A Unified Mechanistic Model for Steady-State Two-Phase Flow in Wellbores and Pipelines

Abstract

Abstract A unified mechanistic model for the prediction of flow pattern, liquid holdup and pressure drop in wellbores and pipelines is presented. 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 stratified, slug, bubble, annular and dispersed bubble flow, applicable to the entire range of inclination angles, from horizontal (0°) to upward vertical flow (90°). The model can be applied to vertical wellbores, directional wells, horizontal wells, and pipelines, under normal production operation or artificial lift. The proposed model implements new criteria for eliminating discontinuity problems, providing smooth transitions between the different flow patterns. The new model has been initially validated against existing, various, elaborated, laboratory and field databases. Following the validation, the model is tested against a new set of field data, from the North Sea and Prudhoe Bay, Alaska, which includes 86 cases. The proposed model is also compared with other 6 most commonly used models and correlations. The model showed an outstanding performance for pressure drop prediction, with −1.3% average error, 5.5% absolute average error and 6.2 standard deviation. The proposed model provides the state-of-the-art of two-phase flow mechanistic modeling and design for the industry.