A computer-implemented method for generating a near-well unstructured grid, the method comprising: receiving, by one or more processors, input data, the input data comprising: a structured geocellular model having a well or a structured reservoir simulation model having a well; and well trajectory data and completion data for the well; determining, by one or more processors, a field polygon based on the input data; determining, by one or more processors, a reservoir polygon having a region of interest containing the well; generating, by one or more processors, a plurality of grid points, wherein generating the plurality of grid points comprises a plurality of multi-level quad-tree local grid refinement, LGR, grid points, the plurality of grid points further comprising: a plurality of field grid points based on a user-specified field grid size; a plurality of reservoir grid points based on a user-specified reservoir grid size for each reservoir; a plurality of well grid points based on a well grid size; and a parallel track of a plurality of near-wellbore grid points on both sides of each of the plurality of well grid points based on the well grid size; performing conflicting point removal and point adjustments to generate a plurality of final grid points based on a point prioritization of weights assigned to the plurality of grid points, wherein the plurality of near-wellbore grid points are weighted higher than the quad-tree refinement points but below the plurality of well grid points; performing, by one or more processors, a Delaunay triangulation based on the plurality of final grid points; generating, by one or more processors, a Voronoi grid based on the Delaunay triangulation; generating, by one or more processors, a near-well unstructured grid based on the Voronoi grid, the generating comprising: generating a geometry of the near-well unstructured grid; generating properties of the near-well unstructured grid; and generating perforation of the near-well unstructured grid; providing, by one or more processors, the near-well unstructured grid to a parallel reservoir simulator; and performing a reservoir simulation of the near-well unstructured grid via the parallel reservoir simulator. receiving, by one or more processors, input data, the input data comprising: a structured geocellular model having a well or a structured reservoir simulation model having a well; and well trajectory data and completion data for the well; a structured geocellular model having a well or a structured reservoir simulation model having a well; and well trajectory data and completion data for the well; determining, by one or more processors, a field polygon based on the input data; determining, by one or more processors, a reservoir polygon having a region of interest containing the well; generating, by one or more processors, a plurality of grid points, wherein generating the plurality of grid points comprises a plurality of multi-level quad-tree local grid refinement, LGR, grid points, the plurality of grid points further comprising: a plurality of field grid points based on a user-specified field grid size; a plurality of reservoir grid points based on a user-specified reservoir grid size for each reservoir; a plurality of well grid points based on a well grid size; and a parallel track of a plurality of near-wellbore grid points on both sides of each of the plurality of well grid points based on the well grid size; a plurality of field grid points based on a user-specified field grid size; a plurality of reservoir grid points based on a user-specified reservoir grid size for each reservoir; a plurality of well grid points based on a well grid size; and a parallel track of a plurality of near-wellbore grid points on both sides of each of the plurality of well grid points based on the well grid size; performing conflicting point removal and point adjustments to generate a plurality of final grid points based on a point prioritization of weights assigned to the plurality of grid points, wherein the plurality of near-wellbore grid points are weighted higher than the quad-tree refinement points but below the plurality of well grid points; performing, by one or more processors, a Delaunay triangulation based on the plurality of final grid points; generating, by one or more processors, a Voronoi grid based on the Delaunay triangulation; generating, by one or more processors, a near-well unstructured grid based on the Voronoi grid, the generating comprising: generating a geometry of the near-well unstructured grid; generating properties of the near-well unstructured grid; and generating perforation of the near-well unstructured grid; generating a geometry of the near-well unstructured grid; generating properties of the near-well unstructured grid; and generating perforation of the near-well unstructured grid; providing, by one or more processors, the near-well unstructured grid to a parallel reservoir simulator; and performing a reservoir simulation of the near-well unstructured grid via the parallel reservoir simulator.