UNCERTAINTIES IN HYDROCARBON CHARGE PREDICTION

Computer simulations allow the prediction of hydrocarbon volumes, comp osition and charge timing in undrilled petroleum prospects. Whereas di fferent models may give different hydrocarbon charge predictions, it h as now become evident that a dominant cause of erroneous predictions i s the poor quality of input data. The main culprit for prediction erro rs is the uncertainty in the initial hydrogen index (H/C) of the sourc e rock. A 10% uncertainty in the H/C may lead to 50% error in the pred icted hydrocarbon volumes, and associated gas-oil ratio. Similarly, un certainties in the maximum burial temperature and the kinetics of hydr ocarbon generation may lead to 20-50% error. Despite this, charge mode lling can have great value for the ranking of prospects in the same ar ea with comparable geological histories.