Swanson's 30-40-30 rule

摘要

Evaluation of the possible range of reserves associated with a pros- pect is a key part of risk taking in hydrocarbon exploration. The challenge of presenting a range of geologically possible models for a range of prospect reserve estimates is addressed using Swanson's 30-40-30 rule. Swanson's rule defines the mean as 0.3PlO + 0.4Pso + 0.3Pgo1 and provides a good approximation to the meanvalues for modestly skewed distributions. Pragmatic and mathematical jus- tifications for this rule are given. Applications of the rule to a his- torical field size distribution and a specific prospect evaluation dem- onstrate its efficacy in handling routine problems in hydrocarbon exploration, with particular reference to use with the lognormal distribution .