Quad-Tree decomposition method for areal upscaling of heterogeneous reservoirs: Application to arbitrary shaped reservoirs

•Quad-Tree decomposition method was employed for upscaling of 2D geological models of arbitrary shaped reservoirs.•Two challenging porous media including areal-layered and fractured were used.•Two-phase flow simulation was implemented in irregular-shaped reservoirs.•Two-phase flow simulation was implemented using unstructured computational gridblocks.•The proposed method can make a significant computation speedup while maintaining the same accuracy as the fine grid.