A [[well log]] run in cased holes for the purpose of providing [[correlation]] with open-hole logs in order to establish depth control for certain completion operations. Usually the depth-control log is made with a [[radioactivity]] logging [[tool]] in conjunction with a [[casing collar locator]]. The correlation log may be a [[gamma-ray log]] and/or [[neutron log]], or in some cases a [[pulsed neutron capture log]].