Microbial Heavy Oil Viscosity Reduction and in situ Upgrading Bench Test Results

Abstract

The potential use of microorganisms to reduce heavy crude oil viscosity in situ and hence, improve recovery was investigated. Batch-flask tests, using pure cultures of selected microorganisms and indigenous microorganisms that were enriched from oil, sand and water samples taken from the reservoir, were performed under anaerobic conditions at 30^°C. The use of heavy oil as a sole carbon source and, the change in oil viscosity and in carbon numbers vs. boiling point were determined. Although none of the cultures tested was able to reduce the viscosity of the heavy oil, the simulated distillation analysis revealed that pure strain of Bacillus licheniformis could increase the recovery of light-end products. The oil fraction containing carbon numbers less than C₄₀₋was increased by about 30% after 21 days of anaerobic treatment.

Keywords:

• Heavy crude oil
• microbial enhanced recovery
• viscosity reduction
• anaerobic degradation
• in situ upgrading