Development of Two-Fluid Flow Model for Pipeline Decompression

2002 ◽  
Author(s):  
X. L. Zhou ◽  
R. G. Moore ◽  
G. G. King
Keyword(s):  
Fluid Flow ◽  
Natural Gas ◽  
Flow Model ◽  
Transient Flow ◽  
Mechanical Performance ◽  
Second Law Of Thermodynamics ◽  
Two Phase ◽  
Natural Gas Pipelines ◽  
Time Space ◽  
Two Fluid

Natural gas pipelines have an excellent safety record but on rare occasions they rupture and decompress. When this happens their contents cool rapidly and form two phases. The decompression behaviors of multiphase fluid released from pipeline are not well understood. Pipeline decompression modeling is useful in characterizing the rapid transient flow that occurs when a pipeline ruptures. Numerical simulation can provide detailed data for analyzing the consequences of pipeline bursts and the mechanical performance of pipelines as they decompress. Decompression behavior of fluids is complicated by the formation of two-phase flow due to gas cooling or liquid flashing effects. Based on the time-space-ensemble composite averaging procedure, a two-fluid flow model is derived for simulating high-pressure natural gas pipeline decompression. The composite averaging operator is supported and demonstrated by simple experimental data. A set of constitutive equations is formulated for the closure of the system of equations. The conservation equations along with closure equations are examined for compliance with the second law of thermodynamics. Characteristics analysis is performed to ensure that the set of equations is well-posed mathematically.

A Unified Two-Fluid Model for Multiphase Flow in Natural Gas Pipelines

2002 ◽  
Author(s):  
Luis F. Ayala ◽  
Eltohami S. Eltohami ◽  
Michael A. Adewumi
Keyword(s):  
Natural Gas ◽  
Hydrodynamic Model ◽  
Fluid Model ◽  
Liquid Loading ◽  
Two Phase ◽  
Natural Gas Pipelines ◽  
Fluid Velocities ◽  
Two Fluid Model ◽  
Two Fluid ◽  
Equilibrium Calculations

A unified two-fluid model for multiphase natural gas and condensate flow in pipelines is presented. The hydrodynamic model consists of steady-state one-dimensional mass and continuity balances for each phase and a combined energy equation to give a system of five first-order ordinary differential equations. The hydrodynamic model is coupled with a phase behavior model based on the Peng-Robinson equation of state to handle the vapor-/liquid equilibrium calculations and thermodynamic property predictions. The model handles single and two-phase flow conditions and is able to predict the transition between them. It also generates profiles for pressure, temperature, and the fluid velocities in both phases as well as their holdups. The expected flow patterns as well as their transitions are modeled with emphasis on the low liquid loading character of such systems. The expected flow regimes for this system are dispersed liquid, annular-mist, stratified smooth as well as stratified wavy.

Numerical Investigation on Multiphase Erosion-Corrosion Problem of Steel of Apparatus at a Well Outlet in Natural Gas Production

2018 ◽  
Vol 140 (12) ◽  
Author(s):  
Zhang Jianwen ◽  
Jiang Aiguo ◽  
Xin Yanan ◽  
He Jianyun
Keyword(s):  
Fluid Flow ◽  
Natural Gas ◽  
Production Rate ◽  
Gas Production ◽  
Two Phase ◽  
Gas Well ◽  
Chemical Corrosion ◽  
High Production Rate ◽  
Erosion Corrosion ◽  
Corrosion Problem

The erosion-corrosion problem of gas well pipeline under gas–liquid two-phase fluid flow is crucial for the natural gas well production, where multiphase transport phenomena expose great influences on the feature of erosion-corrosion. A Eulerian–Eulerian two-fluid flow model is applied to deal with the three-dimensional gas–liquid two-phase erosion-corrosion problem and the chemical corrosion effects of the liquid droplets dissolved with CO2 on the wall are taken into consideration. The amount of erosion and chemical corrosion is predicted. The erosion-corrosion feature at different parts including expansion, contraction, step, screw sections, and bends along the well pipeline is numerically studied in detail. For dilute droplet flow, the interaction between flexible water droplets and pipeline walls under different operations is treated by different correlations according to the liquid droplet Reynolds numbers. An erosion-corrosion model is set up to address the local corrosion and erosion induced by the droplets impinging on the pipe surfaces. Three typical cases are studied and the mechanism of erosion-corrosion for different positions is investigated. It is explored by the numerical simulation that the erosion-corrosion changes with the practical production conditions: Under lower production rate, chemical corrosion is the main cause for erosion-corrosion; under higher production rate, erosion predominates greatly; and under very high production rate, erosion becomes the main cause. It is clarified that the parts including connection site of oil pipe, oil pipe set, and valve are the places where erosion-corrosion origins and becomes serious. The failure mechanism is explored and good comparison with field measurement is achieved.

Development of a Numerical Model for Single- and Two-Phase Flow Simulation in Perforated Porous Media

2019 ◽  
Vol 142 (4) ◽  
Author(s):  
Hamed Movahedi ◽  
Mehrdad Vasheghani Farahani ◽  
Mohsen Masihi
Keyword(s):  
Porous Media ◽  
Fluid Flow ◽  
Transient Flow ◽  
Accurate Determination ◽  
Flow Simulation ◽  
Velocity Profiles ◽  
Geometrical Parameters ◽  
Reservoir Properties ◽  
Two Phase ◽  
Phase Fluid

Abstract In this paper, we present a computational fluid dynamics (CFD) model to perform single- and two-phase fluid flow simulation on two- and three-dimensional perforated porous media with different perforation geometries. The finite volume method (FVM) has been employed to solve the equations governing the fluid flow through the porous media and obtain the pressure and velocity profiles. The volume of fluid (VOF) method has also been utilized for accurate determination of the volume occupied by each phase. The validity of the model has been achieved via comparing the simulation results with the available experimental data in the literature. The model was used to analyze the effect of perforation geometrical parameters (length and diameter), degree of heterogeneity, and also crushed zone properties (permeability and thickness) on the pressure and velocity profiles. The two-phase fluid flow around the perforation tunnel under the transient flow regime was also investigated by considering a constant mass flow boundary condition at the inlet. The developed model successfully predicted the pressure drop and resultant temperature changes for the system of air–water along clean and gravel-filled perforations under the steady-state conditions. The presented model in this study can be used as an efficient tool to design the most appropriate perforation strategy with respect to the well characteristics and reservoir properties.

Nonlinear studies of tumor morphological stability using a two-fluid flow model

2018 ◽  
Vol 77 (3) ◽  
pp. 671-709 ◽  
Author(s):  
Kara Pham ◽  
Emma Turian ◽  
Kai Liu ◽  
Shuwang Li ◽  
John Lowengrub
Keyword(s):  
Fluid Flow ◽  
Flow Model ◽  
Morphological Stability ◽  
Two Fluid

Dynamic Simulation of Gas-Liquid Homogeneous Flow in Natural Gas Pipeline Using Two-Fluid Conservation Equations

2005 ◽  
Author(s):  
Mohammad Abbaspour ◽  
Kirby S. Chapman ◽  
Larry A. Glasgow ◽  
Zhongquan C. Zheng
Keyword(s):  
Natural Gas ◽  
Large Time ◽  
Gas Pipeline ◽  
Phase Flow ◽  
Time Step ◽  
Two Phase ◽  
Natural Gas Pipeline ◽  
Fully Implicit ◽  
Large Time Step ◽  
Two Fluid

Homogeneous two-phase flows are frequently encountered in a variety processes in the petroleum and gas industries. In natural gas pipelines, liquid condensation occurs due to the thermodynamic and hydrodynamic imperatives. During horizontal, concurrent gas-liquid flow in pipes, a variety of flow patterns can exist. Each pattern results from the particular manner by which the liquid and gas distribute in the pipe. The objective of this study is to simulate the non-isothermal, one-dimensional, transient homogenous two-phase flow gas pipeline system using two-fluid conservation equations. The modified Peng-Robinson equation of state is used to calculate the vapor-liquid equilibrium in multi-component natural gas to find the vapor and liquid compressibility factors. Mass transfer between the gas and the liquid phases is treated rigorously through flash calculation, making the algorithm capable of handling retrograde condensation. The liquid droplets are assumed to be spheres of uniform size, evenly dispersed throughout the gas phase. The method of solution is the fully implicit finite difference method. This method is stable for gas pipeline simulations when using a large time step and therefore minimizes the computation time. The algorithm used to solve the nonlinear finite-difference thermo-fluid equations for two phase flow through a pipe is based on the Newton-Raphson method. The results show that the liquid condensate holdup is a strong function of temperature, pressure, mass flow rate, and mixture composition. Also, the fully implicit method has advantages, such as the guaranteed stability for large time step, which is very useful for simulating long-term transients in natural gas pipeline systems.

A Method of Limiting Intermediate Values of Volume Fraction in Iterative Two-Fluid Computations

1982 ◽  
Vol 24 (4) ◽  
pp. 221-224 ◽  
Author(s):  
M. B. Carver
Keyword(s):  
Fluid Flow ◽  
Computational Analysis ◽  
Volume Fraction ◽  
Simultaneous Solution ◽  
Two Phase ◽  
Upper Limit ◽  
Satisfactory Method ◽  
Iterative Procedures ◽  
Physical Reasons ◽  
Two Fluid

Multidimensional computational analysis of fluid flow is usually done by segmented iterative methods, as the equations sets generated are too large to permit simultaneous solution. Frequently the need arises to compute values for variables which must remain bounded for physical reasons. In two-phase computation, for example, the volume fraction is restricted to values between 0 and 1, but iterative procedures often return intermediate values which violate these bounds. It is fairly straightforward to prevent negative values, however no satisfactory method of imposing the upper limit has been published. A method of smoothly applying the limit in reversible fashion is outlined in this note.

Evaluation of “Marching Algorithms” in the Analysis of Multiphase Flow in Natural Gas Pipelines

2008 ◽  
Vol 130 (4) ◽  
Author(s):  
Luis F. Ayala ◽  
Doruk Alp
Keyword(s):  
Natural Gas ◽  
Multiphase Flow ◽  
Fluid Dynamic ◽  
Standard Technique ◽  
Rate Of Change ◽  
Entire Length ◽  
Governing Equations ◽  
Two Phase ◽  
Natural Gas Pipelines ◽  
Common Technique

Marching algorithms are the rule rather than the exception in the determination of pressure distribution in long multiphase-flow pipes, both for the case of pipelines and wellbores. This type of computational protocol is the basis for most two-phase-flow software and it is presented by textbooks as the standard technique used in steady state two-phase analysis. Marching algorithms acknowledge the fact that the rate of change of common fluid flow parameters (such as pressure, temperature, and phase velocities) is not constant but varies along the pipe axis while performing the integration of the governing equations by dividing the entire length into small pipe segments. In the marching algorithm, governing equations are solved for small single sections of pipe, one section at a time. Calculated outlet conditions for a particular segment are then propagated to the next segment as its prescribed inlet condition. Calculation continues in a “marching” fashion until the entire length of the pipe has been integrated. In this work, several examples are shown where this procedure might no longer accurately represent the physics of the flow for the case of natural gas flows with retrograde condensation. The implications related to the use of this common technique are studied, highlighting its potential lack of compliance with the actual physics of the flow for selected examples. This paper concludes by suggesting remedies to these problems, supported by results, showing considerable improvement in fulfilling the actual constraints imposed by the set of simultaneous fluid dynamic continuum equations governing the flow.

A modeling and analytical solution for transient flow in natural gas pipelines with extended partial blockage

2015 ◽  
Vol 22 ◽  
pp. 141-149 ◽  
Author(s):  
Zongming Yuan ◽  
Zhibin Deng ◽  
Maoze Jiang ◽  
Ying Xie ◽  
Yue Wu
Keyword(s):  
Natural Gas ◽  
Analytical Solution ◽  
Transient Flow ◽  
Gas Pipelines ◽  
Natural Gas Pipelines
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