An Empirical Approach to Reduce Uncertainty when Predicting Hydrocarbon Column Heights during Prospect Evaluation

Pre-drill volume estimation in exploration involves a number of input parameters that carry a degree of uncertainty. The largest contributor to the pre-drill volume uncertainty is typically the hydrocarbon column height, which is controlled by both charge and seal behaviour. However, it is this parameter that E&P companies often find the hardest to predict, partly due to the lack of sufficient empirical data from existing fields and discoveries. A new empirical dataset has been compiled, which contains hydrocarbon column height, trap height, overburden thickness and trap fill percentage values for over 240 discoveries across the Norwegian Continental Shelf. The data has been aggregated into a probability tree to calculate the likelihood of a discovery containing different ranges of trap fill, depending on its burial depth and trap height. Results show that for a discovery with a given trap height, the probability of recording 100% fill increases when the overburden thickness increases. Equally, when the trap height increases for a given overburden thickness, the probability of discovery 100% trap fill decreases. These findings, amongst others strongly indicate the need to integrate trap height and overburden dimensions to assess suitable hydrocarbon column heights to use when estimating pre-drill volumes.