Gamma Ray and Collar Logs are used to correlate our depth measurements back to the original open hole and cased hole logs that were run during well completion. It is imperative that we have a copy in the field during our test.
One serious trap to avoid is the "here's the last log we ran" syndrome. Correlating gamma ray logs that were run with various types and sizes of detectors is a bit of an art. It is not unusual for a correlation to be off by 1 to 3 feet. This is acceptable for most production logging tests. However, if you are correlating to the 5th in a series of logs, you may be as much as 10' to 15' off depth. Always try to use the original open hole logs or the logs used to perforate the well.
Annulus TRAC-III Page
Cardinal Welcome Page