ENHANCED OIL-RECOVERY - 3-DIMENSIONAL SANDPACK SIMULATION OF ULTRAMICROBACTERIA RESUSCITATION IN RESERVOIR FORMATION

Changes in cell size and shape associated with bacterial starvation and resuscitation were used as a technique to enhance oil recovery. Injection of starved bacteria followed by nutrients into rock cores produced deep bacterial plugs. This work reports on an investigation of the dispersion and resuscitation of ultramicrobacteria (UMB) produced by starvation of Pseudomonas sp. FC3. Initially, the UMB were injected into one-dimensional sandcores; in other words, flow was from the inlet to the outlet in one direction. To provide closer simulation of oil well conditions, the UMB were injected into a three-dimensional reservoir simulator, 45 cm in diameter by 38 cm in length. Sample probes strategically positioned within the sandpack detected the UMB as they dispersed throughout the pack. After 24 d of nutrient stimulation, the sandpack was dismantled and analysed. Scanning electron microscopy and carbohydrate assays of the sandpack sections showed glycocalyx (polymer) production in every section. The three-dimensional model confirmed the findings of the unidirectional core models in that the UMB penetrated the sandpack, resuscitated and grew in situ to form a confluent bacterial plug when nutrient-stimulated.