The Application of Kozeny–Carman Model Optimized Based on Fractal Theory in Mixed Shale Oil Reservoirs

ABSTRACT In oil and gas exploration, permeability is a key parameter that affects the flow and extraction efficiency of oil and gas. The traditional Kozeny–Carman (KC) equation, based on the assumption of uniform porosity, is difficult to accurately predict the permeability of reservoirs with complex pore structures such as shale and tight sandstone. This article takes the mixed shale oil reservoir of the Lucaogou Formation in the X depression of the Junggar Basin as the research object. Aiming at the problems of complex lithology and significant physical property heterogeneity of the reservoir, a New KC (NKC) model based on fractal theory optimization and considering lithological differences is constructed. This model quantifies the power‐law distribution characteristics of pore radius through pore fractal dimension (). The curvature degree of the fluid path is characterized by the tortuosity fractal dimension (). The arithmetic mean pore radius in the traditional model is upgraded to the area‐weighted average radius, and lithological differences are taken into account. The application results show that the mean square error (MSE) of the NKC model is 101.03, which is lower than 132.64 of the traditional KC model and 143.14 of the Standard Deviation Reduction (SDR) model. The correlation coefficient is as high as 0.8066, which is better than 0.3968 and 0.2518 of the traditional model. The NKC equation optimized on the basis of fractal theory constructed in this study can more accurately describe the heterogeneity of reservoir physical properties and can provide more reliable technical support for the permeability evaluation of similar complex lithologic reservoirs in the study area.