Using a breakthrough process, which does not require microbes to be injected, more than 100 microbial enhanced-oil-recovery (MEOR) treatments were conducted from 2007 to the end of 2010 in oil-producing and water-injection wells in the United States and Canada. On average, these treatments increased oil production by 122%, with an 89% success rate. This paper reviews the MEOR process, reviews the results of the first 100+ treatments, and shares what has been learned from this work.

Observations and conclusions include the following:

  1. Screening reservoirs is critical to success. Identifying reservoirs where appropriate microbes are present and oil is movable is the key.

  2. MEOR can be applied to a wide range of oil gravities. MEOR has been applied successfully to reservoirs with oil gravity as high as 41° API and as low as 16° API.

  3. When microbial growth is appropriately controlled, reservoir plugging or formation damage is no longer a risk.

  4. Microbes reside in extreme conditions and can be manipulated to perform valuable in-situ "work." MEOR has been applied successfully at reservoir temperatures as high as 200°F and salinities as high as 140,000 ppm total dissolved solids (TDS).

  5. MEOR can be applied successfully in dual-porosity reservoirs.

  6. A side benefit of applying MEOR is that it can reduce reservoir souring.

  7. An oil response is not always observed when treating producing wells.

MEOR can be applied to many more reservoirs than thought originallys with little downside risk. This review of more than 100 MEOR well treatments expands the types of reservoirs in which MEOR can be applied successfully. Low-risk and economically attractive treatments can be accomplished when appropriate scientific analysis and laboratory screening are performed before treatments.

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