ABSTRACT
Primary oil recovery relies on the energy within the reservoir to force the oil through the porous rock to the production well. Enhanced recovery methods are intended to extract more of this oil. The techniques are divided into four broad groups: chemical, miscible gas, thermal, and "exotic," in which last category lies in situ microbial enhanced oil recovery (MEOR). The in situ methods proposed for enhanced recovery of oil therefore, involve injection of selected microorganisms into the reservoir and the stimulation of their growth in situ so that their presence and activity leads to the increased production of crude oil. The oil "majors" are now exploring the more "conventional" EOR processes and are sure to be considering the potential of both ex situ and in situ MEOR methods. The screening of suitable cultures for oil mobilization by microbial mechanisms is carried out in a sandpack and reservoir core apparatus in a similar fashion to that used for screening EOR chemicals.
