A Well Temperature Correction Based on the Least Squares Method and Its Application in a Coal Mining Area, China

With the increase in mining depth of coal resources, high-temperature thermal damage has become increasingly prominent, and research on geotemperature in mining areas has received increasing attention. At present, simple temperature measurement is the most commonly used well temperature measurement method, but the obtained data cannot be used directly and need to be corrected. According to the thermal recovery law of an approximately steady-state hole, the “three-point” method is often used to correct simple well temperature data. However, the calibration work is complicated, time-consuming and laborious. Moreover, in the “three-point” method, the well depth and the time from when the well fluid stopping circulation to the temperature measurement (TSC) are not considered enough, which easily leads to deviations in the well temperature correction results. Based on the TSC and well depth, a simple well temperature correction equation was obtained by using 50 available data points with TSCs less than 20 h of approximate steady-state temperature measurements collected in the Huainan coalfield (TSC < 20 h in the general simple temperature measurements). The fitting effect of the equation was verified with the original ground temperature and geothermal gradient; in its application to the Huainan coalfield geothermal field, the model has achieved an ideal effect.