Abstract: Lost circulation events are mitigated by determining a size and extent of a formation feature causing the loss of circulation. The formation feature may be determined based on surface drilling parameters, and can apply one or more of a mechanical specific energy, hydraulic, or aperture model. Using such model(s), the size of a fracture/void/aperture can be estimated and a treatment plan for a lost circulation vent can be determined. For instance, a mechanical specific energy of zero can indicate the presence of a void, the pressure at the standpipe can an extent of a formation feature, or the size of the formation feature can be estimated using drilling fluid flow rate, volume, pressure, or rheology. Determining a treatment plan can include selecting or designing a lost circulation material, a volume of lost circulation material, or alternative drilling methods.