Implications of rootless geothermal models: Missing processes, parameter compensation, and imposter convection

•Models of heat and mass in geothermal reservoirs commonly represent the upper part a deep convecting system and simplify the deep region to a boundary.•All choices of boundary condition can misrepresent aspects of the overall system, including essential processes like convection.•Parameters can take unphysical values to compensate for incorrect physics, affecting model calibration and biasing forecasts.•Forecast models must account for these simplifications.