Slug catcher two-phase flow modeling and numerical simulations

In Oil & Gas applications, the use of pipelines that carry both liquid and gas phases of fuels extracted from on-shore and off-shore subsea wells is constantly growing. In these conditions, flow regimes such as slug flow and plug flow can appear. If these flow regimes are established, damage at the downstream devices, such as the treatment systems located at the end of the pipeline, can occur. It is therefore necessary to separate the phases before they are treated. The purpose of a slug catcher is to separate the phases at the exit of the pipeline and to send them separately to the respective treatment systems. In this paper, a series of fluid dynamic simulations using a CFD methodology to predict the separation performances of a typical finger-type slug catcher geometry are carried out. A typical geometry which resembles real installations is considered. Different computational models were tested to find the solution that would give more accurate results with the minimum computational effort. For this purpose, comparisons between static models (computationally less expensive) and transient models (more accurate) were carried out. The influence of different models of turbulence and the influence of the computational grid on the final results were also evaluated. Guidelines for the correct implementations of these kinds of simulations are reported and the impacts of modeling assumptions on the expected results are discussed. The main technical contributions of the paper are: • evaluating the operation of a slug catcher in different flow conditions; • testing the validation of the slug catchers by means of numerical simulations; • verifying the design choices in order to optimize the geometry of the slug catcher in relation to the conditions of use