Determination of Injection Interval and Profile from Temperature and Pressure Surveys on a Gas Injection Well
Authors: McInroy S.H. , DeLong T.W. 
Published: December 2007

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Abstract
The use of temperature surveys for locating the actual intervals of injection and the injection profile within these intervals in a gas injection well has not been widely recognized. This paper presents the results of a number of rather comprehensive surveys for these purposes. Pressure surveys were used primarily as back-up data for the temperature surveys. A temperature bomb of the type normally located in the field, and owned by the operating company, was found to be satisfactory. Continuous temperature surveys, obtained by synchronizing depth measurements with time, using a stop-watch, were much faster than bench-type surveys and produced much better detail.
It was found that injecting temperature surveys may be successfully used to locate the actual injection interval in a gas injection well. Shut-in temperature surveys, in conjunction with the injecting surveys may be used to calculate the injection profile, i.e., per cent of total injection/ft vs depth.

Introduction
In May, 1964, Marathon Oil Co. became interested in determining the actual injection interval of a gas injection well. After eight months of operations, none of the injected gas had appeared in any of the producing wells. Consequently, there was no way of knowing where the injected gas was migrating to in the reservoir. Consideration was given to perforating one or more of the producing wells to if injected gas existed behind the casing. Since a 122-ft open-hole section existed in the injection well, it was necessary to know the interval actually taking gas in order to locate the intervals to perforate in the producing wells. After reviewing the various techniques used or being considered by the industry, it was decided to try to locate the injection interval with temperature surveys. Pressure surveys for fluid level determination were to supplement this procedure.
It was also hoped that an estimate of the gas injection profile, or per cent injection rate vs depth, might be obtained from the temperature surveys. A gas injection profile would provide information on the vertical sweep efficiency of the reservoir. Vertical sweep efficiency has been considered to be a possible cause of low oil recovery from this particular reservoir.