CAPEX Estimation
Bottom-up build by scope element — engineering, preparation, well P&A, removal, transport, onshore disposal and site verification — to a stated AACE estimate class.
// Service 05
Techno-Economic Studies
Cost estimates built from vessel spreads, weather downtime and real productivity — not from a percentage applied to last project's number.
Overview
Decommissioning cost estimates fail in a predictable way. The engineering quantities are reasonable, but the productivity assumptions, weather downtime and vessel mobilisation logic are optimistic — and the estimate is presented as a single number with a contingency percentage that hides which assumptions actually drive it.
VORYX builds estimates bottom-up from the execution plan: spread composition, day rates, transit and mobilisation, cycle times per lift or per cut, and weather downtime modelled against real metocean data for the campaign season.
The output is a cost model the client can interrogate — change the vessel class, the campaign window or the disposal route and see what happens, rather than commissioning a new study.
Scope of Work
OPEX & Cost of Delay
Running cost of keeping an asset lit and manned, integrity spend, and the economics of deferral versus early execution.
Benchmarking
Comparison against regional and international unit rates — cost per well, per tonne removed, per kilometre of pipeline — with normalisation for water depth, weight and location.
Economic Modelling
Discounted cashflow, provisioning and liability profiles, tax and relief treatment where applicable, and funding-schedule alignment.
Sensitivity & Probabilistic Analysis
Monte Carlo simulation on the drivers that matter — weather, vessel rate, scope growth, well complexity — producing P10 / P50 / P90 rather than one number.
Value Engineering
Structured challenge of scope, method and sequence to remove cost without moving risk — campaign bundling, spread rationalisation, reuse and recycling value recovery.
Methodology
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1
Fix the estimate basis
State the estimate class, the scope boundary, the pricing date, the currency and escalation, and every exclusion — before any number is produced.
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2
Quantify from engineering
Take quantities from the engineering deliverables — tonnages, lift counts, cut counts, pipeline lengths, well categories — not from analogue scaling.
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3
Build the execution model
Spread composition and day rates, cycle times, transit, mob / demob, and weather downtime from metocean statistics for the actual campaign season and location.
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4
Benchmark and challenge
Test unit outcomes against market data and recent comparable campaigns. Where our number differs materially from the benchmark, we explain why rather than adjusting to match.
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5
Risk and contingency
Quantified risk register feeding a probabilistic model, so contingency is derived from identified risks rather than applied as a flat uplift.
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6
Hand over a live model
Deliver the cost model itself, documented and auditable, so the client can re-run scenarios as the project definition matures.
Deliverables
- Cost estimate report with stated basis, class and exclusions
- Bottom-up CAPEX model (auditable, client-retained)
- OPEX and cost-of-delay analysis
- Benchmarking report against regional and global unit rates
- Probabilistic cost analysis — P10 / P50 / P90
- Weather downtime model and campaign window analysis
- Quantified risk register with contingency derivation
- Value engineering register with savings and risk impact
- Provisioning and liability profile for financial reporting
- Estimate reconciliation against tender returns
Standards & Codes
Work is delivered against the applicable international and regional framework. The codes below are those most commonly governing this scope — the controlling set is confirmed per project and jurisdiction.
- AACE International RP 18R-97 Cost estimate classification system
- AACE RP 17R-97 Cost estimate classification
- ISO 15686-5 Lifecycle costing
- NSTA cost benchmarking UKCS decommissioning cost and performance data
- IOGP / OEUK benchmarks Industry unit-rate reference data
Frequently Asked
What estimate class can you deliver at study stage?
Class 5 at screening, Class 4 at concept select, and Class 3 once the execution method, vessel class and disposal route are defined. We state the class explicitly and the definition level that supports it.
How do you handle weather downtime?
Modelled from metocean statistics for the specific location and campaign season against the operability limits of the chosen spread — not as a flat percentage. Downtime is usually one of the top three cost drivers and deserves to be treated as one.
Can you benchmark our existing estimate?
Yes. An independent review of an existing estimate — basis, quantities, productivity assumptions, contingency derivation and benchmark position — is one of our most requested short scopes.
Do we get the model or just the report?
Both. The cost model is a deliverable, documented so your team can run scenarios without coming back to us for every question.
Want an estimate you can defend?
Talk to an engineer who has delivered this scope offshore.
Discuss your project