
wettability of crushed Lansing-Kansas City carbonates from oil-wet to water-wet state.
Adsorption isotherms of STEOL CS-330 and surfactin on crushed Lansing-Kansas City
outcrop and reservoir material showed that surfactin has higher specific adsorption on
these oomoldic carbonates.