Uncertainty Analysis in History Matching and Geologic Models - Case Study

This work presents a study done to support the implementation of a water injection project in a mature oil field located in the Potiguar basin, northeast of Brazil. Techniques of uncertainty analysis were used, from the geological modeling to the flow simulation phase to preserve geologic realism and the history matching. This leads to a more reliable forecasting and results in an increased knowledge of reservoir’s uncertainty, considering multiple history-matched models rather than a single best model for forecasting. Multiple geological models were prepared considering the field production history. A streamline simulator was used to achieve this goal. These types of simulators are fast enough to give a quick evaluation about the behavior of the geological models relatively to the flow inside the reservoir. The most representative models were then chosen by looking at the probability of occurrence of the geological parameters and the best fit of the historical production. Models created this way allow a precise and fast adjustment during flow simulation, reducing frequent reanalysis of the geological models to correct distortions in their cell-to-cell connectivity.