PREDICTION OF VOLUMES AND RISK IN HYDROCARBON EXPLORATION - A QUANTIFICATION OF GEOLOGY

The prediction of the hydrocarbon potential of a specific trap or of a number of specific traps (venture), referred to herein as prospect ap praisal, concerns a probabilistic exercise based on the quantification of geology in terms of structural closure, reservoir quality, hydroca rbon charge, and the retention potential of the seal. Its objectives i nclude: (a) prediction of the hydrocarbon volumes that could be presen t in the trap from an analysis of its geologic attributes; (b) the amo unt of uncertainty introduced in the volumetric prediction by the unce rtainties in the subsurface geology; (c) the risk that one or more of the essential attributes of the prospect are underdeveloped and recove rable reserves are absent. The uncertainty of the geologic input requi res a probabilistic approach, for which the Monte Carlo procedure is w ell suited. Prospect appraisal forms the basis for decision-making in oil exploration and development and, therefore, should be reliable, co nsistent, and auditable. This requires the use of a consistent methodo logy, the development of reliable models to quantify the geologic proc esses involved, and the collection of comprehensive and relational dat abases for the many geologic variables. As a result of data availabili ty, uncertainty and risk tend to increase strongly from mature, produc ing basins to areas of frontier exploration. This may complicate manag ement of exploration portfolios.