ABSTRACT
The modelling of primary oil production and design of enhanced oil recovery operations, well log interpretation, well drilling and completion operations, and evaluation of geothermal energy resources require knowledge of the undisturbed reservoir temperature . Temperature measurements in wells are mainly used to determine the temperature of the Earth’s interior . The drilling process, however, greatly alters the temperature of the reservoir immediately surrounding the well. The temperature change is affected by the duration of drilling fl uid circulation, the temperature difference between the reservoir and the drilling fl uid, the well radius, the thermal diffusivity of the formations, and the drilling technology used. Given these factors, the exact determination of reservoir temperature at any depth requires a certain length of time in which the well is not in operation. In theory, this shut-in time is infi nitely long. There is, however, a practical limit to the time required for the difference in temperature between the well wall and surrounding reservoir to become a specifi ed small value (Kutasov and Eppelbaum 2011).
