14OTC 25107-Active Heating for Life of Field Flow Assurance

OTC 25107

Active Heating for Life of Field Flow Assurance

Paul McDermott & Ratnam Sathananthan,

Introduction

• Over the last 20 years subsea pipeline active heating technologies have been considered and utilised for the purpose of hydrate & wax prevention

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OTC 25107 • Active Heating for Life of Field Flow Assurance • Paul McDermott

• Two of the main flow assurance challenges in industry: Hydrate formation & Wax deposition

• Future Industry drivers: Developments in more remote areas (Arctic, West of Shetland, Deepwater GOM) and challenging fluid conditions

• A holistic approach combining thermal, hydraulic, chemical and mechanical methods.

Hydrate/Wax Management - Passive Thermal Control

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Normal Operation

• Well developed Industry techniques

Hydrate Management

Wax Management

Shutdown

Flowline Insulation

Chemical Injection

Cooldown time

Periodic pigging

Shallow Water: Depressurisation

Deepwater: Dead oil Displacement

Flowline Insulation

“No-touch” time

Chemical Injection

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Hydrate/Wax Management - Active Thermal Control

• Application of subsea pipeline heating systems offers: Control of system temperature at all stages of operation

Hydrate/Wax management strategies unconstrained by cooldown time

Greater operational flexibility across life of field

• Conventional solutions will no longer be adequate/cost effective

Pipeline Active Heating Methods

Hot Fluid Circulation Electrical Heating

Bundled Pipeline Systems

Pipe in Pipe Systems

Direct Electrical Heating

Indirect Electrical Heating

• Challenging developments becoming prevalent in industry;

Greater offset lengths (> 50km) Fluid & environmental conditions

Active Heating Systems Operating Philosophies

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• Operating Scenarios:

Temperature maintenance: low flowing/turndown conditions &/or planned/unplanned shutdown

Fluid warmup from ambient during restart

• Design Cases:

Hydrate Remediation

Wax Remediation – high WAT fluids (>40oC)

• Selection, design and operation of active heating systems across field life will be dictated by its requirement for use in:

Hot Water Circulation Systems

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• Heating mechanism: hot fluid circulation in Pipe-in-Pipe or Bundled Systems

Direct Heating Indirect Heating



Bundled Pipeline Systems Pipe in Pipe Systems Direct Electrical Heating Indirect Electrical Heating

• Technology successfully in operation for over 15 years

Hot Water Circulation Systems

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• Design considerations (Direct v Indirect): Heating Medium ΔP (Direct > Indirect)

Heating Medium Thermal Expansion

• Recent designs: Heating medium supplied by subsea produced water re-injection (Bacchus, 2011)

• Heating duty: Standalone heater/waste heat recovery system

Electrical Heating Systems

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• Direct: Pipeline wall heated from resistance to electrical current applied through it.




• Indirect: Use of separate series of cables to heat Pipeline wall

• Selection & Design: Maximise thermal efficiency by minimising system heat loss

Open Loop

Pipe in Pipe

Electrically Heat Traced Pipe-Pipe (ETH-PiP)

Main Technologies

Main Technology

Direct Electrical Heating (DEH) Systems

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Wet Insulated – Open Loop Dry Insulated - Pipe in Pipe




• Retrofit Open Loop DEH System Capability (Ormen Lange): Installed post installation in event of ice plug formation

• Robust designs with over 15 systems in operation (North Sea & GOM)

Electrically Heat Traced - Pipe in Pipe Systems

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• ETH-PiP maximises heating system performance by utilising:

Pipe in Pipe system - high performance insulation (U ≤ 1 W/m2/K) Low Power Trace heating cables




• Longer “no touch” times

• First ETH-PiP system piloted in Islay Field (2012)

• Thermal performance validated by JIP in 2001

• Track record:

Current Status of Active Heating Systems

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Active Heating System Longest current tie back distance Water Depths

Hot Water Circulation Systems In Operation -15km Bundled Pipeline -27km Dual Flowline PiP Recent study shown bundle solution to be technically feasible at a distance of 50km

- 1670m (King PiP system)- Bundles installed to depth

of 410m

Direct Electrical Heating - 44km in operation (Tyrihans)- 55km – in development for

North Sea

- 1000m – PiP Systems (In operation)

- 1070m - Open Loop (In development for West Africa field)

ETH-PiP - 6km (Successful Islay Pilot Scheme in North Sea)

- 14km (In development for West Africa field)

- 700m (In development for West Africa)

Future Trends For Active Heating Systems

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• Trends from Past, Present and Future?

Summary

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• Past to Present: Over last 15 years heating systems have evolved from a novel technology to more commonly and robustly used.

• Continued technology innovation & qualification: ensure heating systems may be integrated with other developing technologies to meet future industry flow assurance challenges.

• Future: Crucial component in life of field flow assurance strategies for common future subsea production systems with much longer step out distances and challenging fluid/environmental conditions.

• Next evolution of active heating systems: Deployment of Electrical Trace Heating Pipe in Pipe systems – low power and high system thermal performance.

Acknowledgements / Thank You / Questions

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Documents

14OTC 25107-Active Heating for Life of Field Flow Assurance