Subresolution Porosity Estimation of Porous Rocks from CT Images: Incorporating X-Ray Mass Attenuation Coefficients

Rock porosity is a key parameter for quantifying fluid flow properties and predicting mechanical behaviour. Although X-ray CT imaging has been widely used to estimate porosity, the accuracy of such methods is still hindered by beam energy and mineralogical heterogeneity. In this study, a methodology for the estimation of subresolution porosity is proposed, taking into account the relative relationship of X-ray mass attenuation coefficients (MACs) among minerals. The approach segments macroparticles, matrix, and macropores and calibrates their relative X-ray MAC relationships to establish the upper and lower bounds of the matrix LAC. Subresolution porosity is then estimated based on these calibrated limits. Taking Belgian Fieldstone and Bentheimer Sandstone as examples, the method described in this paper has stronger connectivity than does the binarised porosity estimation method and higher estimation accuracy than does the subresolution porosity calculation method, which does not consider the MAC. The proposed method is intended to refine the rationality of the subresolution porosity calculation and to broaden its theoretical scope of application.