Application of Oxygen Activation Logging in Monitoring the Water Injection Effect of Carbonate Reservoirs

Determining the injection profile behind casing is a critical for the reservoir management. Conventional ILT logging only provide the intaking water in the water injection mandrel, but it is unable to identify and quantify the water flow in the complex dual completion injection wells. The oxygen activation logs provide the only method for monitoring and evaluating the injection performance behind casing. Experiments have been conducted in the field. The results show when the neutron-activation period becomes longer, the single will become wider and show stacked peak characteristics. So a shorter activation time will provide a better measurement of the flow velocity. In order to increase the magnitude of the flowing signal, longer activation time is helpful. Another experiment shows standing the instrument for a while before measuring will increase the reliability of the results. The oxygen activation techniques have been widely and successfully used in the Iraq. The examples of dual string completions demonstrate the measurement of annular injection profiles in the up and down flow and diagnosis of mechanical problems such as plug or tubing leaks.