OTC 25107
Active Heating for Life of Field Flow Assurance
Paul McDermott & Ratnam Sathananthan,

Introduction
• Two of the main flow assurance challenges in
industry: Hydrate formation & Wax deposition
• A holistic approach combining thermal,
hydraulic, chemical and mechanical methods.
• Over the last 20 years subsea pipeline active
heating technologies have been considered and
utilised for the purpose of hydrate & wax
prevention
Slide 2
• Future Industry drivers: Developments in more remote areas (Arctic,
West of Shetland, Deepwater GOM) and challenging fluid conditions
OTC 25107 • Active Heating for Life of Field Flow Assurance • Paul McDermott

Slide 3
Hydrate/Wax Management - Passive Thermal Control
• Well developed Industry techniques
Normal Operation
OTC 25107 • Active Heating for Life of Field Flow Assurance • Paul McDermott
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

Slide 4
Hydrate/Wax Management - Active Thermal Control
• Challenging developments becoming prevalent in industry;
• Conventional solutions will no longer be adequate/cost effective
• 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
Pipeline Active Heating Methods
Hot Fluid Circulation Electrical Heating
OTC 25107 • Active Heating for Life of Field Flow Assurance • Paul McDermott
Bundled Pipeline
Systems
Pipe in Pipe
Systems
Direct Electrical
Heating
Indirect Electrical
Heating
 Greater offset lengths (> 50km)
 Fluid & environmental conditions

Active Heating Systems Operating Philosophies
Slide 5
• Selection, design and operation of active heating systems across field
life will be dictated by its requirement for use in:
OTC 25107 • Active Heating for Life of Field Flow Assurance • Paul McDermott
• 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)

Hot Water Circulation Systems
Slide 6
Pipeline Active Heating Methods
Hot Fluid Circulation Electrical Heating
Bundled Pipeline
Systems
Pipe in Pipe Systems Direct Electrical Heating Indirect Electrical Heating
• Heating mechanism: hot fluid circulation in Pipe-in-Pipe or Bundled
• Technology successfully in operation for over 15 years
OTC 25107 • Active Heating for Life of Field Flow Assurance • Paul McDermott
Systems
 Direct Heating  Indirect Heating

Hot Water Circulation Systems
Slide 7
• Design considerations (Direct v Indirect):
 Heating Medium ΔP (Direct > Indirect)
 Heating Medium Thermal Expansion
• Heating duty: Standalone heater/waste heat recovery system
• Recent designs: Heating medium
supplied by subsea produced water re-injection
OTC 25107 • Active Heating for Life of Field Flow Assurance • Paul McDermott
(Bacchus, 2011)

Electrical Heating Systems
Slide 8
• Direct: Pipeline wall heated from resistance to electrical current applied
OTC 25107 • Active Heating for Life of Field Flow Assurance • Paul McDermott
through it.
Pipeline Active Heating Methods
Hot Fluid Circulation Electrical Heating
Bundled Pipeline
Systems
Pipe in Pipe
Systems
Direct Electrical Heating Indirect Electrical Heating
• 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
Slide 9
Pipeline Active Heating Methods
Hot Fluid Circulation Electrical Heating
Bundled Pipeline Systems Pipe in Pipe Systems Direct Electrical Heating Indirect Electrical Heating
 Wet Insulated – Open Loop  Dry Insulated - Pipe in Pipe
• Robust designs with over 15 systems in operation (North Sea & GOM)
• Retrofit Open Loop DEH System Capability (Ormen Lange):
 Installed post installation in event of ice plug formation
OTC 25107 • Active Heating for Life of Field Flow Assurance • Paul McDermott

Electrically Heat Traced - Pipe in Pipe Systems
Slide 10
Pipeline Active Heating Methods
Hot Fluid Circulation Electrical Heating
Bundled Pipeline Systems Pipe in Pipe Systems Direct Electrical Heating Indirect Electrical Heating
• 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
• Track record:
• Thermal performance validated by
JIP in 2001
• First ETH-PiP system piloted in Islay
Field (2012)
OTC 25107 • Active Heating for Life of Field Flow Assurance • Paul McDermott

Current Status of Active Heating Systems
Slide 11
Active Heating System Longest current tie back distance Water Depths
OTC 25107 • Active Heating for Life of Field Flow Assurance • Paul McDermott
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
Slide 12
ETH PiP DEH HWC
OTC 25107 • Active Heating for Life of Field Flow Assurance • Paul McDermott
40
35
30
25
20
15
10
5
0
1999 2005 2013 2040
No. in Operation
Year
Deep Water Long
Distance Smart
Fields in Operation
is common place
with substantial
experience in use
of:
Low power high
thermal
performance ETH
PiP technology
utilising
monitoring
systems to
improve system
performance
• Trends from Past, Present and Future?

Summary
Slide 13
• Past to Present: Over last 15 years heating systems have evolved
from a novel technology to more commonly and robustly used.
• Next evolution of active heating systems: Deployment of Electrical
Trace Heating Pipe in Pipe systems – low power and high system
thermal performance.
• 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.
• Continued technology innovation & qualification: ensure heating
systems may be integrated with other developing technologies to
meet future industry flow assurance challenges.
OTC 25107 • Active Heating for Life of Field Flow Assurance • Paul McDermott

Acknowledgements / Thank You / Questions
Slide 14