A ‘sense check’ method for incorporating seismic amplitude information into prospect risk (a tribute to Mike Bacon)

Abstract

A simple Bayesian formulation is proposed as the basis of a prospect risking method that updates an initial geological chance of success by incorporating seismic DHI (direct hydrocarbon indicator) information. The key parameter is the ratio (R) of the probabilities P(dhi|hc) and P(dhi|nohc) (i.e. the relative probability that the DHI effects are due to the presence of hydrocarbons). The model proposed is that R is directly related to the number of first order DHIs with a subsequent modification by calibration and quality factors. This provides an understandable tool, which enforces a degree of objectivity to the amplitude update process and can be employed by geologists and geophysicists readily in the risking discussion. It is shown that the methodology is consistent with published statistics of drilled amplitude prospects.