Pore structure is a crucial attribute in characterizing fluid flow through porous media. However, direct experimental measurements or numerical reconstructions are commonly expensive and not environmentally friendly, with great uncertainty caused by the complex nature of porous media. In this study, we demonstrate that one special bridge function, which is a function of the apparent length and tortuosity fractal dimension, can characterize the relationship of pore structures between two dimensions (2‐D) and three dimensions (3‐D), and it can serve as a conversion bridge of the radius to determine the capillary pressure curve (CPC). We compare estimations by the proposed method with experimental results obtained by mercury intrusion porosimetry in six typical natural sandstones with varying porosities and permeabilities. The result shows that cross sections of the global pore structure, such as thin section, electronic probe, and microcomputed tomography slices, give a reliable estimation of the CPC using the bridge function in porous media with a medium porosity. However, in unconventional porous media with a relatively low porosity (~10%) or extra high porosity (~30%), due to the empirical nature of the equation widely used to calculate the tortuosity fractal dimension, the necessary modification is necessary to obtain the CPC when applying the bridge function in such porous media. This insight can significantly simplify the procedure for obtaining the petrophysical properties of a porous medium, which may shed light on the inherent differences and correlations between the 2‐D and 3‐D pore structures of porous media.

Deterministic rock physics models were applied in a shale-sand environment located in the West African lower Congo basin, with the aim of estimating total porosity and clay content from P-wave acoustic impedance. Assuming that the only minerals within the target reservoir are quartz and clay, Han et al. model was used to determine the clay content which is referred herein as model-based C, while Krief et al. model was applied to solve the P-wave impedance for total porosity and clay content. The latter operation is a challenging task because of the nature of the actual rock physics equation that relates the known acoustic impedance to three unknown reservoir properties. This inherent difficulty is circumvented by making use of an additional linear equation, which is derived from the petrophysical link between porosity and clay content. To achieve this goal, firstly, a rock physics model was established, and then the reservoir was delineated through a combination of P-wave impedance and Poisson’s ratio. In the reservoir, total porosity and clay content were inverted based on P-wave impedance by applying the rock physics model of Krief et al. that related P-wave impedance to total porosity and clay content, alongside the established petrophysical link between the two reservoir properties. The result was found to be consistent on the well log scale. Uniquely, a good match was obtained when the methodology was repeated on the real seismic data.