The accurate prediction of shale oil production requires strong coupling between flow and geomechanics. However, traditional models often overlook the dynamic permeability damage induced by in-situ stress variations. To address this issue, our study establishes a fully coupled numerical simulation framework based on the virtual element method. This framework directly employs unstructured polyhedral grids generated by geological modeling software. This approach provides a distinct advantage over conventional methods, which rely on mesh reconstruction and exhibit severe distortion problems under large deformations. The model is validated using production data from a real field block, demonstrating the ability to accurately reproduce complex flow regime transitions and stress-induced production decline. Quantitative analysis identifies the Biot modulus as a key parameter governing reservoir stress sensitivity. Lower modulus values directly lead to substantial and sustained permeability damage. High fracture conductivity provides an initial productivity enhancement; however, it also accelerates stress redistribution around fractures that can cause severe localized permeability impairment in the vicinity of fracture roots over a relatively short production period. This work establishes a new integrated simulation model that couples geomechanical feedback with fluid flow, providing a quantitative engineering basis for effectively optimizing pressure-controlled production strategies and hydraulic fracturing design in shale oil reservoirs.