Hydrodynamic study of multiphase flow transport of highly viscous foamy fluids

Abstract

Abstract Presence of multiple phases (oil, water, gas and sand) is very common in the oil industry, especially in the production of heavy crude oils. The complex behavior of this multiphase flow is aggravated by the significantly high viscosity of the oil at surface conditions. This phenomenon is frequently found in most Venezuelan heavy oil fields, which water is transported emulsified in oil with a gas fraction carried out as disperse bubbles into the liquid emulsion which is known as foamy oil, and other part of gas is a separate continuous phase generating different flow patterns in pipelines. Some efforts have been done in the hydrodynamics study of this type of multiphase flow mixtures. In order to understand how these systems behave, experimental data have been acquired for two-phase gas/oil and three-phase gas/oil/water mixtures flowing through horizontal pipes of 0.0243 m and 0.0508 m diameters, with 8.5 wt% of water and 1.5 wt% of a surfactant, pressures up to 255 kPa, temperature around 20 °C, superficial gas velocities between 0.92 and 17.56 m/s and superficial liquid velocities between 0.04 and 1.07 m/s, and oil viscosity of 0.43 Pa.s at the operational conditions. Three different flow patterns were obtained for the operational conditions: foamy slug flow, foamy stratified flow and foamy annular flow. Different models to predict flow pattern transitions were evaluated. It was found that the stratified – non stratified model of Brito et al. has good agreement with the experimental data used. For the slug-annular transition, the Taitel and Dukler model and the Barnea model tend to overestimate this transition while Brito et al. can be applied in both two-phase gas/oil and three-phase gas/oil/water systems for highly viscous liquids with the best match.