Produced water is underground formation water that is brought to the surface along with oil or gas. It is by far the largest (in volume) by-product or waste stream associated with oil and gas production. Management of produced water presents challenges and costs to operators. If the entire process of lifting, treating, and reinjecting can be avoided, costs and environmental impacts are likely to be reduced. With this idea in mind, during the 1990s, oil and gas industry engineers developed various technologies that separate oil or gas from water inside the well. Two basic types of DOWS have been developed. One type uses hydro cyclones to mechanically separate oil and water, and the other relies on gravity separation that takes place in the well bore.

Reprinted with Permission from Argonne National Laboratory