A controllable gas-lift well having controllable gas-lift valves and sensors for detecting flow regime is provided. The well uses production tubing and casing to communicate with and power the controllable valve from the surface. A signal impedance apparatus in the form of induction chokes at the surface and downhole electrically isolate the tubing from the casing. A high band-width, adaptable spread spectrum communication system is used to communicate between the controllable valve and the surface. Sensors, such as pressure, temperature, and acoustic sensors, may be provided downhole to more accurately assess downhole conditions and in particular, the flow regime of the fluid within the tubing. Operating conditions, such as gas injection rate, back pressure on the tubing, and position of downhole controllable valves are varied depending on flow regime, downhole conditions, oil production, gas usage and availability, to optimize production. An Artificial Neural Network (ANN) is trained to detect a Taylor flow regime using downhole acoustic sensors, plus other sensors as desired. The detection and control system and method thereof is useful in many applications involving multi-phase flow in a conduit.