Modeling of Slug Dissipation and Generation in Gas-Liquid Hilly-Terrain Pipe Flow

Abstract

Hilly-terrain pipelines consist of interconnected horizontal, uphill and downhill sections. Slug flow experiences a transition from one state to another as the pipe inclination angle changes. Normally, slugs dissipate if the upward inclination becomes smaller or the downward inclination becomes larger, and slug generation occurs vice versa. Appropriate prediction of the slug characteristics is crucial for the design of pipeline and downstream facilities. In this study, slug dissipation and generation in a valley pipeline configuration (horizontal-downhill-uphill-horizontal) were modeled by use of the method proposed by Zhang et al. The method was developed from the unsteady continuity and momentum equations for two-phase slug flow by considering the entire film zone as the control volume. Computed results are compared with experimental measurements at different air-mineral oil flow rate combinations. Good agreement is observed for the change of slug body length to slug unit length ratio.

Slug flow models: Feasible domain and sensitivity to input distributions

“…To that end, models that track the front and back of individual slugs can be used to evaluate their characteristic lengths. For details on this approach, refer to the models of Al-Safran et al (2004) and Zhang et al (2003), which resort to the first principles for flow description. The unsteady velocity behavior of newly initiated slugs was investigated in Al-Safran et al (2013).…”

Understanding the Heat-Transfer Mechanism in the Steam-Assisted Gravity-Drainage (SAGD) Process and Comparing the Conduction and Convection Flux in Bitumen Reservoirs

“…The uneven seafloor topography results in hilly-terrain pipeline/riser systems. A hillyterrain pipeline consists of interconnected horizontal, downhill, and uphill sections (Zhang et al 2003). Although flow instabilities are relatively well understood for downward and horizontal pipeline/riser configurations (e.g., see Malekzadeh et al 2012b), there is still a lack of understanding of how flow characteristics change in a hilly-terrain pipeline/riser system.…”

Experimental Investigation of Three-Phase Gas-Oil-Water Slug Flow Evolution in Hilly-Terrain Pipelines

“…He observed slug flow behavior in a hilly-terrain pipeline, including generation of pseudo slugs at the horizontal/uphill elbow, variation of slug length along the pipeline, and existence of slug flow in the downhill section. In previous studies by Zhang et al (2003) and Al-Safran (2003) for two-phase hilly-terrain pipelines, the flow behavior in the elbow of the hilly-terrain section was coupled and analyzed with the flow conditions in the upstream downhill and downstream uphill sections of the hilly-terrain unit. Al-Safran et al (2005) also identified five different categories for slug dissipation in downhill section and slug initiation and growth in the uphill section of a hilly-terrain pipeline: (1) complete dissipation in the downhill section with slug initiation at the dip, (2) no hilly-terrain effect, (3) partial dissipation in the downhill section with initiation and growth at the dip, (4) no dissipation in the downhill section with initiation and growth at the dip, and (5) no dissipation in the downhill section with growth only at the dip.…”