PERMEABILITY ESTIMATION - THE VARIOUS SOURCES AND THEIR INTERRELATIONSHIPS

Rock-formation permeability is one important flow parameter associated with subsurface production and injection. Its importance is reflected by the number of available techniques (well-log evaluation, core measurements, and well testing) typically used to estimate it. The literature is full of comparisons and correlations of permeability from these sources. Too often these comparisons and correlations are used to make important conclusions without proper regard to the interrelationships among them. Permeability estimates by individual techniques within the various permeability sources can vary with the state of rock (in-situ environment), fluid saturation distribution, flow direction, and the scale of the medium under investigation. This paper reviews the commercially available permeability-estimation techniques and discusses the important factors that illustrate their interrelationships. Knowledge of appropriate interrelationships among the various techniques allows meaningful permeability comparisons and correlations. Usefulness of the interrelationships is demonstrated with field data. Also, the interrelationship concepts presented are a cornerstone for reservoir flow characterization.