Investigation of Pressure Drop of Trapped Oil in Capillaries with Circular Cross-Sections

Abstract

An investigation is performed to determine the cause of the pressure drop for mobilizing a trapped oil slug in capillaries with circular cross-sections. This research is focused on pressure drop across the tube at different stages of oil mobilization and the physics behind the rapid decrease during slug separation. Pressure drop decease in the hold-up stage, which is too small to be observed experimentally, and the severe change of pressure drop during the slug detachment process are observed and quantitatively analyzed using computational fluid dynamics. The method used for the analysis is the equivalent viscosity model. For different slug lengths and multislug cases, the role of the capillary pressure difference in the process of trapped oil migration is well-recognized. The influence of oil dispersion in porous media on pressure drop when saturation is constant is also discussed. Compared with multislug pressure drops, the relative error of the equivalent viscosity model and computational fluid dynamic...