Post-Mortem Analysis of Exploration Results: A Model-Based Approach
Hall, David M.1, Annick Richard1, Eric Denelle1, Pierre Delfiner2 (1) Total S.A, Paris, France (2) Total E&P, Paris La Defense Cedex, France
Since the creation of the new Group in 2000, Total has carried out post-mortem analyses of over 300 exploration objectives from a the world-wide drilling programme of more than 200 wells located in a variety of geological basins.
Using the in-house post-mortem method, the outcome of each exploration objective is compared with the key elements of the predicted geological model namely; source rock; tim-ing/migration, reservoir, seal, trap geometry, fluid type and in-place hydrocarbon volumes.
The overall outcome is then assessed as being either compliant (agreeing with the predicted model) or non-compliant (disagreeing with the predicted model).
The compliance rate (compliant / non-compliant ratio) provides a convenient way of evaluating the success rate of geological predictions, independent of economically-influ-enced considerations such as recovery factor and non-economic cut-off volumes. The compliance rate differs from the discovery rate (presence of movable hydrocarbons) which, by definition, is always higher.
Post-mortem analysis is an essential part of the exploration cycle. Firstly, lessons learnt help reduce the bias of pre-drill estimates and also help recognise the limits of predictive ability. Secondly, this knowledge is shared on a company-wide basis thus improving the coherency of prospect evaluations between different project teams. As a consequence, centralised portfolio management is also improved.