EXPLICATING A GUT FEEL-BENCHMARKING THE CHANCE FOR EXPLORATION SUCCESS

Abstract

"In labouring to be brief I become obscure"—Horace. There is a 50-50 chance for adequate trap, seal, source, reservoir, and the likelihood for oil. So, the probability for a successful oil-find is three per cent. Brief and to the point? Yes. Comparable to other estimates? Frequently, not. Obscure? Yes.

A check-list of 33 enquiries is offered as a yardstick for measuring the adequacy of petroleum prospect factor conditions. Each of the enquiries is a part of an overall test that good prospects should pass. Application of the check-list results in probability assignments to the chance for commercial exploration success. The length of the check-list for factor assessment may, at first, appear daunting for what experienced explorationists commonly regard as a simple and quick risk assessment task. However, a thorough approach introduces an essential element of uniformity between prospect evaluations. The proposed approach goes to some length to explicate consequential judgements that otherwise may remain unrecorded.

Examples of the application of this method are provided for three prospects in distinctive Australian basin settings. Two of these prospects have been drilled, Nebo ?1 (oil discovery in the offshore Beagle Sub-basin) and Roswin North ?1 (gas discovery in the Bowen Basin). The third feature, the Galapagos prospect in the offshore southern Browse Basin, remains to be drilled.

Subjective ratings of factor adequacy based on analogy are an essential exploration planning tool. Numerical expressions of the chance for successful exploration are routinely, and subjectively based on analogy to successful play-types. Successful models are the yardsticks used to measure the favourability of juxtaposed conditions that combine to define the likelihood that petroleum has been generated, migrated and trapped in reservoirs, and can be exploited at a profit. Subjective ratings (of exploration-factors) often remain implicit and obscure. Inconsistency between prospect assessments can result.

Standards can be set not only to ensure that subjective assessments of exploration prospects are to a large degree comparable, but also to explicitly demonstrate that no relevant criteria have been the subject of neglect in the prospect assessment process. Indeed, expansion into new ventures with finite exploration budgets is incentive to formalise the prospect risk assessment process, no matter how reputable and well experienced are the available expert opinions.

These guide-lines are offered as a basis to:

reduce subjectivity in judging the relative certainty of play-type ingredients;boost internal consistency between exploration prospect assessments;provide an explicit basis for exploration assessment training; andGain management's confidence. Risk assessment is rigorous and 'seen-to-be-done'.

The check-list will also be valuable in farm-in and farm-out discussions. Buyers and sellers are offered some common-ground to mould perceptions.