Abstract: A method and apparatus for monitoring conditions in a fluid flow path so that the composition and operation of the flow path can be determined is disclosed. The apparatus includes a fluid flow detector, such as a gas flow logging tool, which detects the velocity at which a fluid, such as a gas, flows along the fluid flow path, such as a gas injection conduit used in a gas lift program for extracting oil from a well. The monitoring apparatus also includes a pressure detector and a temperature detector. Each of these detectors provides a respective electrical signal to a recorder unit, such as a strip chart recorder, for creation thereby of respective logs. The logs generated by the recorder unit permit qualitative and quantitative analyses of identifiable fluid flow path phenomena, such as the locations of valves and the volumetric flow of the fluid, to be made.