Abstract: Herein disclosed are methods and systems related to processes for injection wells generally utilized in the oil and gas industry. The methods herein include a method of estimating the relative cumulative volume of fluids injected into multiple zones of an injection well located in a hydrocarbon reservoir, the injection well including a plurality of zones. The method comprises injecting fluid into a wellbore of the injection well. The method further includes measuring temperature at points along the wellbore to produce a warm-back data set that includes data for a plurality of times and depths. The method also includes modifying an initial geotherm using only data from the warm-back data set that is in a middle-time region (MTR) of the warm-back data set to produce a calculated pseudo-geotherm. The calculated pseudo-geotherm may be used to estimate a volume of fluid injected into each of the plurality of zones.