Investigation of high-viscosity liquid two-phase flow pattern in horizontal and slightly inclined pipes

Heavy oil production and transport remains a challenge due to the lack of understanding of the flow behavior of gas and high viscosity oil two-phase flow in pipes. For example, existing two-phase flow in pipes mechanistic models shows significant discrepancy in predicting high-liquid-viscosity two-phase flow pattern transitions in horizontal and slightly inclined pipes. The objective of this study is to improve the modeling of stratified-smooth/ stratified-wavy flow pattern transition in horizontal and slightly inclined pipes for high-liquid-viscosity two-phase flow application. This objective is achieved by proposing a liquid viscosity-dependent sheltering coefficient model into the Taitel and Dukler (1976) stratified-smooth/stratified-wavy transition model. Further objective is to propose a new slug/annular transition criterion in horizontal and slightly inclined two-phase flow applicable for high-liquid-viscosity two-phase flow. A validation study of the proposed transition models is carried out against experimental high-liquid-viscosity two-phase flow pattern data sets. The validation result revealed that the proposed stratified-smooth/ stratified-wavy, and the slug/annular transition models predict the high viscosity horizontal flow pattern data more accurate than that of the original Taitel and Dukler (1976) model.