The electrical behaviour of fully electrolyte-saturated reservoir rock samples has been represented through verified type curves as a continuum across a range of electrolyte resistivity. The type curves can be used to facilitate the well-log interpretation of clastic reservoirs for which the Archie porosity exponent is known or can be realistically assumed. They allow an immediate appreciation of the electrical characteristics of reservoir rocks and how these relate to other, previously studied formations. The type curves can be used with core or log data to infer whether a reservoir is behaving as effectively clean or shaly. In the case of effectively shaly sands, a single-point value of excess conductivity can be evaluated from log data alone. More generally, the type curves allow different reservoirs to be compared in terms of their electrical behaviours. Where these are similar, it is reasonable to assume that the petrophysical interpretation procedures will be similar for the reservoirs under consideration. Thus, the type curves allow a given reservoir to be characterized and evaluated within a generic framework of electrical behaviour. This, in turn, allows experience gained elsewhere to be brought to bear on the current appraisal, especially in terms of the identification of appropriate procedures for the well-log evaluation of hydrocarbons-in-place. Through this insight, the method constitutes a potential basis for greater confidence in petrophysically-supported reservoir models at an earlier stage in the evaluation of a field.