it is also possible to pump another fluid than the treatment fluid on its own in order to achieve the required down hole injection temperature for instance if it is estimated that under the conditions under consideration the down hole injection temperature may not be controlled by pumping the treatment fluid another fluid may be pumped at some stages in order to achieve the required down hole injection temperature for some time and to allow more accurate interpretation for instance at the end of an acid treatment a gas may be pumped after the acids to achieve a larger change on the down hole injection temperature this larger change on the down hole injection temperature will allow a more accurate interpretation concerning the event associated with the gas injection which may be a direct consequence of the treatment performance for instance after having pumped the acid the inflow profile along the well is what determines the acid treatment performance pumping a gas after the acid with an optimum down hole injection temperature will reveal the inflow profile during gas injection the inflow profile during gas injection being a consequence of the performance of the acid the acid performance may be estimated after pumping the gas the pump rate is set to zero and the well is.