Novel Methods for Cost-Effectively Generating a Heterogeneous Core Model Based on Scale Change of Nuclear Magnetic Resonance and X-ray Computed Tomography Data

Abstract

In response to the constraint on model size imposed by computational capabilities and the inability to capture the heterogeneity within the core and its dynamic oil displacement characteristics, this paper proposes two novel methods for cost-effectively modeling heterogeneous core models based on scale changes of nuclear magnetic resonance (NMR) and X-ray computed tomography (X-CT) data, respectively. By utilizing NMR and X-CT techniques to characterize information at the subcore scale, we establish a more realistic model at the core scale. First, by using a method of setting up inactive grids, a homogeneous model is established to better represent the actual cross-section of the core. By fitting the core water displacement experimental data, a random heterogeneous core model based on the NMR-T2 spectrum is established by using the modified Schlumberger-Doll Research (SDR) model and complementarity principle. The numerical simulation results show that the random heterogeneous core model partially reflect the heterogeneity of the core, but the simulation results are unstable. Building on this, a deterministic homogeneous core model is established based on X-CT scan data by using the modified Kozeny-Carman model and pore extraction method. Sensitivity analysis results suggest that higher grid accuracy leads to a better fitting effect, with the axial plane grid accuracy impacting the model water-drive process more significantly than that of the end plane. The study paves the way for the rapid and accurate establishment of core models.