Accurate cost estimation is one of the biggest challenges in upstream oil and gas project development. From conceptual screening through to final investment decision, teams need reliable capital expenditure forecasts that reflect the maturity of available engineering data. The AACE International Recommended Practice 18R-97 provides a five-class framework that maps estimate accuracy to project definition level, giving stakeholders a common language for communicating cost certainty.
Class 5 estimates, often called order-of-magnitude or screening estimates, are produced when less than two percent of engineering is complete. They carry expected accuracy ranges of minus twenty to minus fifty percent on the low side and plus thirty to plus one hundred percent on the high side. As projects mature through pre-FEED and FEED phases, estimates progress to Class 3 and Class 2 with increasingly narrow accuracy bands. Understanding where your estimate sits on this spectrum is critical for risk-adjusted decision-making and for setting appropriate contingency levels.
Modern software platforms can accelerate this process by combining power-law scaling correlations with regional cost multipliers and equipment-level factored estimates. By automating the methodology while keeping calculations transparent and auditable, engineering teams can produce AACE-aligned estimates in hours rather than weeks, freeing up time for the judgment-intensive work that drives better project outcomes.