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Using Microbes to Vastly Increase Recovery from Old Oil Wells

The best source of oil would be to increase oil recovery from the existing reservoirs already in production.  That oil is the easy stuff as pundits like to say, because in reality we already know that the infrastructure is pretty much there.

A research team at Oregon State (OSU) has taken a new look at an old, but seldom used technique developed by the petroleum industry to recover oil, and learned more about why it works, how it could be improved, and how it might be able to make a comeback not only in oil recovery but also environmental cleanup.

That cleanup angle could give the research effort even more backing.

The Oregon State version of the technology is developed from technology called “microbial enhanced oil recovery” (MEOR), first developed decades ago.  But oil well operators largely lost interest in it due to its cost, inconsistent results and a poor understanding of what was actually happening underground.

The Oregon State University engineers’ new findings have been published in the Journal of Petroleum Science and Engineering.  The team’s new paper may offer a path the oil industry can use to produce more oil from their existing wells, but caould also find applications in cleaning up petroleum spills.

Microbial Enhanced Oil Recovery
Microbial Enhanced Oil Recovery View of Microbial Film Activity.

Dorthe Wildenschild, an associate professor in the OSU School of Chemical, Biological and Environmental Engineering explains that, “this approach of using microbes to increase oil recovery was used somewhat in the 1980s when oil prices were very high, but the field results weren’t very consistent and it was expensive. It’s seldom used now as a result.”

Oil production has always been difficult – it’s not as simple as drilling a hole and watching the petroleum gush out of the ground.  That may happen for a while, but as a secondary step, water is often injected into the well to help flush out more oil. Such production techniques generally recover only one-third to one-half of the oil originally present in a reservoir.

A third approach that was sometimes used after water injection is to inject microbes into the well and “feed” them with sugars such as molasses to encourage their growth. This activity can clog some pores and in others it has a “surfactant” effect, loosening the oil from the surface it clings to, much as a dishwasher detergent loosens grease from a pan.

Wildenschild explains, “By clogging up some pores and helping oil move more easily through others, these approaches can in theory be used with water flushing to help recover quite a bit more oil.”

The surfactant can be man-made, or microbes can be used to produce it at a lower cost. However, getting a particular culture of microbes to produce the biosurfactant under harsh field at high temperatures and pressure conditions is be a major challenge.

Wildenschild continues, “It’s complicated, you have to use just the right microbes, and feed them just the right foods, to accomplish what you want to do.”

In OSU laboratory experiments, Ryan Armstrong, a recent doctoral graduate at OSU, found that the clogging mechanism is the simplest and most effective approach to use, although combining it with the biosurfactant technology achieved optimal oil recovery.

The OSU team used Shewanella oneidensis (MR-1) that causes bioclogging, and Bacillus mojavensis (JF-2) that produces biosurfactant and causes bioclogging.  The idea was to focus on MEOR mechanisms of interfacial tension reduction (via the biosurfactant) and bioclogging in water-wet micromodels.

The micromodels were flooded with an assortment of flooding solutions ranging from metabolically active bacteria, to nutrient limited bacteria, to dead inactive biomass in order to assess the effectiveness of the proposed MEOR mechanisms of bioclogging and biosurfactant production.

Results of the experiments indicate tertiary flooding of the micromodel system with biomass and biosurfactant was optimal for oil recovery due to the combined effects of bioclogging of the pore-space and interfacial tension reduction. However, biosurfactant was only able to recover oil in some cases dependent on wettability. Biomass without biosurfactant that clogged the pore-space also successfully produced additional oil recovery.

The OSU team believes, and your humble writer agrees, a better fundamental understanding of this process – along with higher oil prices that better reward efforts to recover more oil – could lead to renewed interest in the technology on a commercial basis.

Then there is that cleanup angle . . . Either way or both – the research is pointing to a resumption of oil production from some really old fields and could very well equal or better all the oil produced so far.

By. Brian Westenhaus

Source: More Oil From Old Oil

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