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