This　study　investigates　the　impacts　of　wellbore　and　skin　effects　on　co-seismic　water　level　changes.　A　numerical　model　has　been　developed　to　integrate　hydraulic　and　geomechanically　relevant　elements,　including　the　wellbore,　aquifer　system　itself　and　the　skin　zone.　In　the　model,　Darcy　flow　and　Navier-Stokes　flow　are　coupled　to　simulate　processes　in　the　aquifer　and　wellbore　consistently,　incorporating　two-phase　flow　of　water　and　gas　in　the　wellbore.　The　findings　demonstrate　the　influence　of　wellbore　and　skin　effects　on　co-seismic　well　water　oscillation,　especially　during　high-frequency　seismic　perturbations.　The　predominant　wellbore　effects　arise　from　storage　effect,　friction,　and　water　convection　in　well　screen　and　casing.　Positive　skin　decreases　the　oscillation　amplitude　and　augments　the　phase　shift,　whereas　negative　skin　displays　a　reversed　effect.　The　effects　of　wellbore　and　skin　zone　may　be　negligible　for　co-seismic　step　changes　in　well　water　levels　except　the　obstructive　effect　of　an　ultra-low　permeability　skin　zone　that　may　prevent　water　flow　into　or　out　of　the　wellbore.　This　model　contributes　to　the　understanding　of　underlying　mechanisms　affecting　seismically　induced　water　level　changes　by　incorporating　process-based　water　flow　dynamics　and　providing　an　improved　framework　for　their　analysis　and　prediction.　©　2024