1. Base Case Simulation Model
Base case model is run by eclipse in order to predict field performance
This model is utilized as the main reference for the use of comparing with other simulation
Input Data
Input
Value
Number of wells 32
Type of well
Deviated
Depletion method
Natural depletion
Production control mode
Control by oil rate
Oil Rate
150 SM3/Day
Water Cut Limit for the field
0.5
Gas Oil ratio limit
100 SM3/Day
Run Duration
20 years

2. Base Case Model Result

3. Base Case Simulation Result
Base Case Model
Result
Cumulative Oil Production
32.78 million m3
Recovery Percentage
8.25%
Drive mechanism
Water aquifer and Gas Cap
Pressure depletion
2.00 Bar/ Year
Base Case scenario suggest that :
Oil production shall be controlled by 150 SM3/Day
GOR shall be controlled by 100 SM3/SM3
Water cut shall be controlled by 0.5 SM3/SM3
Secondary recovery shall start after Years of the start of the primary production.

4. Development Strategy
Based on the result obtained from the base case model-Gullfaks reservoir has dominant in water aquifer and gas cap as drive mechanism
Able to support the reservoir pressure at a constant pseudo steady state decline rate
Utilized water injection in order to support reservoir pressure and prevent further expansion of gas cap as the pressure drop below the bubble point
Reservoir with big gas cap and water aquifer will result in 20-40% oil recovery
Improved from primary recovery of 20 years production for 32 wells with only 8.25% oil recovery

5. Sensitivity analysis for Water Injection Strategy
Sensitivity analysis shows to what extent the viability of a project is influenced by variations in major quantifiable
Technique to investigate the impact of changes in project variables on the base case
Purpose of doing sensitivity analysis is to help to identify the key variables which influence the project effectiveness
Reservoir performance can be optimized by doing sensitivity analyses based on the simulation base case result
Sensitivity analyses are also performed to rank the importance of reservoir parameters which affects production performance which are :
Number of injection wells
Injection rate
Injection start time

6. Sensitivity analysis for Water Injection Strategy
1. Number of injection well
Injection Well = C2,C3,C4,C5 and C6
Variable
Case 1
Case 2
Case 3
Case 4
Case 5
Number of Injection well 1 2 3 4 5
Start of injection
After 20 years of Primary Production
Injection Rate
Same as production control mode rate ( 150 SM3 )
Duration of injection Strategy
25 years
Additional Oil Recovery
10.10%
10.23%
10.31%
10.25%
10.18%
Optimum Recovery

7. Sensitivity analysis for Water Injection Strategy
2. Injection rate
Variable
Case 1
Case 2
Case 3
Case 4
Case 5
Number of Injection well
3 injectors
Start of injection
After 20 years of Primary Production
Injection Rate (SM3/ Day )
150
200
250
300
350
Duration of injection strategy
25 Years
Additional Oil Recovery
10.31%
10.41%
10.62%
10.65%
10.63%
Optimum Recovery

8. Sensitivity analysis for Water Injection Strategy
3. Injection start time
Variable
Case 1
Case 2
Case 3
Case 4
Case 5
Number of Injection well
3 injectors
Start of injection after primary production ( Year) 5 10 15 20
Injection Rate ( SM3/ Day )
300
Duration of Injection strategy
25 Years
Additional Oil Recovery
10.49%
10.52%
10.74%
10.68%
10.65%
Optimum Recovery

9. Sensitivity analysis for Water Injection Strategy
Summary of analysis
Variable
Optimum Water injection case
Number of injection Wells
3 injectors
Start of Injection after primary production
10 years
Injection Rate
300 SM3/ Day
Duration of Injection strategy
25 Years
Additional Oil recovery
10.74%

10. Proposed water injection strategy simulation result
Water flooding data input
Input
value
Number of wells 32
Type of wells
Deviated
Strategy method
Water flooding
Injection Rate
300 SM3/Day
Injection Well
C3, C4 and C6
Oil rate
30 SM3/ Day
Water Cut Limit for the field
0.5
Gas oil ratio limit
100 SM3/SM3
Action if limits are violated
Shut worst well

11. Proposed water injection strategy simulation result

12. Proposed water injection strategy simulation result

13. Proposed water injection strategy simulation result
Comparison of simulation result between water injection and base case
Water Injection Strategy
Result
Cumulative Oil Production
56 million m3
Recovery Percentage
10.74%
Drive mechanism
Water injection ( Secondary Recovery)
Pressure depletion
Maintain at Bar/ Year of injection
Base Case Model
Result
Cumulative Oil Production
32.78 million m3
Recovery Percentage
8.25%
Drive mechanism
Water aquifer and Gas Cap
Pressure depletion
2.00 Bar/ Year