seminar - técnico lisboa - autenticação · pdf filecase-studies:...

May, 2014

Ana Sousa 51968

Seminar

Outline

What is Multiphase Flow?

Case-studies. Liquid-Gas Flows:

Flow Pattern

Some Practical Solutions

Challenges involving flow assurance

Vertical Two-Phase Flow

Horizontal Two-Phase Flow:


Case-studies: Liquid-Gas Flows


Some Practical

Solutions

Interacting flow of two or more phases, where the interface

between the phases is influenced by their motion

Oil

Water

Gas

Flow Assurance

Importance of studding multiphase flow:

• Need to optimum design

• Prediction of operational limits

• Safety of plant operation




Some Practical

Solutions

Multiphase flow

• The number of the variables affecting the pressure drop is enormous:

thermodynamics parameters and variables describing the interaction

between the phases.

• Compressibility - density depends on the actual flowing pressure and

temperature.

• Frictional pressure losses are much more difficult to describe, since more

than one phases is in contact with the pipe wall.

• Slippage loss - The great difference in densities of the liquid and gas

phases and the tendency of the gas phase to overtake or slip-by the

liquid phase.

• Pressure losses considerably vary with the spatial arrangement in the

pipe of the flowing phases

Challenge in multiphase flow - To predict the pressure drop along the pipe.

Flow Assurance

Vertical Two-Phase Flow

…

Bubble flow Slug flow Churn flow Annular flow Wispy Annular

Bubble Flow - the liquid is continuous and there is a dispersion of bubbles

within the liquid;

Slug or Plug Flow - the bubbles have coalesced to make larger bubbles

which approach the diameter of the tube;

Churn Flow - the slug flow bubbles have broken down to give oscillating

churn regime;

Annular Flow - the liquid flows on the wall of the tube as a film, with some

liquid entrained in the core, and the gas flows in the centre;

Wispy Annular Flow - as the liquid flow rate is increased, the concentration

of drops in the gas core increases, leading to the formation of large lumps or

streaks (wisps) of liquid.



Some Practical

Solutions

Flow Assurance

Video

http://www.thermopedia.com/content/8/






Escoamento_Vertical.wmv

Horizontal Two-Phase Flow

Bubble flow

Annular flow

Elongated bubble flow (Plug)

Slug flow

Stratified flow

Stratified wavy flow

Stratified Flow - the gravitational separation is complete;

Stratified Wavy Flow - the surface becomes unstable and waves appear on it;

Elongated Bubble Flow - large bubbles flowing near the top of the tube;



Some Practical

Solutions

Incre

asin

g f

low

speed

Flow Assurance




Definition of Flow Pattern

…



Some Practical

Solutions

Flow Assurance

Horizontal Two-Phase Flow Pattern

Challenges involving Flow Assurance

Emulsions

Slugging

Sand

Hydrates

Wax / Paraffin deposition

Scale

Fluid control

Flow control



Flow Assurance

Some Practical

Solutions

Slugs

Asphaltenes

Wax

Scales

Hydrates

Corrosion



Some Practical

Solutions

Flow Assurance

Challenges involving Flow Assurance

Some Practical Solutions to Assure Flow

Problem Solution

Asphaltenes Asphaltenes inhibitors

Scales Inhibitors and pigging.

Hydrates Hydrates inhibitors

Wax 1. Hot oiling for flow line cleanup can be cost

effective if the paraffin is totally removed and

stays in solution in the oil used at separator

temperature.

2. Regular pigging

3. Solvent or condensate treatments

4. Chemicals can be applied

Corrosion To cool the fluids prior to entry to the pipeline. An

alternative is to use corrosion resistant pipe for

the initial sections of the pipeline



Some Practical

Solutions

Flow Assurance

Problem Solution

Slugs Slug avoidance:

Heavy slugging can be avoided by design or

operational changes. Smaller diameter pipelines

can reduce slugging;

Another solution often used on-shore is to install

a big slug catcher at the receiving facilities.

Slug control:

Active use of the topside choke;

Artificial gas-lift

Increase gas injection on the well;



Some Practical

Solutions

Flow Assurance

Some Practical Solutions to Assure Flow

12

References: 1. Barnea, D. (1987) A unified model for predicting flow-pattern transitions for

the whole range of pipe inclinations, Int. J. Multiphase Flow, 13, 1-12.

2. Dukler, A. E. and Taitel, W. (1986) Flow Pattern Transitions in Gas-Liquid

Systems: Measurement and Modelling, Chapter 1 of Multiphase Science and

Technology, Vol. 2 (Ed. G. F. Hewitt, J. M. Delhaye and N. Zuber),

Hemisphere Publishing Corporation.

3. Hewitt, G. F. (1982) Chapter 2, Handbook of Multiphase Systems (Ed.

G. Hetsroni), Hemisphere Publishing Corporation, New York.

4. Hewitt, G. F., Martin, C. J. and Wilkes, N. S. (1985) Experimental and

modelling studies of annular flow in the region between flow reversal and the

pressure drop minimum, Physico-Chemical Hydrodynamics, 6, 43-50.

5. Lin, P. Y. and Hanratty, T. J. (1986) Prediction of the initiation of slugs with

linear stability theory, Int. J. Multiphase Flow, 12, 79-98.

6. Taitel, Y., Barnea, D. and Dukler, A. E. (1980) Modelling flow pattern

transitions for steady upward gas-liquid flow in vertical tubes, AIChE J, 26,

345-354.

7. Bratland O. (2009) Pipe Flow 2 – Multiphase Flow Assurance

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