The Hughes Eastern Corporation project is demonstrating how naturally occurring varieties of microbes in an oil reservoir can be used to increase crude oil production. Supplied with the proper nutrients, these bacteria can grow rapidly. Whereas certain strains can be used to thin oil so that it will move more easily through the reservoir rock, other types of microbes can form gels to change the flow paths of water and oil through the formation. Hughes Eastern is using these latter types to effect beneficial changes in reservoir fluid flow patterns. In the North Blowhorn Creek field near Vernon, Alabama, as in many domestic fields, oil is being produced by waterflooding-injecting water to force oil towards producing wells. After many years, portions of the reservoir have been "swept" of much of the remaining producible oil, but other areas, bypassed during the waterflooding, still contain significant amounts of "unswept" oil. Hughes will use the natural microbes to plug the water-swept parts of the reservoir, thereby diverting injected water to the bypassed oil-containing zones. Core samples from Iwo new wells drilled in early 1994 indicated that this area of the reservoir had not been swept by the waterflood and contained significant amounts of producible oil. Laboratory testing also showed that, when water containing common plant fertilizers was passed through the core samples, the natural microbes grew, plugged the pore spaces in the rock, and increased the resistance to water flow. Further testing helped researchers learn what mixture of fertilizer and water best stimulated microbial growth. Hughes began injecting the selected fertilizer mixes in four well patterns in late 1994 and early 1995. Staff are monitoring each pattern's injection capacity and oil and water production rates, and checking for indications of microbial effects. Initial production increases were noted, but major changes are not expected for some time.