Lagrangian Three-phase Slug Tracking Methods

Abstract

The increasing amount of water produced from maturing oil and gas wells, and the growing need for development of smaller remote fields, puts higher requirements on accurate predictions of threephase flows in transport pipelines.

Several approaches may be followed to model these complex systems. One option is to perform simulations on a fixed computational grid, which is typically the method applied in commercial oil and gas multiphase flow simulators. Separated grid systems are then needed in order to implement slug tracking functionality.

An alternative approach is to carry out simulations on a moving computational grid, which is the method applied in this thesis. Here, the conservation equations and the slug tracking functionality use the same grid system. An existing two-phase Lagrangian slug tracking simulator has become subject to improvements and has been extended with three-phase simulation capability, which allows for water to be simulated as a third phase. The three-phase model formulation is based on a mixture liquid momentum formulation, where the relative velocity between the two liquid phases oil and water is described in terms of a slip velocity. Void in slugs, curved pipe geometry and a unit cell point model have also been included. The framework has been developed to handle all kinds of slip models, and should hence represent a convenient framework for testing and verification of slip models.