A coupled flow-geomechanics model for fractured shale oil reservoirs constructed using the virtual element method

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.