paper no.: spe-202360-ms
TRANSCRIPT
SPE-202360-MS • Probabilistic Assessment of Pressure Depletion and Inflation and its Impact on the Drilling Sequence for the Sangomar Field, Senegal • L. Gavin & P. Jagtenberg
Paper No.: SPE-202360-MSPaper Title: Probabilistic Assessment of Pressure Depletion and Inflation and its Impact on the Drilling Sequence for the Sangomar Field, Senegal
Lisa Gavin & Pieter Jagtenberg, Woodside Energy
1
SPE-202360-MS • Probabilistic Assessment of Pressure Depletion and Inflation and its Impact on the Drilling Sequence for the Sangomar Field, Senegal • L. Gavin & P. Jagtenberg
2
S540
S520
S480S460
Gas Oil Water
Location and Field Overview
Field Location
Reservoirs
Schematic Subsea Layout
SANGOMAR DEVELOPMENT, SENEGAL
SPE-202360-MS • Probabilistic Assessment of Pressure Depletion and Inflation and its Impact on the Drilling Sequence for the Sangomar Field, Senegal • L. Gavin & P. Jagtenberg
Drilling Sequence DriversSANGOMAR DEVELOPMENT, SENEGAL
Subsurface uncertainty
Well execution learning
Water injector learnings
Borehole stability
Rig movesProduction attainment
Rig services & equipment
Material procurement
SPE-202360-MS • Probabilistic Assessment of Pressure Depletion and Inflation and its Impact on the Drilling Sequence for the Sangomar Field, Senegal • L. Gavin & P. Jagtenberg
Safe Mud Window Depends on Near Wellbore Reservoir Pressure
Reservoir pressure (psi)
Equi
v. m
ud w
eigh
t (SG
)BHS min. mud weight
SG=1.0
Pri
Intact shale fracturing
Max. ‘safe’ depletion
SPE-202360-MS • Probabilistic Assessment of Pressure Depletion and Inflation and its Impact on the Drilling Sequence for the Sangomar Field, Senegal • L. Gavin & P. Jagtenberg
Safe Mud Window is Well Dependent
σ3
σ2
Well azimuthImpacts horizontal stresses
acting on wellbore
Well length & casing designDrive friction and ECD
WE
Depth seabed vs. reservoir Drives formation stresses
P
Depletion & InflationImpacts pore
pressure and stresses in post-RFSU wells
SPE-202360-MS • Probabilistic Assessment of Pressure Depletion and Inflation and its Impact on the Drilling Sequence for the Sangomar Field, Senegal • L. Gavin & P. Jagtenberg
S520 (m)
C.I. = 25 m
Oil producer
Water injector
Channel
Karst Lineament
S520 Reservoir Models & ClusteringSANGOMAR DEVELOPMENT, SENEGAL
Simulation ScenariosDevelopment
• x6 oil producers
• x6 water injectors
SPE-202360-MS • Probabilistic Assessment of Pressure Depletion and Inflation and its Impact on the Drilling Sequence for the Sangomar Field, Senegal • L. Gavin & P. Jagtenberg
S520 (m)
C.I. = 25 m
Oil producer
Water injector
Channel
Karst Lineament
S520 Reservoir Models & ClusteringSANGOMAR DEVELOPMENT, SENEGAL
Simulation ScenariosDevelopment
• x6 oil producers
• x6 water injectors
• x9 static models – facies & structure
• x2 Gas cap – y /n
• x2 SCAL – base and fast water
SPE-202360-MS • Probabilistic Assessment of Pressure Depletion and Inflation and its Impact on the Drilling Sequence for the Sangomar Field, Senegal • L. Gavin & P. Jagtenberg
S520 (m)
C.I. = 25 m
Oil producer
Water injector
Channel
Karst Lineament
• x9 static models – facies & structure
• x2 Gas cap – y /n
• x2 SCAL – base and fast water
• x2 Karst lineament transmissibility
S520 Reservoir Models & ClusteringSANGOMAR DEVELOPMENT, SENEGAL
Simulation ScenariosDevelopment
• x6 oil producers
• x6 water injectors
SPE-202360-MS • Probabilistic Assessment of Pressure Depletion and Inflation and its Impact on the Drilling Sequence for the Sangomar Field, Senegal • L. Gavin & P. Jagtenberg
S520 (m)
C.I. = 25 m
Oil producer
Water injector
Channel
Karst Lineament
• x9 static models – facies & structure
• x2 Gas cap – y /n
• x2 SCAL – base and fast water
• x2 Karst lineament transmissibility
• x3 Channel transmissibility
S520 Reservoir Models & ClusteringSANGOMAR DEVELOPMENT, SENEGAL
Simulation ScenariosDevelopment
• x6 oil producers
• x6 water injectors
SPE-202360-MS • Probabilistic Assessment of Pressure Depletion and Inflation and its Impact on the Drilling Sequence for the Sangomar Field, Senegal • L. Gavin & P. Jagtenberg
S520 (m)
C.I. = 25 m
Oil producer
Water injector
Channel
Karst Lineament
• x9 static models – facies & structure
• x2 Gas cap – y /n
• x2 SCAL – base and fast water
• x2 Karst lineament transmissibility
• x3 Channel transmissibility
S520 Reservoir Models & ClusteringSANGOMAR DEVELOPMENT, SENEGAL
Simulation Scenarios
= 216 models = 20 modelsK medoid clustering
Development
• x6 oil producers
• x6 water injectors
SPE-202360-MS • Probabilistic Assessment of Pressure Depletion and Inflation and its Impact on the Drilling Sequence for the Sangomar Field, Senegal • L. Gavin & P. Jagtenberg
S520 (m)
C.I. = 25 m
Oil producer
Water injector
Channel
Karst Lineament
Clustering Inputs
= 216 models = 20 modelsK medoid clustering
SANGOMAR DEVELOPMENT, SENEGAL
Cumulative oil, gas & water at 3,
5 & 25 yrs
Present value of oil at 25 yrs
Maximum oil rate
Oil plateau duration
Recovery factor at 25 yrs
Medoids assessed on cumulative distribution for all input variables
S520 Reservoir Models & Clustering
SPE-202360-MS • Probabilistic Assessment of Pressure Depletion and Inflation and its Impact on the Drilling Sequence for the Sangomar Field, Senegal • L. Gavin & P. Jagtenberg
S520 (m)
C.I. = 25 m
Oil producer
Water injector
Channel
Karst Lineament
S520 Reservoir Models & ClusteringSANGOMAR DEVELOPMENT, SENEGAL
= 216 models = 20 modelsK medoid clustering
Clustering Visualisation
SPE-202360-MS • Probabilistic Assessment of Pressure Depletion and Inflation and its Impact on the Drilling Sequence for the Sangomar Field, Senegal • L. Gavin & P. Jagtenberg
Reservoir Simulation ResultsSANGOMAR DEVELOPMENT, SENEGAL
Active Water Producer
Active Oil Injector
Planned Water Injector
Well of Interest
DepletionProduction
InflationInjection
ΔPressure (psi)
125010007505002500-250-500-750-1000-1250
Different modelsSame timestep, well sequence and production ramp up
Model A Model B
2500m
SPE-202360-MS • Probabilistic Assessment of Pressure Depletion and Inflation and its Impact on the Drilling Sequence for the Sangomar Field, Senegal • L. Gavin & P. Jagtenberg
Reservoir Simulation ResultsSANGOMAR DEVELOPMENT, SENEGAL
Active Water Producer
Active Oil Injector
Planned Water Injector
Well of Interest
DepletionProduction
InflationInjection
ΔPressure (psi)
125010007505002500-250-500-750-1000-1250
Different modelsSame timestep, well sequence and production ramp up
Model A Model B
2500m
SPE-202360-MS • Probabilistic Assessment of Pressure Depletion and Inflation and its Impact on the Drilling Sequence for the Sangomar Field, Senegal • L. Gavin & P. Jagtenberg
100300400500600800
0
50
Integrating borehole stability & simulation resultsSANGOMAR DEVELOPMENT, SENEGAL
Depletion (psi)
Simulation Max amount of depletion
Chance of natural fractures reactivating (if present)
Pie chart proportion = probability of that depletion being encountered
Simulation range of outcomes
Natural fractures reactivate (if present)
due to depletion
Borehole stability allowable depletion
SPE-202360-MS • Probabilistic Assessment of Pressure Depletion and Inflation and its Impact on the Drilling Sequence for the Sangomar Field, Senegal • L. Gavin & P. Jagtenberg
100300400500600800
0
50
Integrating borehole stability & simulation resultsSANGOMAR DEVELOPMENT, SENEGAL
Depletion (psi)
The picture can't be displayed.
The picture can't be displayed.
The picture can't be displayed.
Simulation Max amount of depletion
Chance of natural fractures reactivating (if present)
Pie chart proportion = probability of that depletion being encountered
Simulation range of outcomes
Natural fractures reactivate (if present)
due to depletion
Borehole stability allowable depletion
SPE-202360-MS • Probabilistic Assessment of Pressure Depletion and Inflation and its Impact on the Drilling Sequence for the Sangomar Field, Senegal • L. Gavin & P. Jagtenberg
Well Sequence ImpactSANGOMAR DEVELOPMENT, SENEGAL Order Allowable
depletionBHS / MW / depletion
issues
Updated order
Allowable depletion
BHS / MW / depletion residual issues and mitigations
First Oil Window
1 1
2 2
3 3
4 10Accelerate ‘vulnerable’ S500
producer wells, to be completed before RFSU
Spread early production between north and south of the field
5 5
6 19
7 7
8 13
9 11
First Oil
10 18
11 9
12 14 Accelerate northern water injector
13 9
14 Wells exposed to potentially
severe depletion
12 Wells exposed to depletion risk, to be managed by better balanced
offtake and water injection. The two residual ‘vulnerable’ wells may be accelerated if higher mud weights confirmed to be required
15 15
16 17
17 8
18 4
Alternating producer-injector wells to manage depletion risk
19 22
20 20
21 Wells exposed to potentially
severe depletion
21
22 19
23 22
A
A
A. Wells exposed to potentially severe depletion
SPE-202360-MS • Probabilistic Assessment of Pressure Depletion and Inflation and its Impact on the Drilling Sequence for the Sangomar Field, Senegal • L. Gavin & P. Jagtenberg
Well Sequence ImpactSANGOMAR DEVELOPMENT, SENEGAL Order Allowable
depletionBHS / MW / depletion
issues
Updated order
Allowable depletion
BHS / MW / depletion residual issues and mitigations
First Oil Window
1 1
2 2
3 3
4 10Accelerate ‘vulnerable’ S500
producer wells, to be completed before RFSU
Spread early production between north and south of the field
5 5
6 19
7 7
8 13
9 11
First Oil
10 18
11 9
12 14 Accelerate northern water injector
13 9
14 Wells exposed to potentially
severe depletion
12 Wells exposed to depletion risk, to be managed by better balanced
offtake and water injection. The two residual ‘vulnerable’ wells may be accelerated if higher mud weights confirmed to be required
15 15
16 17
17 8
18 4
Alternating producer-injector wells to manage depletion risk
19 22
20 20
21 Wells exposed to potentially
severe depletion
21
22 19
23 22
A
A
A. Wells exposed to potentially severe depletion
B. Spread early production between north and south of field
C. Accelerate northern water injector
D. Alternating producer-injector wells to manage depletion risk
B
C
D
E
S500 Producer
Gas Injector
S400 Water Injector
S500 Water Injector
S400 Producer
Well typeTheoretical allowable depletion
0 psi
up to 50 psi
50-100 psi
>100 psi
SPE-202360-MS • Probabilistic Assessment of Pressure Depletion and Inflation and its Impact on the Drilling Sequence for the Sangomar Field, Senegal • L. Gavin & P. Jagtenberg
ConclusionsSANGOMAR DEVELOPMENT, SENEGAL
• Many factors need to be taken into consideration when designing a well drilling sequence
• Pressure inflation and depletion impacts mud weight windows
• Borehole stability assessment defines mud weight windows
• Probabilistic simulation determines potential pressure changes in reservoir
• Combining borehole stability & simulation results identifies wells at risk
• Well sequence updated to mitigate drillability risk while still protecting production attainment
SPE-202360-MS • Probabilistic Assessment of Pressure Depletion and Inflation and its Impact on the Drilling Sequence for the Sangomar Field, Senegal • L. Gavin & P. Jagtenberg
AcknowledgementsSANGOMAR DEVELOPMENT, SENEGAL
• Woodside Energy & our RSSD Joint Venture (JV) partners Capricorn Senegal Limited (Cairn), La Societe Des Petroles Du Senegal (Petrosen) & Far Senegal RSSD SA (FAR) for permission to share the work
• Jurgen Streit, Samantha Prior & the Woodside Geomechanics team
• Clinton Di Labio & the Woodside Sangomar Drilling and Completions team
• Mohammad Zafari for guidance on reservoir simulation models and workflows
• Madeline Hardy with the Woodside Data Science and Subsurface Technology Teams in collaboration with SCERF (Stanford Centre for Earth Resource Forecasting) for creating the EMVAT tool used for clustering
• Numerous other Woodside colleagues and JV partners who contributed to building the subsurface models, had helpful conversations with us on this topic & reviewed this paper