Sammendrag
Slug flow is a common flow regime in oil production, and the need for accurate physical models relevant for this regime is obvious. The most conventional method for slug flow modelling is the Unit Cell Model (UCM), where the flow is modelled in an averaged way as a series of slugs and slug bubbles with fully developed flow. Although this type of modelling is adequate for steady state predictions, the properties and behaviour of individual slugs can be important in dynamic situations, and this information is lost when applying the UCM modelling concept. This paper presents work performed on the slug capturing modelling approach developed in the LedaFlow project. Slug capturing is based on multi-field stratified flow transport equations, which are formulated and solved. With this technique waves and slugs are resolved on the computational grid using high-order numerical methods, eliminating the need for a sub-grid model such as the UCM. We demonstrate how the physical models have been improved to obtain the correct propagation velocity of slug bubbles, which is arguably the most important prerequisite for the success of any slug flow model. We further assess the performance of the prevailing slug capturing model using large scale experimental data at near-horizontal pipe inclinations. The main focus here is on two-phase flows, covering slug flow, stratified flow and the difficult pseudo-slug region. The purpose was to evaluate the fundamentals of the LedaFlow slug capturing model, in particular its ability to capture flow regime transitions and to model relatively small scale phenomena such as waves and small slugs. The results show that the slug capturing model is able to reproduce the experimental data well.