The calculated distance (air line) between Khorramshahr and Ar Riqqah is approximately 90 miles respectively 144 kilometers.
By car or train, the actual journey to Ar Riqqah is certainly longer, as only the direct route (as the crow flies) between Khorramshahr and Ar Riqqah has been calculated here.
Air line (approximately)
144 kilometers
78 nautical miles