Abstract

Reservoir permeability is an important parameter in reservoir evaluation and the research on surplus oil distributing regularities. However, it is difficult to calculate it accurately in the process of reservoir interpretation. The ordinary interpretation model uses the rough linear relationship between porosity and permeability within a semi-log coordinate system, resulting in much error. In this paper the permeability calculating formula, including three parameters, porosity, pore-throat radius and pore tortuosity, was deduced from the unity of Poiseuille Capillary Model and Darcy’s Law. Based on that, data of core physical properties analysis, mercury injection and well logging were used to construct the empirical relationship between pore tortuosity and pore-throat radius, thus realizing the transformation of permeability calculation from the solo empirical model to the semi-theoretical and semi-empirical model. The calculated results showed that the relative error of the new model was 20.26%, with 22.46 percentage points lower than the error of the traditional empirical model.

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