Hydrocarbon wells and methods of interrogating fluid flow within hydrocarbon wells. The hydrocarbon wells include a wellbore and downhole tubing that defines a tubing conduit and extends within the wellbore. The hydrocarbon wells also include an interrogation device. The interrogation device is configured to indicate at least one property of fluid flow within the hydrocarbon wells. The hydrocarbon wells also include a downhole location at which the interrogation device is released into the tubing conduit and a detection structure configured to query the interrogation device to determine the at least one property of fluid flow within the hydrocarbon wells. The methods include releasing an interrogation device at a downhole location within a hydrocarbon well and flowing the interrogation device from the downhole location to a surface region. The methods also include querying the interrogation device to determine at least one property of fluid flow within the hydrocarbon well.