A Multiscale Mixed Finite Element Method for Vuggy and Naturally Fractured Reservoirs

The topic of this thesis is fast and accurate simulation techniques used for simulations of flow and transport in porous media, in particular petroleum reservoirs. Fast and accurate simulation techniques are becoming increasingly important for reservoir management and development, as the geological models increase in size and level of detail and require more computational resources to be utilized. The multiscale framework is a promising approach to facilitate simulation of detailed geological models. In contrast to traditional upscaling approaches, the multiscale methods have the detailed geological models present at all times. The work in this thesis includes development of a multiscale-multiphysics method for naturally fractured reservoirs and a new coarsening strategy for geological models to facilitate fast and accurate transport simulations in a multiscale framework. In addition, the work comprises an application of the multiscale framework for flow and transport simulation for rate optimization loops. The coarsening strategy generates flow-based transport grids and is based on amalgamating cells from a fine model, typically the geological model, according to an indicator function. The research indicates a great potential for flexibility and scalability suitable for multi-fidelity simulators