Two geothermal wells were logged with similar wireline logs by several logging companies in a period of five years (1974-1979). The results of these equivalent logs are quantitatively different and in some cases qualitatively different. This difference also occurs between the same type of logs recorded at different time intervals by the same logging company. This paper attempts to relate and quantify these various log data when logging equip- ment has not been properly calibrated. All depths referred to in this paper for either well are from their respective kelly bushing (KB).