An interesting article relating to depth conversion, reservoir closure, confidence and volumetrics appears in the EAGE First Break publication, Volume 35, April 2017, written by Nick Crabtree (Premier Oil). You can read the article here.
In the paper, Nick discusses the question of closure confidence relating to the size and scale of a field, whereby he examines and compares the time map of his sample field with a couple of simple depth maps, assessing how it may be possible to determine which is ‘best’ in the context of an oil field depth map. In his study, Nick creates several thousand depth maps, subsequently using cross validation as his technique to determine the best depth map(s). Through this process, field size variation is statistically analysed to determine the size, volume and uncertainty associated with the prospect. The findings of this study suggest that the map which best predicts the most likely depth at each location within the oil field shows no correlation to the map which predicts the most likely volume of oil.
Nick’s work is of relevance to the 2017 version of Velit, as we incorporate a slightly different cross validation technique to assess the robust nature of the velocity model per layer, and utilise the Monte Carlo multiple realisation technique for the process of determining the reservoir closure, depth conversion confidence and volumetric range.
The new ‘Combinations for Cross Validation tool’ in Velit enables you to select a number of different depth conversion functions per layer, with the total possible number of combinations between the wells in your project scaled to a Gaussian distribution, to run in an efficient and timely manner. The software then plots the stability of the various functions that you have selected against each other, in real time, quickly giving you an understanding of the robust nature of a specific function vs another.
If you are interested in finding out more about our new depth conversion and uncertainty features available in Velit 2017, then please contact us to schedule a demonstration on sales@equipoisesoftware.com
