Novel Methods

A number of NETL projects investigate EOR approaches outside the mainstream. Among them are technologies that entail reducing oil viscosity by heating the formation with microwave, electric, or acoustic energy; or increasing oil mobility by shaking it with seismic vibrations.

One NETL project resulted in the design of a set of standards to be met by field demonstrations of sonic stimulation, field experiments to determine the far-field characteristics of the various sonic sources in use today, and fundamental observations to advance theoretical understanding of the sonication process.

Another novel EOR approach entails research into influencing wettability—essentially, the affinity of a solid for a certain liquid or gas in preference to another. Wettability studies to influence oil-wet (rocks with a preference for imbibing oil) and water-wet conditions and to design a brine to reverse wettability show promise for future EOR recovery.

The novel EOR technology that has attracted the most research over the years is microbial EOR (MEOR).

MEOR relies on microbes to ferment hydrocarbons and produce a by-product that is useful in the recovery of oil. MEOR functions by channeling oil through preferred pathways in the reservoir rock by closing/ plugging off small channels and forcing the oil to migrate through the larger pore spaces. Nutrients such as sugars, phosphates, or nitrates frequently must be injected to stimulate the growth of the microbes and aid their performance. The microbes generate surfactants and carbon dioxide that help to displace the oil.

Microbial growth can be either within the oil reservoir (in situ) or on the surface where the by-products from microbes grown in vats are selectively removed from the nutrient media and then injected into the reservoir. For in-situ MEOR processes, the microorganisms not only must survive in the reservoir environment but also must produce the chemicals necessary for oil mobilization.

A more detailed discussion of microbial processes and details of some NETL MEOR projects can be found on the Microbial Processes page.