RISK ANALYSIS APPLIED TO THE APPRAISAL PHASE OF PETROLEUM FIELD

Decision analysis applied to petroleum field development plans are always strongly related to risk due to the uncertainties present in the process. Methodologies to quantify the impact of uncertainties are still not well established due to the amount of variables that must be considered. This situation requires a detailed study using numerical simulation. To make this process possible, some methodologies were developed to use simplification in the Risk Analysis. The objective o f this work is quantify the impact of these simplifications, mainly, by the selection of the ideal number attributes. The simplification procedure treatment applied in this process is based on: (1) definition of the uncertainty attributes number, (2) attributes treatment, (3) sensibility study, (4) gradual combination influence analysis of the less critical attributes in sensibility study, (5) influence of level number of critical attributes, (6) associated probability variation for critical attributes. The simulations results in this process are combined to calculate the NPV (Net Present Value). After the statistical treatment of the results, it is possible to define the Risk Curve.