<p>Subsurface fluid flow behavior is a key factor that strongly influences hydrocarbon recovery rate and the field development efficiency. Tight sandstone, however, is characterized by very low porosity and permeability, and their heterogeneity makes fluid flow patterns within pore spaces more complex, and the tight sandstone oil–water interactions and microscopic flow mechanisms are only poorly understood. We thus examined the two-phase flow of oil–water and the microscopic distribution of residual oil in tight water-wet sandstone (in the Longdong area of the Ordos Basin) using physical experiments in conjunction with three-dimensional digital core technology. We imaged the fluid distribution within pore spaces at different displacement stages in 3D at high resolution using an in situ X-ray micro-computed tomography (micro-CT). Our findings revealed the oil phase primarily existing in a clustered and porous form during drainage; with the gradual flooding of brine, the oil phase gradually breaks up into droplets and membranes. Moreover, we quantified the residual oil saturation and its main distribution location, analyzing the distribution patterns of different oil phase morphologies during the different stages and their impact on oil recovery efficiency. Further, we found that the second imbibition stage significantly reduces the residual oil volume fraction within the pore space compared to first imbibition stage, thereby increasing the oil recovery efficiency. The results of this evaluation lead to a better understanding of the microscopic oil–water phase distribution in tight sandstone, which in turn will help to better optimize the hydrocarbon development plans.</p>