(n.) Reservoir Characterization. A process or procedure used to interpret petrophysical (usually wireline log) data. Usually representing a set of equations, algorithms or other mathematical processes, petrophysical models often have multiple routines. For example, a deterministicmodel might include routines that: calculate the hale olume; alculate total porosity; calculate effective porosity; calculate water saturation; calculate permeability. Often, the model is calibrated using core, production, test and other data sets. Although many software packages contain ready-built petrophysical models or component routines that can be called upon, many log-analysis problems are unique and require that "built to purpose" models be constructed. Construction of new petrophysical models is normally driven by the data available and the nature of the problem to be solved. (2) (n.) Reservoir Characterization. A model of a reservoi or a field in which the petrophysical data were the only or the primary data used to construct the model