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Underground Injection Conrrol Branch Guidance No. 5 ' • wYSj wyg://35/h~ ip://w ww.e pa.go v/reg5oh2o/u idr5_O5. h tm 6. Follow the slug with the logging tool or make repeated passes upward through the slug as i moves down the well. Any increase in radioactivity which remains behind the slug should I investigated by supplementary passes through the interval as needed to determine whether a result of material adhering to the tubing or of a leak. All logging should be done at a sing logging speed which is appropriate for the injection rate to allow quantitative measurement deflections to be evaluated 7. If repeated passes are used, the logs resulting from the slug-tracking exercise should overly that the return of radioactivity to the level which existed before the slug's passing is demonstrated for the entire length of the section of the well being tested. The logs of all pa: should be presented as a composite log on a common depth track. If means to differentiate log [races are available no other presentation is required. If the traces cannot be differentia[ on [he composite log, they should also be presented individually; 8. After any ejection, the slug should be followed until it has moved below [he interval being tested. If the slug splits, both slug portions must be accounted for. This can be accomplishe concentrating first on the upward moving portion, and resuming [racking of the downward moving slug after the upward moving slug is tracked to its final destination; and 9. After completion of the passes, a final log should be made through the entire tested interva check for residual radioactivity which might be associated with exit of tracer material from well bore. If the tubing has been removed from the well and the casing is being tested, leaked RA material v exit the well bore into a porous, permeable zone or Fracture or move along the well bore to a port permeable zone or fracture. The movement of the tracer should be followed and the depth at whit exits the well bore recorded. Leaks in the casing can be located with the tubing in the well by monitoring for upward movemel the base of the tubing with the packer released, as described in Attachment 8. Except in the unlikt case that the pressure in the aquifer with which a leak allows communication is higher than [he injection pressure at the same depth less the friction loss from the leak to the end of the tubing, at absence of upward movement when the top of the annulus is sealed, means that there is no leak it casing. However extreme caze must be taken to ensure that upward movement will be identified. release of alonger-period slug may increase the strength of the upward moving slug. Any upward movement of RA tracer will continue until the tracer reaches the leak and exits the well bore. If the operator wishes, the portions of the injection interval which accept waste may be determine making more frequent passes while the slug is within the injection interval. The sensitivity may b reset so that the log trace remains on scale. E. Interpretation 1. Where a measurable amount of RA tracer material leaks from the tubing, it will be observe a small area of increased radioactivity after [he slug has passed; 2. If an area of elevated radioactivity is observed, additional runs should clarify what become; the RA material responsible. This will demonstrate whether only the tubing is leaking, or b the tubing and casing lack integrity. In most cases, if a well's casing has integrity but a tubi. leak exists, pressure equalization and cessation of leaking will occur until a change in injec IS of 34 5/?g/99 1:09 PM