Two-Phase Relative Permeability Curves Based on In Situ X-ray Computed Tomography

Relative permeability curves constitute a fundamental basis for characterizing multiphase flow behavior in reservoir engineering, and their accuracy directly determines the reliability of production forecasting, development strategy optimization, and enhanced oil recovery design. X-ray computed tomography (CT) provides quantitative visualization of fluid flow within porous media, transforming conventional macroscopic, inversion-based black-box observations into transparent, mechanism-oriented analyses. In this study, an improved relative permeability fitting method based on CT scanning was proposed. Water saturation distributions at various displacement stages were quantified from CT data using relevant computational formulas, enabling accurate characterization of multiphase flow behavior within core samples. By employing the Corey relative permeability model and establishing a linkage between CT-derived water saturation and produced water cut, the unknown parameters were fitted, and two-phase relative permeability curves were constructed. Core samples of dolomite and limestone from the A oilfield in Iraq were then analyzed using the proposed method to obtain relative permeability curves and to investigate flow behavior in reservoirs with complex lithologies. Compared with conventional unsteady-state approaches commonly used for relative permeability determination, the proposed method requires fewer fitting parameters, achieves higher accuracy, and exhibits broader applicability, including but not limited to oil–water systems. This study not only expands the application of CT technology in multiphase flow research but also provides a more feasible and robust approach for the determination of relative permeability curves.