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 Riser Typical 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

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Phase 1: Kick-off April 2010

Phase 2: Completed 2014

Phase 3: Commenced 2014 ⇒ Schedule for completion Q1 2016

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Slug Loading and Response in Pipelines and Risers

⇒Global structural response

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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…

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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

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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 effects

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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

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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

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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.

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 review

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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 validation

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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

19 www.slarp-jip.com