1. Wytch Farm Field Development Project
Photo courtesy of Howard Johnson
Wytch Farm Field Development Project
Friday 2nd of March 2012
This photo is from East Sidmouth and shows the gradational contact between the Mercia Mudstone and the Sherwood Sandstone.
TEAM B
Mohammed Alshawaf , Lanray Hammed Bakare,
Francsico J. Barroso Viseras, Aristeidis Karamessinis,
Ha Nguyen and Shi Su

2. Introduction Cultural information
Location Dorset, Wessex Basin (50°69’,-1°98’)
44 km2, onshore and offshore
Environment outstanding beauty, tourism,
wild life
Cultural information
Location Dorset, Wessex Basin (50°69’,-1°98’)
44 km2, onshore and offshore
Environment outstanding beauty, tourism,
wild life
Underhill & Stoneley, 1988
Source
Seal
Reservoir
Geological overview
Reservoir Sherwood Sandstone
Seal Mercia Mudstone
Source Lias Formation
Play type Tilted fault blocks
Geological overview
Reservoir Sherwood Sandstone.
Seal Mercia Mudstone
Source Lias Formation
Play type Tilted fault blocks
11.8km
Wytch Farm Field
Google Earth, 2011
Mention the age of the formation (Triassic)
Mention the recovery factor
Field appraisal
Producers X-02, 1D-02
Appraisal wells
3D seismic survey
Depth
1585 m
Pressure
2400 psig
Oil column thickness
39 m
Areal extend
40 km2
API gravity
15°C
GOR
320 scf/stb
P90
P50
P10
STOIIP (MMbbl)
580
795
1040
Reserves (MMbbl)
215
290
385

3. Wytch Farm - Development phase - Team B
Aims and Objectives
Develop the geological model
Investigate viable development options
Assess associated static and dynamic uncertainties
Propose a development and production plan
Justify additional data acquisition requirements
Wytch Farm - Development phase - Team B

4. Drive mechanism determination
Develop model
Limitations of material balance
Oil expansion and aquifer drive are the most plausible
No assumption can be validated
Investigate options
N=645 MMBbl
N=300 MMBbl
Propose plan
Use the material balance to present the drive mechanism but keep in mind that with two points any drive mechanism assumption is right. We do not have enough pressure data available. No pressure equilibrium is observed
Present a (nice) graph with the data
No decision can be made based upon MB.
Assess uncertainties
Justify data acquisition
Wytch Farm - Development phase - Team B

5. Recovery mechanism Primary recovery => secondary recovery methods
Develop model
Primary recovery
Low primary recovery: 4.6%
=> secondary recovery methods
Secondary recovery
Water injection preferred
Gas injection not advised: under-saturated oil and low GOR
Possibility of using artificial lift
Investigate options
Propose plan
Why do we use water injection: we have an aquifer (uncertain extent and nature), water available on surface
Why do we use artificial lift: maintain bottom hole pressure just above the bubble point
Why do not we use gas injection: low GOR (so where would the gas come from), under-saturated oil (most of the gas injected would be dissolved in the oil), modest dip…
Assess uncertainties
Justify data acquisition
Wytch Farm - Development phase - Team B

6. Building the simulation model
Main assumptions
Input Fine model (2.5M cells)
Upscaled properties Φ, facies, Kh and Kv
Fluid model Dead oil, relative permeabilities
Capillary pressure neglected for simplification purposes
Output coarse model (82,000 cells, 8 faults)
Develop model
Investigate options
Propose plan
Explain the method used for permeability upscaling
Assess uncertainties
Justify data acquisition
Fine hor. permeability model - Sector
Coarse hor. permeability model - Sector
Coarse horizontal permeability model within Flooding event 1
Fine horizontal permeability model within Flooding event 1

7. Upscaled model consistency
Develop model
Static properties
Geology
Volumetrics
Upscaled properties
kh, kv Φ
Facies
Dynamic properties
Cumulative production
Bottom-hole pressure
Oil saturations
Sweep efficiency
Water cut
Coning water
Numerical diffusion
Investigate options
Propose plan
QC of upscaled volumetric properties (make a table, a bar graph maybe?)
QC of the sector (think about main conclusions)
History match
Assess uncertainties
Justify data acquisition
Wytch Farm - Development phase - Team B

8. Coarse model consistency (history match)
Develop model
Oil rates: good match
Water rates: calibrate the model
Limits: well history, no flow control
Investigate options
Propose plan
Assess uncertainties
Justify data acquisition
Wytch Farm - Development phase - Team B

9. Development strategy Solution 25 producers / 10 injectors 2 wells/m
Develop model
Parameter
Constraint
Solution
Drilling strategy
Number of wells
Recovery factor vs economics
25 producers / 10 injectors
Schedule
Rates and rigs
2 wells/m
Well location
Geology and oil distribution
Uniform
Production strategy
Plateau
Maximise recovery & 5% recovery
3-year plateau
Water injection
Pressure maintenance
After 15 m
Production time
Lease
25 years
Investigate options
Propose plan
Number of wells
Compromise between recovery factor target and economics
Every single well has to increase the production by at least 1 MMBbl
Well placement
A uniform well distribution allows to maintain the pressure better. After trial no pattern was followed
Location optimise based on: geology , pressure drop and oil distribution
Production five meters above the OWC
Injection just below the OWC
Production strategy
3-year-plateau in order to maximise the recovery and get 5% STOIIP per year
Surface facility limitations
Water injection after 15 months
Selected layer completion to reduce water production, no artificial lift
Drilling schedule
Well sequence based upon rates and rig position
Recovery factor
Results
Assess uncertainties
Justify data acquisition
Wytch Farm - Development phase - Team B

10. Development strategy results
Develop model
3-year plateau
Injection starts after 15 months
345 MMBbl recoverable
43% recovery factor based on P50
Investigate options
STOIIP 795 MMBbl
Recovered 345 MMBbl
Propose plan
STOIIP (MMBbl)
Recovered (MMBbl)
Recovery factor
P90
580
239
41%
P50
795
345
43%
P10
1 040
452
Assess uncertainties
Justify data acquisition

11. Sweep efficiency analysis
Develop model
Injection after 15 months
89% sweep efficiency achievable over 25 years
Investigate options
Propose plan
Assess uncertainties
Water breakthrough
Start of water injection
Justify data acquisition

12. Uncertainty analysis
Develop model
Approach combines both static and dynamic parameters
Parameters considered
GRV
Porosity Sw
kH, kV
Corey parameters
Sor, Swc, Swcr
Transmissibilities
Investigate options
Static properties
Dynamic properties
Propose plan
Assess uncertainties
Justify data acquisition
Wytch Farm - Development phase - Team B

13. Reducing uncertainties
Data acquisition plan
Reprocess seismic data
Coring of the first few wells SCAL
Logging
Fluid analysis
Develop model
Investigate options
Propose plan
Core the First 3-5 Wells
Utilize NMR Logging Tool
Independent Source for Permeability and Porosity
Detailed Special Core Analysis
Reduce Relative Permeability and Capillary Pressure Uncertainty
RFT All Wells
Evaluate Reservoir Connectivity, Faults transmissibility, Aquifer Strength
Aid in History Match
Adequate Fluid Sampling for Detailed PVT Analysis
SBHP/T Measurements Twice Yearly
Rate Test Wells on a Monthly Bases
Run PLTs Every 3-4 Years
Separator and Wellhead Samples
Solid production
Composition
Temperature surveys
Wellhead Integrity Tests
Annuli Surveys
Assess uncertainties
Justify data acquisition

14. Wytch Farm - Development phase - Team B
Conclusions
High recovery factor
High sweep efficiency
Only water injection used
Good understanding of uncertainties
Number of wells
25 producers / 10 injectors
Drilling schedule
2 wells/m
Well location
Uniform
Plateau
3-year plateau
Water injection
After 15 m
Production time
25 years
Recovered (MMBbl)
Recovery factor
P90
239
41%
P50
345
43%
P10
452
Wytch Farm - Development phase - Team B

15. Wytch Farm - Development phase - Team B
Thank you
Any questions ?
Wytch Farm - Development phase - Team B

16. Geology and upscaled properties: facies
Develop model
Fine grid
Coarse grid
Investigate options
Propose plan
Assess uncertainties
Justify data acquisition
Wytch Farm - Development phase - Team B

17. Volumetrics QC 2.8% 1.4% 0.8% Wytch Farm - Development phase - Team B
Develop model
Investigate options
Propose plan
2.8%
1.4%
0.8%
Assess uncertainties
Justify data acquisition
Wytch Farm - Development phase - Team B

18. Upscaled properties: kh
Fine grid
Coarse grid
Develop model
Investigate options
Propose plan
Assess uncertainties
Justify data acquisition
Wytch Farm - Development phase - Team B

19. Upscaled properties: Φ
Develop model
Porosity distribution: Fine vs Coarse grid
Investigate options
Propose plan %
Assess uncertainties
Justify data acquisition
Wytch Farm - Development phase - Team B

20. Cumulative production
Develop model
Investigate options
- Fine grid
Propose plan
- Coarse grid
Assess uncertainties
Justify data acquisition
Wytch Farm - Development phase - Team B

21. Bottom-hole pressure - Coarse grid - Fine grid Injectors Producers
Develop model
- Coarse grid
Investigate options
- Fine grid
Propose plan
Assess uncertainties
Injectors
Producers
Justify data acquisition
Wytch Farm - Development phase - Team B

22. Oil saturations Fine grid Coarse grid
Develop model
Investigate options
Propose plan
Assess uncertainties
Justify data acquisition
Wytch Farm - Development phase - Team B

23. Sweep efficiency Wytch Farm - Development phase - Team B Develop model
Investigate options
Propose plan
Assess uncertainties
Justify data acquisition
Wytch Farm - Development phase - Team B

24. Water cut - Fine grid - Coarse grid
Develop model
Investigate options
- Fine grid
Propose plan
- Coarse grid
Assess uncertainties
Justify data acquisition
Wytch Farm - Development phase - Team B

25. Coning water Fine grid Coarse grid
Develop model
Investigate options
Propose plan
Assess uncertainties
Justify data acquisition
Wytch Farm - Development phase - Team B

26. Numerical diffusion Coarse grid Fine grid
Develop model
Investigate options
Propose plan
Assess uncertainties
Justify data acquisition
Wytch Farm - Development phase - Team B

27. History match per well Wytch Farm - Development phase - Team B
Develop model
Investigate options
Propose plan
Assess uncertainties
Justify data acquisition
Wytch Farm - Development phase - Team B

28. Justify data acquisition
Drilling schedule
Priority based on rate and rig location (two rigs: E, W)
Develop model
Investigate options
Propose plan
Assess uncertainties
Justify data acquisition

29. Well location
Well positioning based on the geology and the properties (kh)
Develop model
Investigate options
Propose plan
Assess uncertainties
Justify data acquisition
Wytch Farm - Development phase - Team B

30. Water injection strategy
Water injection after 15 months in order to ensure pressure maintenance
Develop model
Investigate options
Propose plan
Assess uncertainties
Justify data acquisition
Wytch Farm - Development phase - Team B

31. Buckley-Leverett analysis
Develop model
Investigate options
Propose plan
Assess uncertainties
Justify data acquisition
Wytch Farm - Development phase - Team B

32. Relative permeability analysis
Develop model
Investigate options
Propose plan
Assess uncertainties
Justify data acquisition
Wytch Farm - Development phase - Team B