Two-pulse tracer ejection method for determining injection profiles in wells

In a method of radioactive tracer logging, two slugs of tracer material are ejected. The slugs are ejected either sequentially from a single location or simultaneously from two spaced-apart locations. The distance between the tracer slugs is measured by moving a detector through the tracer slugs as they move down the borehole. The distance between the two slugs of tracer material are repeatedly measured as a function of depth, and from the measurements the amount of fluid exiting the wellbore is calculated to provide an injection profile of the well.