TX 75083-3836, U.S.A., fax 01-972-952-9435. AbstractThe already complex job of diagnosing production problems and flow profiling in a multiphase environment is further complicated by the complex flow regimes encountered in horizontal, highly deviated, and slim wells. Accurate holdup measurements are needed to clearly identify the first point of hydrocarbon or water entry, and independent oil, water and gas flow rates versus depth are needed to obtain overall downhole flow rates and to identify production from each perforated interval. Qualitative fluid identification is also needed to help determine the type of fluids contributed by each zone. Finally, imaging of the well bore is needed to detect cross flow, circulating flow, and phase segregation.