Numerical Simulation Study on Bubble Rising Characteristics of Acidic Multi-Component in Vertical Wellbore

Abstract As global energy demand grows, the development of deep oil and gas resources is critical to increasing reserves and production. However, many deep gas reservoirs contain acidic gases such as hydrogen sulfide (H2S) and carbon dioxide (CO2). The intrusion of these gases into the wellbore can lead to blowouts due to formation and bottomhole pressure imbalances. In order to better understand the flow dynamics of the gas and liquid phases in the wellbore, this study explores the ascent characteristics of acidic multicomponent bubbles in a vertical wellbore using computational fluid dynamics (CFD) and species migration and fluid volume models. The accuracy of the model was first verified based on experimental data. Then, the study examined the effects of injection flow velocity and composition on bubble growth and migration. The results show that at the same injection flow velocity, the higher the H2S content in the bubbles, the lower their vertical rise velocity under the simultaneous effect of density and solubility. In addition, a feature map is introduced for rapid determination of bubble size at different gas intrusion velocity. This insight is valuable for understanding multiple flow patterns in the wellbore after gas intrusion occurs in sour gas reservoirs.