Abstract
The efficient development of tight sandstone reservoirs is challenged by complex pore structures and heterogeneous remaining oil distribution. This study provides a quantitative pore-scale investigation into waterflooding mechanisms in the Changqing Oilfield’s C61 reservoir using Real Sandstone Micro-Models that preserve native pore geometry and wettability. Through integrated physical experiments and statistical analysis, we identified three displacement types (uniform, finger-like, reticulated) and found that permeability and pore-throat radius exhibit strong positive correlations with displacement efficiency (
R
2
> 0.75, p R
2
of 0.85 ± 0.04, RMSE of 2.51% ± 0.42%, and MAE of 1.98% ± 0.35% in repeated 5-fold cross-validation on the augmented dataset, and a LOOCV
R
2
of 0.76 with RMSE of 3.18% on the original 10 samples. Feature importance analysis suggests that permeability (importance score 0.38) and pore-throat radius (0.27) are dominant controls, with the variation coefficient (0.18) indicating a detrimental role of pore structure heterogeneity. This work provides an exploratory, data-driven framework for optimizing waterflooding strategies under the tested conditions, demonstrating a potential approach to maximize insights from limited experimental data. Generalization to other reservoirs requires validation on larger, independent datasets.