Evaluation of Reservoir Condition Effects on the Reduction of Oil Viscosity by a Petrotoga strain Isolated from an Oilfield for MEOR

摘要

An anaerobic oil-degrading thermophile, Petrotoga sp. (Fig. 1), was isolated from reservoir brine of Yabase oilfield in Akita, Japan. This bacterium degrades long-chain hydrocarbons of crude oil into shorter-chain hydrocarbons selectively and reduces the viscosity of crude oil in brine medium. Because Petrotoga sp. has been founded exclusively from oil reservoirs before, this species is a typical indigenous microorganism in oil reservoirs (Olliver & Cayol, 2005). However, no strains of Petrotoga species which can reduce oil viscosity have been reported while six strains of Petrotoga species have been characterized so far (Davey et al, 1993 : Lien et al, 1998 ; L'Haridon et al, 2002 ; Miranda-Tello et al, 2004 ; Tello et al, 2007). Therefore, this strain is expected to be a promising microorganism for MEOR. The potential of this bacterium as a candidate for MEOR was estimated by investigating the influence of reservoir conditions such as temperature, salinity and pressure on the reduction of oil viscosity by this bacterium in this study.