Unified mechanistic model for steady-state two-phase flow: Horizontal to vertical upward flow

A unified steady-state two-phase flow mechanistic model for the prediction of flow pattern, liquid holdup and pressure drop is presented that is appli cable to the range of inclination angles from horizontal(0 degrees) to upwa rd vertical how (90 degrees). The model is based on two-phase flow physical phenomena, incorporating recent developments in this area. It consists of a unified flow pattern prediction model and unified individual models for s tratified, slug, bubble, annular and dispersed bubble flow. The model can b e applied to vertical, directional and horizontal wells, and horizontal-nea r horizontal pipelines. The proposed model implements new criteria for elim inating discontinuity problems, providing smooth transitions between the di fferent flow patterns. The new model has been initially validated against existing, various, elabo rated, laboratory and field databases. Following the validation, the model is tested against a new set of field data, from the North Sea and Prudhoe B ay, Alaska, which includes 86 cases. The proposed model is also compared wi th six commonly used models and correlations. The model showed outstanding performance for the pressure drop prediction, with a -1.3% average error, a 5.5% absolute average error and 6.2 standard deviation. The proposed model provides an accurate two-phase flow mechanistic model for research and des ign for the industry.