chemical-marker injection

1. n. [Production Logging]
A technique in which a slug of material is introduced into the flowstream of a producing well to determine the flow rate of one or more of the fluids. The marker has specific properties, such as high neutron capture cross section, that allow it to be detected by sensors of a production logging tool. Some markers are specifically designed to be soluble in only one fluid phase, so that they can be used to produce a phase-velocity log. The term refers to nonradioactive markers, in contrast to the more traditional radioactive markers, or tracers.