- Problem Definition
Offshore Regasification Project has been one of the most priority project. Therefore, calculation of O&M Cost of Offshore Regasification Project must be developed.
The objective of this calculation is to determine cost overrun probability during O&M period. Therefore, it is necessary to prepare cost contingency for the project to anticipate the additional cost.
- Identify the Possible Alternative
There are 4 methods to estimate cost (also time) contingency, as follow:
- Expert Judgment
- Predetermined Guidelines
- Simulation Analysis
- Range Estimation
- Expected Value
- Parametric Modeling
For this case, Author uses Simulation Analysis with Range Estimation method.
Range estimating is a risk analysis technology that combines Monte Carlo sampling, a focus on the few critical items, and heuristics (rules of thumb) to rank critical risks and opportunities. This approach is used to establish the range of the total project estimate and to define how contingency should be allocated among the critical items.
- Development of The Outcome for Alternative
The following steps will be used to determine cost contingency using range estimating:
- Determines of ranges for each cost items.
- Determines the probability that each item can be completed within the estimate.
- Running Monte Carlo simulation for the cost range.
- Determines of critical items based on result of Monte Carlo simulation.
- Determine of contingency with reference to critical items only.
Following are base estimates for each cost items:
Table 1. Base Estimate of O&M Cost Offshore Regasification Facilities
Estimator has developed table (1) above, to determine range of each cost item. Good estimate shall be calculated equal probability of overrun and underrun (50% probability), hence the assumption being that some project will overrun while others will underrun, and in the end they will balance out.
But estimator shall be added some risk-aversed attitude, in this calculation P80 will be used. It means that probability of 80% that the project will not overrun.
Table 2. Range and Desire Probability of Each Component
After determining range and desire probability of component cost, further step is to conduct Monte Carlo simulation with 1000 iterations. The result as follow:
Table 3. Monte Carlo Simulation Result
- Selection Criteria
Estimator using Bottom Line Critical Variance to categorize critical item of each cost component, table show below:
Table 4. Bottom Line Critical Variances
- Analysis & Comparison of Alternative
Using Bottom Line Critical Variance table above, critical item result as follows:
Table 5. Critical Items
- Selection of the Preferred Alternative
After categorize critical component, then the next step is determining cost contingency, as shown in following table:
Table 6. Cost Contingency
Hence the total cost contingency will be used for this project is $ 126.000 (only for critical item).
- Performance Monitoring and The Post Evaluation of Result
During the implementation of Offshore Regasification Project, it is necessary to monitor O&M cost to prevent cost overrun exceed cost contingency.
- AACE International Recommended Practice No. 41R-08
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- AACE International Recommended Practice No. 44R-08
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- Milza, R. (2016). W10_RM_Contingency Estimation in Gas Station Project.
- Asro. Y. W. (2014). W20_YAW_Contingency Estimation in Storage Tank Project.