Median Oil Droplet Size and Droplet Size Distribution
A small oil droplet size is critical to the stability of an oil-in-water emulsion. The oil-in-water emulsions produced by field processing normally have median droplet sizes ranging from 2 to 10 microns. These coarse emulsions allow oil to be dispersed in water for a few hours to a few days; however, physical separation "creaming" results if the suspensions are allowed to stand for a significant time period.

Droplet size is also critical for transport of oil-in-water emulsions through porous media. According to the filtration model described by Soo et.al., oil droplets must be < 1/3 the size of soil pore throats. Injection of pure vegetable oil or coarse emulsions may significantly reduce soil permeability. This is especially problematic for permeable reactive barrier wall installations where a loss of soil permeability may result in flow around the barrier.

The uniformity of droplet size within the emulsion is equally important. For example, injection of a field processed emulsion with a wide range of droplet sizes may contain a significant percentage of larger droplets, which could result in substantial permeability loss. The Newman Zone emulsion has a very small median droplet size & a very tight distribution of droplet sizes. The median droplet size of Newman Zone (volume distribution by laser diffraction analyses) is 0.3 to 0.4 microns, with 99.9% of the material consisting of droplets less than one micron.This allows injection of Newman Zone into most soil and bedrock formations with very little change in permeabilty.

The image on the left shows the best available field processing. The image on the right shows the Newman Zone factory emulsion.