New Design Guidelines for Slug Loading

and Response in Pipelines and Risers

MCE Deepwater Development 2015, London

Slug Loading and Response

SLARP Phase 2 Testing

A-frame Supports

Lazy-S RiserTypical Riser Base Spool Problem

Slugging Problem Definition

Steady flow = Constant force

Slug flow = Time varying forces

− Varying fluid mass (heavy vs light)

− Varying fluid forces at bends

− Varying pressure, friction, Coriolis, etc.

Fatigue and overloading can occur

if slug flow is coupled with onerous

frequencies, dynamics and susceptible

configurations

3

Phase 1: Kick-off April 2010

Phase 2: Completed 2014

Phase 3: Commenced 2014

⇒ Schedule for completion Q1 2016

4

Slug Loading and Response

in Pipelines and Risers

⇒ Global structural response

1

2

3

Participation

Phase 1: Desktop Analysis

BP, BSEE, Chevron, ExxonMobil, Petrobras, Saipem,

Technip, Total, GE-Wellstream

Phase 2: Testing & Analysis

BP, BSEE, Chevron, ExxonMobil, Petrobras, Saipem,

Total, GE-Wellstream

Phase 3: Further Testing & Analysis

BP, Chevron, Saipem, Total

⇒ Confirmed to date…

5

Collaboration

Supported by a wide range of

collaborating organizations

Working together to achieve a

common GOAL

Establish industry consensus on

methodologies for analyzing structural

response of pipeline & riser

configurations subject to slug flow

6

Analytical formulation & methodologies

Communication of flow data

Global response to bend forces

Enhanced numerical modelling

Multi-planar configurations

Response coupling

Breakup & vertical flow

Viscosity effects

Resonance effects7

Phase 1

Phase 2(Testing)

Phase 3(Testing)

Targeted Uncertainties

Phase 2 Testing

4.5” horizontal U-piece

A-frame vertical supports

Single shot water slugs

8

Southwest Research

Institute (TX, USA)

− Wide range of slug velocities

(4 m/s to 15 m/s)

− Testing performed in air

− Slugs propelled using

Nitrogen from an inclined

loading beam

− Slug lengths between 20 m

and 30 m considered

− Various support conditions

Test Results and Findings

Enhanced numerical model developed to replicate

changing length & velocity of slugs

Excellent correlations achieved

9

Dynamic displacement of piping

system due to slug flow

Horizontal racking

displacement of U-piece

String potentiometer

for displacement

measurement

Numerical model

correlation

Physical Model vs Numerical Model

Pipe Displacement Time History

CFD correlation

SLARP Design Guideline

Problem Definition & Context

Latest Design Methodologies

Detailed Guidance on:

Flow data transfer (flow assurance to SURF)

Flow data assessment (qualitative & quantitative)

Iteration and optimization (analysis approach and configuration)

Monitoring of Structural Response

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SLARP Methodologies

Preliminary:

− Flow data sorted into groups

− Regular slug analysis performed for

representative slug units (regular train)

− Slug units can be fixed or variable

Intermediate:

− Detailed load definition (e.g. 4 hr

slug flow time history)

− Irregular slug train

− Random slug train

− Fixed or variable slug units

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Complex

− Coupled CFD-FEA

− Fluid structure interaction

− Demanding simulations

Intermediate Approaches

Slug Train Analogy…

Irregular slug train setup based on

specific flow assurance (FA)

simulation window

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Flow Assurance Input Data

Tabulated global input data

Liquid slug start times staggered as

per flow simulation window(s)

Regular Train = Consecutive identical units

Sample time history table - Time stamp example format:

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Slug Unit No.Entry Time

(s)

Liquid Slug Pocket (or Bubble)Slug Unit Velocity

(m/s)Length (m)Equivalent

Density (kg/m3)

Length (m)Equivalent

Density (kg/m3)

1 0 100 700 200 200 5

2 100 60 825 150 225 6

3 200 80 750 125 215 3

4 300 120 675 175 205 8

¦ ¦ ¦ ¦ ¦ ¦ ¦

¦ ¦ ¦ ¦ ¦ ¦ ¦

Populate table with all slug units identified in flow assurance prediction analysis window (e.g. 4 hrs, 12 hrs, 18 hrs)

e.g. 4 hrs

Irregular Slug Train

Each slug unit can be different

Different representative slug unit

velocities can be assigned to slug units

Train carriages can join,

separate & change length!

Variable slug units are also possible, i.e.:

Slug units can change properties during transit

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Slugging Fatigue Damage

First calculate for simulation window

e.g. 4 hrs, 8 hrs or 12 hrs

Then extrapolated to window of operation

e.g. 12 months

Compare to slugging fatigue budget

(or total calculation)

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Slugging?Other fatigue mechanisms

Phase 3 – Latest Scope of Work

Testing with continuous flow setup

Testing of multi-planar configuration

Numerical model correlation

SLARP Design Guideline update

Worked examples

Field data correlation study

Detailed monitoring system review16

Final details

being worked

Subject to final

participation

numbers

Summary

Summary

SLARP Design Guideline represents

a significant forward step as the 1st

collaborative industry guideline

relating to slug loading & response

methodologies in pipelines & risers

Successful correlation of full scale test

response results with numerical model

predictions for a range of conditions

Phase 3 (now ongoing) will significantly

expand current insights & model validation18

MCE DD 2015 – Thank You!

Presenter:

Jason Payne, Wood Group Kenny Ireland

Senior Project Manager – Technology Team

Jason.payne@woodgroupkenny.com

Co-authors:

− Adrian Connaire & Christian Chauvet, WGK

− Steven Green, Southwest Research Institute (SwRI)

Acknowledgments:

− SLARP JIP Participants - BP, BSEE, Chevron, ExxonMobil, GE-

Wellstream, Petrobras, Saipem, Technip, Total

19www.slarp-jip.com