While the use of bacteria to plug the high permeability zones that cause water breakthrough in waterflood operations has been suggested repeatedly for several decades, field operations have met with only intermittent success. We have used starvation to reduce normal-sized (±1.0 μm), naturally adherent, vegetative bacterial cells to very small (±0.3 μm), non-adherent ultramicrobacteria (UMB) that penetrate rock and sand matrices very readily. When UMB are injected into sand or rock >180 milliDarcies inpermeability, these very small, non-adherent cells are readily transported deep into the pore spaces. As they penetrate, some UMB are retained in the pore structures and, when the matrix is flooded with a suitable nutrient, these small, starved cells return to their full vegetative size and their normal high level of exopolysaccharide slime production. Within days of nutrient flooding, the permeability of the bacteria-treated high permeability zones is reduced by at least 99%.

This novel biotechnology is presently being licensed for field testing in the prevention of coning and in the selective plugging of high permeability zones in waterflood operations.

You can access this article if you purchase or spend a download.