Experimental and numerical study of residual oil mobilization under static and dynamic conditions

This thesis investigated the mechanism of mobilization for residual oil trapped in pore structures. A water-filled uniform circular capillary tube, with an oil slug trapped inside, employed as a simplified model for the experimental study. Water was injected into the capillary tube in order to mobilize the oil slug and the pressure difference across the capillary tube is measured during the process of mobilization. The pressure profile demonstrated the change of the pressure required for oil slug mobilization.;A series of mobilization experiments were carried out on the experimental model under vibratory stimulations to systematically study the influence of the vibration frequency and duration on trapped oil slug mobilization. Experimental results demonstrated that the required driving pressure decreases as the vibration frequency or duration increases, which indicates positive influences of these factors on residual oil mobilization.;Furthermore, numerical simulation was employed to study the flow behavior of the oil slug trapped in a capillary tube under different conditions. A numerical model was developed using a commercial computational fluid dynamics (CFD) software package to represent the experimental model in terms of its geometrical and physical properties. Numerical simulations were performed based on this model to study the development of water film during the process of mobilization, water film drainage and water film formation under the influence of vibratory stimulation. The visualized numerical results are qualitatively consistent with experimental observations. The numerical results are also in agreement with results presented in published research.;This research improves understanding of the mobilization of residual oil from a microscopic perspective. The research results provide important guidance to the exploration of the mechanisms of enhanced oil recovery (EOR) practice using vibro-seismic technique.;The thin water film between the oil slug and the capillary wall plays an important role in oil slug mobilization. The water film gradually drains out with time and this makes mobilization difficult. Experiments were conducted to investigate the relation between the driving pressure and drainage time. Experimental results based on oil slugs of different sizes revealed that the required driving pressure increases with the drainage time. When drainage time is sufficiently long, the required driving pressure reaches a stable level.