Behind casing water volume flow rate measurement using gamma ray spectral degradation
 Measurement of the distance from a gamma ray detector to a gamma ray source for locating of a channel of undesired behind casing water flow in a producing well is provided. A relationship is given for the count rate ratio at a detector in two distinct energy regions of the gamma ray spectrum as a function of the distance from the gamma ray source. When counts of characteristic gamma rays due to the decay of radioactive nitrogen 16 produced by the activation of elemental oxygen nuclei comprising the molecular structure of undesired water flow are made then the distance R to such flow may be determined by means of the above relationship. This may then be interpreted in terms of the volume flow rate V of the undesired water flow. 
Texaco Inc.
G G E G
G01V G01F E21B G01F
inventional inventional inventional inventional
Hans J. Ward E. Harry D. Dan M.
Paap Schultz Smith, Jr. Arnold