Oil & Gas UK Decommissioning Insight 2014

Appendix b) Association for the Advancement of Cost Engineering Classifications

1

Primary Characteristic

Secondary Characteristic

2

Level of Project Definition (expressed as % of complete definition)

Expected Accuracy Range Typical Variation in Low and High Range

End Usage Typical Purpose of Estimate

Methodology Typical Estimating Method Capacity factored, parametric models, judgement or analogy Equipment factored or parametric models Semi-detailed unit costs with assembly level line items Detailed unit costs with forced detailed take off Detailed unit cost with detailed take off

Estimate Class

3

L: -20% to -50% H: +30% to +100%

Class 5

0% to 2%

Concept screening

4

L: -15% to -30% H: +20% to +50%

Class 4

1% to 15%

Study or feasibility

5

Budget authorisation or control

L: -10% to -20% H: +10% to +30%

Class 3

10% to 40%

6

Control or bid/ tender

L: -5% to -15% H: +5% to +20%

Class 2

30% to 70%

Check estimate or bid/tender

L: -3% to -10% H: +3% to +15%

Class 1

50% to 100%

7

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