STUDY OF DIFFERENT METHODOLOGIES FOR INITIATION OF SLUG FLOW USING A LAGRANGIAN SLUG TRACKING MODEL

The slug flow regime is probably the prevailing pattern in the oil and gas industry, appearing in the nuclear industry as well. As a consequence, several studies have been conducted in order to understand the physics of this flow regime and to obtain a model to predict its properties. This work presents a transient hybrid methodology to simulate the gas-liquid slug regime in pipes with a change of direction from horizontal to downward inclined flow. The simulation initiates with a slug tracking model assuming the pipe to be filled with liquid, and follow the unit cells while they flow through the horizontal section; the information about the unit cells entering the pipe are obtained from experimental data. Near the elbow and beyond, the unit cells are simulated by a simplified two-fluid Lagrangian model, capable of providing flow details with the change of direction, and the dissipation of the slug flow to the stratified regime in a descendent slope. Simulations for a 4.862-m pipe were carried out, with the change of direction from horizontal to −3° and −5°. The results were compared to experimental data, showing that the model can successfully predict the flow behaviour for the given conditions.

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Numerical Simulation of Gas-Liquid Slug Flow Along Vertical Pipes Using the Slug Tracking Model

ASME-JSME-KSME 2011 Joint Fluids Engineering Conference: Volume 1, Symposia – Parts A, B, C, and D ◽

10.1115/ajk2011-10045 ◽

2011 ◽

Author(s):

Alex Pachas N. ◽

Ce´sar Perea M. ◽

Rigoberto E. M. Morales ◽

Cristiane Cozin ◽

Eugeˆnio E. Rosa ◽

...

Keyword(s):

Liquid Flow ◽

Slug Flow ◽

Momentum Balance ◽

Liquid Slug ◽

Wide Range ◽

Flow Intermittency ◽

Tracking Model ◽

Gas Liquid Flow ◽

Control Volumes ◽

Vertical Tubes

The intermittent gas-liquid flow, or slug flow, in vertical tubes occurs over a wide range of gas and liquid flow rates, with many applications, such as oil industry. Predicting the properties of this kind of flow is important to design properly pumps, risers and other components involved. In the present work, vertical upward slug flow is studied through a one-dimensional and lagrangian frame referenced model called slug tracking. In this model, the mass and the momentum balance equations are applied in control volumes constituted by the gas bubble and the liquid slug, which are propagated along the pipe. The flow intermittency is reproduced through the conditions at the entrance of the pipe, which are analyzed in statistical terms. These entrance conditions are given by a sequence of flow properties for each unit cell. The objective of the present work is to simulate the slug flow and its intermittency through the slug tracking model. The numerical results are compared with experimental data obtained by 2PFG/FEM/UNICAMP for air-water flow and good agreement is observed.

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Performance Analysis of the Slug Tracking Modeling for Intermittent Flows in Horizontal Pipes With Long Lengths

Volume 7: Fluids Engineering ◽

10.1115/imece2017-72479 ◽

2017 ◽

Author(s):

Bruna P. Naidek ◽

Marco G. Conte ◽

Cristiane Cozin ◽

Fausto A. A. Barbuto ◽

Rigoberto E. M. Morales

Keyword(s):

Slug Flow ◽

Numerical Models ◽

Solid Particles ◽

Frequency Variation ◽

Internal Diameter ◽

Liquid Slug ◽

Wake Effect ◽

Two Phase ◽

Industrial Enterprises ◽

Tracking Model

Two-phase gas-liquid slug flow is present in several industrial enterprises, especially in the oil industry where the flow of oil, gas and solid particles are frequent. Slug flow is characterized by the intermittent succession of a liquid slug followed by an elongated gas bubble. Some numerical models for the simulation of this flow pattern can be found in the literature. In this work, a slug tracking model is utilized. Simulations for horizontal flows of air and water in pipes with an internal diameter of 26 mm and lengths of up to 1500 m were performed, varying the inflow frequency of the bubbles in the pipe in all simulations so as to verify the influence of the frequency variation on the flow development,. The role of each correlation for the wake effect on the simulator was evaluated along the tube, and three comparisons between the obtained results were made, disregarding the wake effect and using the correlations proposed by Grenier (1997) and Rodrigues (2008). It was shown that the wake effect influences the time required for the flow to develop. In the analyses performed without the application of the wake effect, the flow developed and stabilized faster than when those correlations were applied.

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Three Phase Slug Tracking With PeTra

Part B: Offshore and Arctic Operations; Pipeline Technology; Production Technology; Tribology ◽

10.1115/etce2001-17065 ◽

2001 ◽

Cited By ~ 1

Author(s):

Marit Larsen ◽

Pål Hedne

Keyword(s):

Numerical Simulations ◽

Slug Flow ◽

Field Data ◽

Object Oriented ◽

Simulation Tool ◽

Moving Grid ◽

Fully Integrated ◽

Three Phase ◽

Tracking Model ◽

Object Oriented Methods

Abstract This paper presents numerical simulations of slug flow in multiphase pipeline systems using a novel simulation tool PeTra. The slug tracking scheme in PeTra is described. A major feature in PeTra is a moving grid together with a fully integrated front tracking scheme. The slug tracking model enables tracking of slug fronts with limited numerical diffusion. PeTra has been implemented in C++ using object-oriented methods resulting in a flexible and dynamic code. The numerical simulations are compared with experimental data and field data.

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Analysis of Numerical Simulation of Gas-Liquid Slug Flow Using Slug Tracking Model

Volume 7B: Fluids Engineering Systems and Technologies ◽

10.1115/imece2015-52031 ◽

2015 ◽

Author(s):

Stella C. P. Cavalli ◽

Cristiane Cozin ◽

Fausto A. A. Barbuto ◽

Rigoberto E. M. Morales

Keyword(s):

Slug Flow ◽

Oil And Gas ◽

Initial Conditions ◽

Computational Simulation ◽

Flow Simulation ◽

Gas Production ◽

Liquid Slug ◽

Two Phase ◽

Tracking Model ◽

Slug Flows

The distribution of the interfaces in gas-liquid two-phase flows in pipes can assume several shapes. Amongst those shapes, the slug flow pattern stands out as the most common one and occurs quite often in oil and gas production due to the flow rates and geometries used. This pattern is characterized by the succession of the so-called unit cells, that is, a flow structure composed of an aerated liquid slug and an elongated bubble surrounded by a liquid film. Due to its complexity, the study and understanding of this pattern’s behaviour becomes very important. The main methodologies used to describe slug flows are the steady-state one-dimensional models, based on the slug unit concept, and the transient approach, which takes the flow intermittence into account. The slug tracking model is one such transient approach, which considers slugs and elongated bubbles as separated bodies and analyzes the evolution along the flow and the interaction between those bodies. Whenever this model is numerically implemented, its initial conditions are important parameters that affect the results. The goal of this article is to study the influence of the initial conditions on slug flow simulation using the slug tracking model. A computer program written in Fortran95 using a slug tracking model to provide the characteristic parameters of slug flows such as the bubble and slug lengths and void fraction in the bubble region was built and used. The results were compared to experimental data and showed the important role the initial conditions play on the computational simulation of slug flow.

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