Eliminate failures of composite pipelines.
TRIAGE - Risk Assessment / Composite Pipelines positions operators to pin-point bad-actor well-pipeline combinations field ops can easily moderate well start-up ferocity to eliminate severe slugging that contributes to >80% of historical composite pipeline failures (gathering).
Future composite pipeline failures can be avoided.
1. PART 2
Integrity Hazard Classification for
Spooled Composite Pipelines
Severe Slug Flow at Well Start-up Events
Causes >80% of Composite Pipeline Failures
David Richardson, P.Eng.
(403) 880-2835
david@trustedpipelineadvisor.com
(Production Gathering)
3. Managing Pipeline Integrity –
Composite Pipelines
• TRIAGE - Risk Assessment / Composite Pipelines
• positions operators to pin-point bad-actor well-
pipeline combinations
• field ops can easily moderate well start-up ferocity
to eliminate severe slugging that contributes to
>80% of historical composite pipeline failures
(gathering)
• future composite pipeline failures can be avoided
4. 1 2 3 4 5 SUM PERCENT
5 378 101 37 6 64 586 6% RISK CLASS
4 381 77 80 12 174 724 7% 1258 35% SERIOUS
3 2455 428 222 43 385 3533 34% 1647 34% MODERATE
2 2492 490 132 29 204 3347 32% 7571 30% LOW
1 1675 353 82 24 152 2286 22% 10476 100% TOTAL
7381 1449 553 114 979
70% 14% 5% 1% 9%
SUM
PERCENT OF TOTAL
SEGMENT COUNT
Summary / Composites
Increasing Likelihood of Composite Failure
SEGMENT COUNT
Consequence
Business Loss
($)
TRIAGE – Integrity Hazard Service (Alberta) considers
exposure to severe cyclic slug flow (gathering)
• identifies bad-actor well-pipeline combinations
Risk Assessment - CompositesAlberta
October, 2020
10,476 Licensed Pipelines
Status = OperatingManaging Pipeline Integrity –
Composite Pipelines
6. Types of Slug Flow
• Hydrodynamic Slugs
• steady-state flow condition
• intermittent sequence of liquid plugs followed by
longer gas bubbles
• contributes to moderate pressure cycles within
the flowing pipeline
• in-situ water inventory remains constant
10,476 Licensed Pipelines
Status = Operating
8. Types of Slug Flow
• Terrain-Induced Slugs
• high-pressure / high-shear transient flow condition
• results in cyclic liquid unloading of in-situ stagnant
liquid from pipeline
10,476 Licensed Pipelines
Status = Operating
0.0 6.0 12.0 18.0 24.0
9. Types of Slug Flow
• Pigging Slugs
• one-time transient flow
condition
• slug volume = total
liquid in pipe minus
volume dumped into
the separator during
pig transit
10,476 Licensed Pipelines
Status = Operating
10. Types of Slug Flow
• Severe Slugging / Rate-Change Slugging
• short duration cyclic transient flow condition
• 5X – 25X production rate surges with
corresponding substantial pressure cycles
• short-duration / high-velocity slugging
10,476 Licensed Pipelines
Status = Operating
0.0 180.060.0 120.030.0 90.0 150.0
seconds
Pressure-kPa
1250.0
0.0
250.0
500.0
750.0
1000.0
#1 Cause of
Composite
Pipeline
Failures
12. • Severe slugging impacts the riser
causing unbalanced thrust forces
• forces act to “open-up” /
straighten the riser
• resultant axial stresses
contribute to critical upheaval
forces that rupture composite
pipelines at the riser
10,476 Licensed Pipelines
Status = Operating
Severe Slugging
Impact Forces
act to Straighten
the Riser
Implication of Severe
Slugging to the Integrity of
Composite Pipelines
Critical upheaval forces
are applied to composite
pipeline
13. 10,476 Licensed Pipelines
Status = Operating
• the “cap pressure” forces acting on the fixed steel
riser produce the force “S” that tends to push the
composite pipe in the upheaval direction
v, q, p
S
Implication of Severe
Slugging to the Integrity of
Composite Pipelines
Severe slugging induced by production surge
Composite pipeline
Steel pipeline / risers
S = applied longitudinal tensile stress (constrained for buried pipeline)
• unconstrained (surface) pipeline will elongate and bend (Bourdon Effect)
14. 10,476 Licensed Pipelines
Status = Operating
• Overburden forces prevent elongation of the composite
pipeline accentuating applied stress at riser connections
Implication of Severe
Slugging to the Integrity of
Composite Pipelines
v, q, p
S
v, q, p
Overburden load causes pipeline to resist tendency to elongate
Buried
Composite Pipeline
Axial Force
15. 10,476 Licensed Pipelines
Status = Operating
• Severe slugging translates into cyclic upheaval
buckling forces at riser connections
• cyclic applied forces cause fatigue failure of
fibers and eventual rupture of HDPE liner
v, q, p
S
Implication of Severe
Slugging to the Integrity of
Composite Pipelines
Cyclic upheaval buckling forces
cause rupture of composite
pipelines at riser connections
16. Conclusion #1
10,476 Licensed Pipelines
Status = Operating
• Most composite pipeline failures
(gathering) occur because of exposure to
excessive upheaval buckling forces at the
connection to steel risers attributed to
short-duration severe slugging at the time
of detrimental well start-up events
17. Conclusion #2
10,476 Licensed Pipelines
Status = Operating
• Moderating severe slugging during well
start-up events will eliminate nearly all
future composite pipeline failures in
production gathering service
• steady-state hydrodynamic slug flow is
not capable of creating critical
unbalanced forces at riser connections
18. 84% of reported failures can be re-classified as being caused by excessive
axial impact forces attributed to; severe cyclic slug flow or water hammer
10,476 Licensed Pipelines
544 Failure Events
Historical Failures Re-Classified
19. PART 3
Integrity Hazard Classification for
Spooled Composite Pipelines
Water Hammer Causes >80% of Composite
Pipeline Failures in Water Injection Service
David Richardson, P.Eng.
(403) 880-2835
david@trustedpipelineadvisor.com
