Using flow diagnostics to quantify the effects of reservoir mobility and wettability in carbonate reservoirs

This research paper explores how very fast screening methods, so-called “flow diagnostics”, can help us explore how a realistic range of geological uncertainties and model scenarios impact flow behaviours in a complex carbonate reservoir. Flow diagnostics were implemented using MATLAB® Reservoir Simulation Toolbox (MRST). MRST provides the functionality to compute approximate dynamic properties (e.g. time-of-flight) directly on the grid of the reservoir model. A synthetic but geologically realistic sector-scale reservoir model, which serves as an analogue for the Arab D formation, was used to learn and establish the flow diagnostics workflow in MRST. An analysis of the uncertainties inherent to carbonate reservoir rock typing and their effect on reservoir performance is presented along with an analysis of the impact of wettability and mobility on reservoir performance. In addition a comparison of different metrics which approximate reservoir dynamics in carbonate reservoirs is given. Testing in MRST shows that flow diagnostic simulations take negligible time (i.e. in seconds), hence a large number of model scenarios and realizations can be explored and ranked based on their dynamic behaviour. This in turn will enable us to select appropriate models for full-physics simulations that capture the full uncertainty inherent in the reservoir description.