INTEGRATING LOCAL GRID REFINEMENTMETHODS FOR BASIN MODELING

摘要

In reservoir characterization, Local Grid Refinement (LGR) is applied routinely onrnunstructured grids for fluid flow simulation and implemented in commercial simulators.rnIn basin modeling, LGR has been recently implemented. Basin models require different andrnoftentimes more complex numerical treatment of physical phenomena than reservoir models.rnLarge numbers of cells are not feasible for basin simulators, because of excessive processingrntime. The number must be reduced by averaging properties in such a way that flow andrngeological characteristics are retained.rnPresently, tartan grids allow to refine the grid in x,y directions but waste a lot of grid cells inrnareas where refinement is neither necessary nor wanted. LGR changes substantially thernnumber of cells, allows to treat two or more imbricated Cartesian grids refining in all threernspatial directions with several levels of refinement but the regridding is done with the intent ofrnpreserving small features generated in a reservoir simulation, or of recording events at smallrnscales.rnLGR is used in situations where seismic data are available at individual structures orrnprospects but not elsewhere in kitchen areas or within the sedimentary cover. Even morernimportantly, for appraisal studies, a data set may be available at reservoir resolution that mayrnhave to be integrated with the basin scale to model the impact of basin scale fluid flow on thernreservoir.rnThe Basin LGR project has developed numerical methods that allows to treat two or morernimbricated Cartesian grids refining in all three spatial directions with several levels ofrnrefinement. Fluid flow is performed on refined grids while thermics remains on the coarserngrid. Results of the methodology are presented on a North Sea basin.