Dictionary:Temperature log

{{#category_index:T|temperature log}} A well log of temperature, often made with a resistance thermometer (thermistor). Used for locating (a) cement behind the casing (because the setting of cement is exothermic and hence raises temperature), (b) intervals which are producing gas (because the expansion of gas as it enters the borehole lowers the temperature), and (c) fluid flows (particularly behind the casing). The differential-temperature log records the difference between two thermometers which are usually about 6 ft apart; this log is especially sensitive to very small changes in temperature gradient.