Mechanisms and Optimization of Foam Flooding in Heterogeneous Thick Oil Reservoirs: Insights from Large-Scale 2D Sandpack Experiments

In this study, a 5 m×1 m×0.04 m sand filling model was constructed to simulate Lukqin thick oil reservoir, and the development rules of water flooding and foam flooding were systematically analyzed. The results show that the recovery rate of water flooding is only 30% due to the imbalance of mobility ratio and gas channeling. By integrating electrical resistivity tomography (ERT) with HSV (Hue-Saturation-Value) color mapping, this study pioneers the first visualization of foam migration in meter-scale heterogeneous reservoirs (5 m × 1 m × 0.04 m) with a spatial resolution of ≤0.5 cm. This surpasses the limitations of conventional CT scanning (typical resolution ≥2 cm) and X-ray tomography (cost: 500–800 per scan), offering a 30% reduction in monitoring costs. The proposed 5 m × 1 m × 0.04 m sandpack model reveals that foam flooding enhances oil recovery by 15–20% via synergistic mechanisms of dynamic high-permeability channel plugging (governed by S=0.7C0.6kr−0.28) and mobility ratio optimization, surpassing the 30% recovery limit of conventional water flooding. The main controlling factors of gas channeling (injection speed, foam quality, permeability heterogeneity) are revealed, and the optimization of injection parameters, improvement of foam formulation, combined with numerical simulation and other synergistic techniques are proposed. The proposed large-scale physical simulation methods advance the understanding of foam flooding mechanisms in meter-scale heterogeneous reservoirs, directly guiding the optimization of air foam flooding operations in the Lukqin oilfield.