Microbial selective plugging of sandstone through stimulation of indigenous bacteria in a hypersaline oil reservoir

Production of biomass by indigenous bacteria found in hypersaline ail-reser voir brine was limited by a fermentable carbon and phosphorus source. The a ddition of polymeric carbohydrates, such as maltodextrins, along with organ ic phosphates stimulated production of a flocculent and sometimes slimy bio mass, which was not produced from simple sugars. Maltodextrins also stimula ted production of lower levels of the endproducts acetate and ethanol. Inje ction of indigenous bacteria into sandstone cores followed by phosphate and maltodextrin resulted in a >90% reduction in the in-depth permeability of a sandstone core, whereas treatment with glucose resulted in primarily face -plugging of a sandstone core. These cornstarch maltodextrins and organic p hosphate esters have application as nutrients for stimulation of-biomass ne cessary for selective plugging of reservoir rock by microbial populations f ound in a hypersaline oil reservoir.