Apparatus and tool using tracers and singles point optical probes for measuring characteristics of fluid flow in a hydrocarbon well and methods of processing resulting signals

A method of analyzing a multiphase fluid flowing in a hydrocarbon well, comprising:

• a) injecting a fluorescent tracer in the fluid, the tracer being selected from the group consisting of a water soluble tracer and an oil soluble tracer depending upon the continuous phase of the fluid;
• b) illuminating the fluid at a point downstream of the tracer injection, the point being a measured distance "d" from the tracer injection;
• c) optically detecting fluorescing tracer at or near the point of illumination;
• d) measuring the time between tracer injection and fluorescence detection.

A well production logging tool for analyzing a multiphase fluid flowing in a hydrocarbon well, comprising:

• a) an elongate tool body having means for suspending said body in the well and means for diametrically locating said body in the well;
• b) injection means coupled to a lower portion of said tool body for injecting a fluorescent tracer into the flowing fluid, said tracer selected from the group consisting of an oil soluble tracer and a water soluble tracer;
• c) a fiber optic probe having two ends, a first end being coupled to an upper portion of said tool body a measured distance "d" downstream of said injection means;
• d) a light source having a first wavelength such that said tracer will fluoresce at a second wavelength in response to illumination by said light source, said light source being optically coupled to a second end of said fiber optic probe;
• e) light detection means optically coupled to said second end of said probe, said light detection means for detecting light at said second wavelength and for providing a first output signal indicative of detection;
• and
• f) processing means coupled to said injector means and said light detection means, said processing means including actuation means for causing said injection means to inject a volume of said tracer, and timing means for measuring the time between injection of said tracer and detection of said second wavelength by said light detection means.