running in a new platform
TRANSCRIPT
Running-in a new platform!When the real world does not obey your design basis
Martin Olldag BayLeif BlidegnDONG E&P
Geilo 28 March
Content
The Siri Complex
Design basis and expected challenges
CO2 Corrosion
Scaling Real-life and unexpected challenges
Deviations in flowrates and temperature Compressor performance
Wax precipitation Severe slugging
Conclusion
The Siri Complex
A
56095607 5608
B
5606
D
55095508
C
0002
5507
5605
5505 5506
B
0003
A
5604
5504
E
039
570957080009 00100008 5707
0004
0011
5610
5603
5510
5503
031
5706
5710
0005
0012
038
0001
030
F
0007
Projection: Mercator (world) [not to scale]
Operator
DONG Energy
Hess
Mærsk
Fields
Gas
Gas Condensate
Gas & Oil
Oil
Oil & Gas
4° 6°
56°
Nini ØstNini Vest Nini
SofieStine Segment-2
Stine Segment-1SiriSiri Nord
ConnieFrancisca
Cecilie
RauLulita
Harald
Amalie
Svane
Hejre
Svend
Q1Syd Arne
Bertel
Kim
Gert
RavnElly
ValdemarAdda
Roar
RolfDagmar
Gorm
HalfdanLola
TyraTyra Sydøst
Halfdan/NESkjold
Dan AlmaKraka
Regnar
4/956/95
16/9813/061/907/869/95
4/981/06
5/98
14/06 7/892/06
NorwegianShelf
DanishShelf
BritishShelf
DutchShelf
GermanShelf
3/07
8°
The Siri Complex
Nini
Cecilie Siri
10" Water Injection
6/10" Water Injection
4" Gas lift
4" Gas lift12" Multiphase
8" Multiphase
Stine S1
Umbilical
Nini East
NiniNini
CecilieCecilie SiriSiri
10" Water Injection
6/10" Water Injection
4" Gas lift
4" Gas lift12" Multiphase
8" Multiphase
Stine S1
Umbilical
Nini EastNini East
The Siri Complex
Siri Wellhead and process platform First oil March 1999 Tank capacity 40.000 m3
Bed capacity 60 pers. Weight 11.000 Tonnes Reinjection > 95% Design capacity 50.000 barrels/day
The Siri Complex
Nini
Cecilie Siri
10" Water Injection
6/10" Water Injection
4" Gas lift
4" Gas lift12" Multiphase
8" Multiphase
Stine S1
Umbilical
Nini East
NiniNini
CecilieCecilie SiriSiri
10" Water Injection
6/10" Water Injection
4" Gas lift
4" Gas lift12" Multiphase
8" Multiphase
Stine S1
Umbilical
Nini EastNini East
The Siri Complex
Nini
Cecilie Siri
10" Water Injection
6/10" Water Injection
4" Gas lift
4" Gas lift12" Multiphase
8" Multiphase
Stine S1
Umbilical
Nini East
NiniNini
CecilieCecilie SiriSiri
10" Water Injection
6/10" Water Injection
4" Gas lift
4" Gas lift12" Multiphase
8" Multiphase
Stine S1
Umbilical
Nini EastNini East
The Siri Complex
Stine Segment 1 Subsea template First oil May 2004
The Siri Complex
Nini
Cecilie Siri
10" Water Injection
6/10" Water Injection
4" Gas lift
4" Gas lift12" Multiphase
8" Multiphase
Stine S1
Umbilical
Nini East
NiniNini
CecilieCecilie SiriSiri
10" Water Injection
6/10" Water Injection
4" Gas lift
4" Gas lift12" Multiphase
8" Multiphase
Stine S1
Umbilical
Nini EastNini East
The Siri Complex
Nini
Cecilie Siri
10" Water Injection
6/10" Water Injection
4" Gas lift
4" Gas lift12" Multiphase
8" Multiphase
Stine S1
Umbilical
Nini East
NiniNini
CecilieCecilie SiriSiri
10" Water Injection
6/10" Water Injection
4" Gas lift
4" Gas lift12" Multiphase
8" Multiphase
Stine S1
Umbilical
Nini EastNini East
The Siri Complex
Nini A Unmanned wellhead platform First oil August 2003 Monotower platform Weight 2900 Tonnes 6 Producers 4 Injectors
Cecilie Unmanned wellhead platform First oil August 2003 Monotower platform Weight 2900 Tonnes 3 Producers 1 Injector
The Siri Complex
Nini
Cecilie Siri
10" Water Injection
6/10" Water Injection
4" Gas lift
4" Gas lift12" Multiphase
8" Multiphase
Stine S1
Umbilical
Nini East
NiniNini
CecilieCecilie SiriSiri
10" Water Injection
6/10" Water Injection
4" Gas lift
4" Gas lift12" Multiphase
8" Multiphase
Stine S1
Umbilical
Nini EastNini East
The Siri Complex
Nini
Cecilie Siri
10" Water Injection
6/10" Water Injection
4" Gas lift
4" Gas lift12" Multiphase
8" Multiphase
Stine S1
Umbilical
Nini East
NiniNini
CecilieCecilie SiriSiri
10" Water Injection
6/10" Water Injection
4" Gas lift
4" Gas lift12" Multiphase
8" Multiphase
Stine S1
Umbilical
Nini EastNini East
The Siri Complex
Nini East Unmanned wellhead platform First oil February 2010 Monotower platform Weight 2900 Tonnes 2 Producers 1 Injector Drilling ongoing
Design Basis
Expected Challenges CO2 Corrosion
Scaling
CO2 Corrosion
High CO2 content in Nini East reservoir – 0.76 mol%
Will spread to all producing platforms via liftgas
Existing platforms designed for low CO2 content
A new corrosion strategy was needed
CO2 Corrosion
Selection of an appropriate corrosion inhibitor was based on laboratory testing, which clarified:
Inhibitor performance - including persistency on pipe wall and pitting corrosion; Tendency to form precipitation of gunk or solid matter; Thermal aging and corrosion tendency of neat inhibitor; Compatibility with scale inhibitor under topside and down-hole conditions; Protection of welds with nickel content.
CO2 Corrosion
Followed up by offshore test on Stine
CO2 Corrosion
The corrosion monitoring program was expanded further to include: Online ER-probes (Electrical Resistance) on satellite platforms, logging actual corrosion
rate every 6th hour. The addition of an ECN-probe (Electrical Chemical Noise) is being considered;
In-line corrosion coupons with welds; Ultrasonic and radiographic WTM (Wall Thickness Measurements); Collecting pigging debris for analysis; CMU (Corrosion Monitoring Unit) coupled to side-streams, where coupons are evaluated. Analysis of water composition and residual corrosion inhibitor.
Design Basis
Nini
Cecilie Siri
10" Water Injection
6/10" Water Injection
4" Gas lift
4" Gas lift12" Multiphase
8" Multiphase
Stine S1
Umbilical
Nini East
NiniNini
CecilieCecilie SiriSiri
10" Water Injection
6/10" Water Injection
4" Gas lift
4" Gas lift12" Multiphase
8" Multiphase
Stine S1
Umbilical
Nini EastNini East
Material SelectionInhibitor Injection via Lift Gas
Pigging Debris Analysis
Design Basis
Nini
Cecilie Siri
10" Water Injection
6/10" Water Injection
4" Gas lift
4" Gas lift12" Multiphase
8" Multiphase
Stine S1
Umbilical
Nini East
NiniNini
CecilieCecilie SiriSiri
10" Water Injection
6/10" Water Injection
4" Gas lift
4" Gas lift12" Multiphase
8" Multiphase
Stine S1
Umbilical
Nini EastNini East
ER probes and coupons
Design Basis
Nini
Cecilie Siri
10" Water Injection
6/10" Water Injection
4" Gas lift
4" Gas lift12" Multiphase
8" Multiphase
Stine S1
Umbilical
Nini East
NiniNini
CecilieCecilie SiriSiri
10" Water Injection
6/10" Water Injection
4" Gas lift
4" Gas lift12" Multiphase
8" Multiphase
Stine S1
Umbilical
Nini EastNini East
Sidestream Corrosion Rigs
Design Basis
Nini
Cecilie Siri
10" Water Injection
6/10" Water Injection
4" Gas lift
4" Gas lift12" Multiphase
8" Multiphase
Stine S1
Umbilical
Nini East
NiniNini
CecilieCecilie SiriSiri
10" Water Injection
6/10" Water Injection
4" Gas lift
4" Gas lift12" Multiphase
8" Multiphase
Stine S1
Umbilical
Nini EastNini East
Routine sampling
Design Basis
Nini
Cecilie Siri
10" Water Injection
6/10" Water Injection
4" Gas lift
4" Gas lift12" Multiphase
8" Multiphase
Stine S1
Umbilical
Nini East
NiniNini
CecilieCecilie SiriSiri
10" Water Injection
6/10" Water Injection
4" Gas lift
4" Gas lift12" Multiphase
8" Multiphase
Stine S1
Umbilical
Nini EastNini East
Risk Based Inspection
Scaling
The alternation in composition would result in scaling
0
2
4
6
8
10
0 50 100 150 200 250
Satu
ratio
n Ra
tio
Pressure (Bar)
Siri SCA 2
CaCO3
BaSO4
Reservoir
Bottom Hole
Wellhead
Separator
Degasser
Scaling
An injection system of scale inhibitor via lift gas has been installed, in order to mitigate scaling.
Selection of appropriate scale inhibitor included following tests: Tendency to precipitate or gunk; Scale inhibition efficiency; Compatibility with other chemicals.
Real-life
Real-life and unexpected challenges Deviations in flow rates and temperatures; Compressor performance; Wax precipitation; Severe slugging.
Actual Flowrates
The actual flowrates was lower than expected
0
500
1000
1500
2000
2500
19.02 10.04 30.05 19.07 07.09 27.10
Oil
Sm^3
/day
Nini East Predicted Vs. Actual
Actual Oil Flowrate Predicted Oil Flowrate
0
200
400
600
800
1000
1200
1400
1600
19.02 10.04 30.05 19.07 07.09 27.10
Oil
Sm^3
/day
Nini A Predicted Vs. Actual
Actual Oil Flowrate Predicted Oil Flowrate
Snowball effectLower production More problems
Actual Flowrates
0
50
100
150
200
250
300
350
400
450
19.02 10.04 30.05 19.07 07.09 27.10
Gas k
Sm^3
/day
Nini East Predicted Vs. Actual
Actual Gas Flowrate Predicted Gas flowrate
0
50
100
150
200
19.02 10.04 30.05 19.07 07.09 27.10
Gas k
Sm^3
/day
Nini A Predicted Vs. Actual
Actual Gas Flowrate Predicted Gas Flowrate
Actual Flowrates
0
50
100
150
200
250
300
350
400
19.02 10.04 30.05 19.07 07.09 27.10
GOR
Sm^3
/Sm
^3
Nini East Predicted Vs. Actual
Actual GOR Predicted GOR
0
50
100
150
200
19.02 10.04 30.05 19.07 07.09 27.10
Gas k
Sm^3
/day
Nini A Predicted Vs. Actual
Actual Gas Flowrate Predicted Gas Flowrate
Actual Flowrates
0
20
40
60
80
100
19.02 10.04 30.05 19.07 07.09 27.10
Lift
Gas
kSm
^3/d
ay
Nini East Predicted Vs. Actual
Actual Lift Gas Flowrate Predicted Lift Gas flowrate
0
500
1000
1500
2000
2500
3000
3500
4000
19.02 10.04 30.05 19.07 07.09 27.10Prod
uced
Wat
er S
m^3
/day
Nini A Predicted Vs. Actual
Actual Water Flowrate Predicted Water Flowrate
Temperature
0
5
10
15
20
25
30
35
40
45
50
Tem
pera
ture
[C]
Temperature - Predicted Vs. measured
Expected Temperature [24-04-10] Measured Temperature [24-04-10]
Expected Temperature [29-11-10] Measured Temperature [29-11-10]
Nini East NiniArrival NiniDeparture Siri
Compressor performance
Compressor performance
Compressor capacity was lower than expected Moleweight was out of Spec.
Compressor performance
4 Months after Nini East production started, the compressor was revamped with similar internals
The replaced internals was covered in rust
Compressor performance
Compressor performance
Compressor performance
Compressor performance
~4 kg of deposits was found in the compressor 65% iron oxide 5% iron sulphide 30% organic matter No chlorides or carbonates (indicating no liquid carry from the separators).
Compressor performance
The new internals increased capacity, but it was dropping steadily
Compressor performance
Corrosion happened in wet gas system - downstream LP Acid cleaning was carried out during the investigations Iron-rich water and condensate from knock-out drum was routed back to LP inlet scrubber TEG carry over from Glycol contactor to inlet scrubber for HP-section Mixture of condensate, iron-rich water and TEG entering LP inlet scrubber, provokes foam
formation -> liquid carry-over to LP-compressor
Compressor performance
Cleaning and chemical injection gave good results
Compressor performance
In January the compressor was revamped with new internals, designed for the new mole weight.
Compressor train does now deliver as expected
Wax issue
During routine pigging in NiniA-Siri pipeline a 14m^3 wax plug was formed. It was 160 meters long.
Wax issue
Wax issue
Wax issue
Heavy wax deposits was caused by: Initial WAT ~30C Actual WAT ~34C Lower Nini East temperature Shut-in of high WC wells on Nini A
Wax issue
The main points in the new wax strategy are: Special bypass pigs purchased; High water cut wells at Nini A restarted prior to pigging; Tailor-made chemicals for wax inhibiting/dispersion/dissolving; Mechanical removal of wax in production wells; Downhole injection of chemicals through chemical injection line at Nini East.
A clean-up campaign was performed Semi-intelligent pigging 17 pigs were launched – Increasing effective diameter
Wax issue – Differential pressure
172 mm
172 mm
176 mm
Pipe ID -182 mm
Wax issue
New strategy is successful
No shutdowns
Example (7 Feb 2011) Pressure drop before pigging – 11.6 Bar Pressure drop after pigging – 6.7 Bar Pipeline capacity can be increased by ~ 30%
Slugging
Severe Slugging is a challenge at Siri
The introduction of Nini East resulted in increased flaring
Slugging
Slugging
Challenged by several slug types Terrain-induced slugging Riser-induced slugging Hydrodynamic slugging
AB
C
D
Slugging
Slugging solutions: Manual choking; Automatic choking; Slug catcher; Antifoam injection; Slug handling by slug control valve; Slug mitigation by slug control valve.
Riser induced slugging
ISC System (Cranfield)
Chemical Injection
Slug mitigation (ISC system)
Conclusion
Design basis is not the real world!
Operation procedures has to be reviewed and updated
Be ready for some urgent challenges
Tieback solutions needs the right people at the right time
In spite off challenges: Stable production Prolonged Siri lifetime A valuable asset to the Siri Complex
58
Thank you for your attention!