Abstract
JNOC (Japan National Oil Corporation) has been evaluating "geologic chance of success (i. e. probability of finding oil or gas)" and "probabilistic reserves distribution" for exploration prospects since 1997 and has been carrying out post audit to compare the results with predictions to improve qualities of the evaluation since 1999.
This paper introduces the overview of results of the JNOC's geologic risk evaluation over more than five years. Post audit has been recognized as an important process to monitor and improve evaluation accuracy in the prediction of geologic risk. Four main factors/indicators have been compared between predictions and results in JNOC's post audit: (i) predicted versus actual success ratios, (ii) predicted critical risk versus actual failure reason for dry holes, (iii) expected reserves for each prospect versus size of discovery, and (iv) expected reserves for the portfolio versus actual amount of discoveries.
