Abstract of Papers:-
PETRONAS Carigali Sdn Bhd, Sarawak Operations (PCSB SKO) operates predominantly
aged offshore pipelines principally for oil and gas evacuation in Sarawak Malaysia. By
implementing an integrated approach to pipeline integrity management comprising
rigorous inspections, fitness for service assessments and risk assessments; a risk based
asset integrity management programme has been developed which has enabled PCSB
to prioritize and optimize pipeline integrity management with the objective of
reducing incidents of pipeline failures and at the same time achieve life extension.
The predominant integrity threat for the pipeline assets has been microbial influence
corrosion (MIC). The integrity management programme implemented has enabled
PCSB SKO to assess the pipeline asset risks to MIC as well as prioritize and optimize the
internal corrosion mitigation programme.
An Integrated Approach to Managing the Integrity of Offshore Pipelines.
Mohamed Amin Abdullah
Head of Sarawak Operations
PETRONAS Carigali Sdn Bhd
7th APCE, 11th October 2011, Kuala Lumpur
Overview of PETRONAS Carigali Sarawak Operations (SKO) and its
Pipeline System
Primary Integrity Threats and Pipeline Condition Assessment
Strategy.
MIC Prediction
Integrity Management Approach - Detection and Mitigation Strategy
A Case Study
Summary and Conclusion
Source: Regional pipeline data
PCSB Sarawak Operation (SKO) involves in
managing predominantly aging pipeline assets
SKO Pipelines (1477km , 172 nos.)
Size
(in dia.)Up to 36
Age
(years)
< 20 20-30 > 30
47 58 67
PCSB Sarawak Operations operates about 1500 km of offshore pipelines
connected to Crude Oil Terminals in Miri and Bintulu
SKO Gas Customers
Helang Layang
B12B11
Laila
D21 D30
D18
Temana
D28
J4
D35
D16
Bayan
Hasnah
Lembuk
Sikau
Siwa
Fairley Baram
D51D5D26
D41
D12
D2
S. Acis
Singa Laut
Patricia
Sompotan
Serunai
Geduk
N. AcisE2
Gambang
Sapih
W. Lutong
Tukau
Bokor
Betty
ASAM PAYA
Fatimah
Merak
Beryl BaroniaBaram
Bakau
Mawar
Lemai
BINTULU
MCOT
MIRI
LUTONG
D34
MLNG
MLNG-TIGA
BCOT
Not to scale
MLNG DUA
TK/SI
F6
F13
E8
Sh. ClasticsE6
F28
E4
F23SW
E11R-C
E11R-B
E11R-AE11
JintanSerai
F23Cili Padi
M3M5G7
M4
F29
F12
F11F14
F9
Lada Hitam
Selasih
B.Sawi
Bijan
Bunga Pelaga
M1
F27F22
Saderi
Bokor South
Tukau Timur
Bakau Deep
Bario
J1
J5
J32
J2
K5
Tenggiri Marine
A21
A23
K4
BentaraBalai
J12Yu
C13
C2
Selar Marine
Jerong Marine
OBO
COB
COB
SarawakBrunei
SKO Crude Customers
ABF SMDS MLNG
Crude Oil Group (COG)
PC4
Kumang
PCPP – SK305 Block
Dana
CPIMS Enhancement
Corrosion Management
(product / process
monitoring, cleaning, inhi
bition / biociding)
Internal Inspection
External Inspection
Contingency material &
repair
Pipeline/facility
Rejuvenation and
replacement
What is MIC?
Microbial Influenced Corrosion (MIC): a
modified form of localised corrosion that
is enhanced by bacteria activity.
In crude oil and water injection pipelines,
Sulphate Reducing Bacteria (SRB) is a
primary source.
Growth and activity requires:
- Water
- An energy source (e.g. Light)
- A carbon source (e.g. CO2)
- An electron donor (e.g. organic /
inorganic substrate)
- An electron acceptor (e.g. SO4-, O2)
J Healy et all. Development of appropriate inspection and maintenance options to mitigate microbial induced corrosion (MIC) in offshore oil pipelines. 4th Annual Middle East Pipeline Integrity Management Summit, Abu Dhabi, 23-24 February 2009
Primary Threats are internal corrosion (sub-sea
pipelines) and external corrosion (risers)
Primary cause of internal corrosion attributed to MIC
This paper is focused on internal corrosion.
Typically the corrosion pits due
to MIC tend to be small (8 – 15
mm in diameter) and
hemispherical in shape.
Occurrence along pipeline can
be random (low points, areas
of low or stagnant flow) where
“biofilms” could be established
Recent experience of corrosion
rates (unmitigated) due to MIC
are in the range 0.5 to 6 mm/yr.
Premature pipeline failures
recorded (as early as 4 years
after installation)
SKO experienced very high corrosion rates
including failures due to MIC
ILI data showing Corrosion Growth
Rates of 0.5 to 3mm/yr
J Healy et all. Development of appropriate inspection and maintenance options to mitigate microbial induced corrosion (MIC) in offshore oil pipelines. 4th Annual Middle East Pipeline Integrity Management Summit, Abu Dhabi, 23-24 February 2009
Concentration of localised pits at the bottom of pipeline is
a typical pattern of MIC from internal Inspection (IP)
MIC associated with deep pitting and high corrosion growth rates – major implication on safe operation and remaining life prediction.
MIC on older assets (>25 years old) – experienced change in operations parameter, contamination of well and processing facilities.
Such assets traditionally designed for CO2 (sweet) corrosion with no cleaning & biocide treatment facilities.
Once established, MIC is difficult to control (no easy access to treat deep pits by cleaning and biocide dosing)
Low flow rates also a major issue in achieving effective cleaning / water removal and biocide treatment.
Structured approach to assess the MIC susceptibility
• Risk Assessment to prioritise high risk / criticalpipelines.
• Inspection & condition assessment.
• Integrity (FFS) Assessment / Root Cause Diagnosis
• Mitigation Strategy – to include feedback to enableeffectiveness of the Corrosion Management Plan(CMP) to be monitored and adjusted as appropriate.
• Pipeline Rejuvenation
MIC Prediction using monitored data has enabled quick
identification of affected pipelines for “treatment”
Sampling / Monitoring conducted for several of the field.
Relationship between available nutrients, bacteria counts,
other operational data and perceived risk established.
Key issues identified:
No water separation offshore
Water injection and well contamination
Recommendation for control / mitigation
BiDi OP brush tool + biocide.
Monitoring and condition assessment including
Inspection frequencies (IP & UT).
SKO Wide Risk Assessment is used to rank and
prioritize the pipelines for “treatment”
• Risk Assessment to prioritise high risk / critical pipelines.
• In-line Inspection to quantify the pipeline condition, risk level and extent of damage.
• Based on inspection data, evidence to diagnose (or otherwise) whether MIC is present
• Integrity (FFS) Assessment to define long term remedial and Corrosion Mitigation Strategy
• Rejuvenation to provide facilities for full CMP implementation.
• Options:
– In-line inspection along length of the pipeline
– UT inspection at local “high” risk areas?
• Techniques:
– Conventional in-line Ultrasonic's (UT) or Magnetic Flux Leakage (MFL)
– Tethered UT
– Localised subsea external UT
• Based on inspection data, evidence to diagnose whether MIC is present
• Immediate repair / investigation priorities is scheduled
• Based on available pipeline information, Corrosion Growth Rates can be estimated
• Operating conditions– Monitoring information – Corrosion modelling– Detailed comparison of
inspection data,
• Future repair priorities can be defined, together with revised Corrosion Management Plan (CMP).
Inspection 1
Inspection 2 Growth of Existing
Features
Growth of “New”
Feature
Inspection 1
Inspection 2 Growth of Existing
Features
Growth of “New”
Feature
A Case Study : 18” Crude Oil Pipeline.
• 18” x 55km crude oil line with a design life of 30 years
• In service since 1983 (19 years at time of first inspection 2002)
• Transport crude oil, water cut 17%, pH 6.86, CO2 1.27 mole%
• No inhibitor / biocide applied.
• Operational cleaning & water removal with Bi-Di tool conducted
monthly
• MIC Risk Assessment indicated HIGH risk level.
• First in-line inspection conducted in 2002 and repeat inspection
conducted in 2007 using IP and Calliper tools.
• Survey of Cathodic Protection system indicated that the pipeline was
adequately protected subsea.
IP result and its interpretation is used to
determine major internal corrosion threat.
• Re-inspection in 2007,
indicated significant increase
in internal corrosion features
(from 3,944 in 2002 to 26,276
in 2007) Deepest Feature
46%.
• Indicative of severe internal
corrosion activity over the 5
year inspection interval.
• 159 external features
reported, deepest 49%
located in the riser.
• Corrosion in riser associated
with transition from neoprene
riser coating to topside glass-
flake coating Distribution on internal corrosion features
49% @ 55,074.84m159External Corrosion Features
26,276 46% @ 28,699.84m
Deepest Feature
(%wt)
Internal Corrosion Features
49% @ 55,074.84m159External Corrosion Features
26,276 46% @ 28,699.84m
Deepest Feature
(%wt)
Internal Corrosion Features
• Significant and extensive corrosion reported at the
bottom of the line
• Although, sweet corrosion in the water phase has
contributed to the reported corrosion features but in
the current conditions (water cut, CO2) the expected
corrosion growth rate would be relatively low.
• MIC is suspected to have contributed to the
observed pitting in the line over the inspection
interval of 2002 to 2007.
FFS Assessment established the immediate
integrity and future inspection/maintenance plan
• FFS conducted using DNV RP-F101 Part B. Allowance for tool
tolerance included.
• All reported corrosion features found acceptable for Operation at
maximum allowable operating pressure (MAOP).
FFS Assessment established the future Inspection
and Maintenance Plan for the pipeline
• Based on determined corrosion
growth rates, 7 features were
predicted to require
investigation / repair within 4
years.
• Immediate Bi-Di cleaning and
inhibitor / biocide dosing was
recommended to addressed
MIC activity.
• Continued monitoring for MIC
activity, to determine
effectiveness of revised CMP.
• Re-inspection interval
proposed at 3 - 4 years, subject
to status of MIC control activity.
• Cost benefit analysis required
to justify upgrades to CMP and
repairs / reinspection strategy
versus pipeline replacement
SRB Trending
10
100
1000
10000
100000
1000000
Ju
l-0
7
Au
g-0
7
Se
p-0
7
Oct-
07
No
v-0
7
De
c-0
7
Ja
n-0
8
Fe
b-0
8
Ma
r-0
8
Ap
r-0
8
Ma
y-0
8
Ju
n-0
8
Ju
l-0
8
Au
g-0
8
Se
p-0
8
Oct-
08
No
v-0
8
De
c-0
8
Ja
n-0
9
Fe
b-0
9
Ma
r-0
9
Date
SR
B C
ou
nt
(ce
lls
/ml)
M MH H Inlet Outlet
Example of MIC Monitoring / trending
47.67
52.44 52.44 52.44 52.44 52.44
40
45
50
55
60
21-
Sep-
09
22-
Sep-
09
23-
Sep-
09
24-
Sep-
09
25-
Sep-
09
26-
Sep-
09
27-
Sep-
09
Dosage (
PP
M )
Date
Actual Dosage Of Corrosion Inhibitor Onsite Based on Water Production WLP-A (PL 339)
Recommended Dosage
(+15%)
from recommended
dosage(-15%)
fromrecommended
dosage
• MIC is a modified form of localised corrosion that is enhanced by the action of bacteria.
SKO have implemented a structured approach to identify and manage the risk of MIC, including:
SKO Wide Risk Assessment
Inspection and condition assessment
Integrity (FFS) Assessment
Development of appropriate mitigation actions including rejuvenation and replacement where required.
The approach adopted by SKO has enabled MIC to be managed effectively. This has enable SKO to implement an asset wide Pipeline Rejuvenation Program since 2009.
“Unless a man undertakes more than
he possibly can do, he will never do
all that he can”.
Henry Drummond
25
ThankYou
End of presentation