Adaptive Multiscale-streamline Simulation and Inversion for High-resolution Geomodels

First, we present an efficient method for integrating dynamic data in high-resolution subsurface models. The method consists of two key technologies: (i) a very fast multiscale-streamline flow simulator, and (ii) a fast and robust 'generalized travel-time inversion' method. The travel-time inversion is based on sensitivities computed analytically along streamlines using only one forward simulation. The sensitivities are also used to selectively reduce the updating of basis functions in the multiscale mixed finite-element pressure solver. Second, we discuss extensions of the methodology to grids with large differences in cell sizes and unstructured connections. To this end, we suggest to use rescaled sensitivities (average cell volume multiplied by local sensitivity density) in the inversion and propose a generalized smoothing operator for the regularization to impose smooth modification on reservoir parameters. Two numerical examples demonstrate that this reduces undesired grid effects. Finally, we show a slightly more complex example with two faults and infill drilling.