Wettability alteration of mica and sandstone by a biosurfactant-producing bacterium Bacillus thermodenitrificans SUCPM-23, isolated from an oil reservoir

The effects of growth and metabolite production of a variant of bacillus thermodenitificans on the surface properties and wettability of mica and sandstone cores were investigated. Measured contact angles on mica plaques showed more oil wetness for three different types of treatment using the bacterium , a non-biosurfactant - produing mutant and the extracellular biosurfactant. AFM analyses of the mica surfaces reveales noticeable surface changes for all the treated samples compared with untreated mica . the nature and the extent of changes varied for the three methods of treatment . wettability alteration toward less water-wet was also observed for sandstone core samples treated by the biosurfactant solution and by the non-biosurfactant -producing mutant. it is demonstrated that wettability alteration takes place both in the presence and in the absence of extracellular suface-active compounds and that both methods of treatment lead to less affinity for water.

Keywords:

biofilms , biosurfactants , wettability , microbial enhanced oil recovery , atomic force microscopy.