The dependence of the electronic component of thermal conductivity in a porous metal on the concentration of spherical nanocavities has been explored using multiple scattering theory. Both typical random dense packing of cavities and a fractal system of cavities were considered. In the first case, it is demonstrated that accounting for closed loops in the conduction electron trajectories significantly reduces the thermal conductivity. For the fractal system of cavities, which exhibits long-range spatial correlations, it is shown that a substantial reduction in thermal conductivity can occur at low fractal dimensions or low pore concentration.