Assessment of the uncertainty associated with three phase flow recovery processes by using simulation models calibrated by two phase recovery processes

Oil reservoirs are very complex systems with flow properties varying from the pore to reservoir scale. To simulate fluid flow in the reservoir, there are many uncertainties ranging from the spatial distribution of basic rock properties to the quantification and impact of rock/fluid SCAL models of hysteresis and wettability. The process of history matching attempts to reasonably reproduce the past field performance by fine tuning some or all of these uncertain parameters while reasonably maintaining their physical nature in the simulation model. It is well known that well history matched simulation models are more trustworthy in predicting future reservoir performance. Errors in these future performance predictions may be introduced, however, when future development plan include processes that were not experienced historically.;In this study, Validity and reliability of simulation models, that has been history matched by two-phase flow processes of water flooding, to predict the performance of three-phase flow of WAG processes was assessed. To do that, fine grid of two 5-spot sectors model was built and then upscaled. Upscaled model was then history matched to the results obtained from the fine model using water flooding data and utilizing pseudo functions data. The resulted cases as well as the fine model were then taken to prediction to estimate the performance of three-phase flow of gas and WAG processes. Result so fine and coarse models were then analyzed and compared to draw conclusions on the reliability of the coarse models to match the predicted results of the reference model of the fine simulation model.;The application of assisted history match (Automatic History Matching) was examined successfully in this project as a tool to identify the range of uncertainty parameters that are impacting the reservoir performance. A combination of manual and assisted matching, few realizations of acceptable history matched models were produced. This is to determine the effect of reservoir different reservoir parameters on the process.;Prediction results showed differences between fine grid and coarse grid models performances. The upscaled models utilizing pseudo functions were able to predict the water performance only within the uncertainties of history matching. Unlike water, Gas performance was not predictable by the upscaled models. By comparing fine model and coarse models gas behavior, it was concluded that 3-phase flow cannot be accurately predicted with 2-phase flow models where the main reason is the absence of the gas during history.