TRACER PLACEMENT TECHNIQUES FOR IMPROVED RADIOACTIVE TRACER LOGGING.

The accuracy of a radioactive tracer log depends on the way in which the tracer is introduced into the wellbore and how it mixes and disperses in the wellbore fluid. We have conducted experiments in a model wellbore to determine the factors affecting tracer slug distribution and their resulting responses at tracer detectors. The tracer placement parameters studied included tracer shot velocity, shot duration, and wellbore flow rate. In addition, the viscosity of the tracer was varied to determine if this would decrease the dispersion of the tracer slug. A blue dye was used as tracer and two detectors downstream of the injection point measured tracer concentration based on the attenuation of light passing through the clear pipeline. Tracer slugs were also videotaped to determine their distribution across the wellbore. It is clear that radioactive tracer log quality can be significantly improved by using the newer logging tools that allow for careful control of shot duration. With a few test shots in the upper part of the wellbore, optimum tracer placement techniques for a given well can be determined.

TRACER PLACEMENT TECHNIQUES FOR IMPROVED RADIOACTIVE TRACER LOGGING. Conference Paper