GAMMA CAMERA IMAGING OF WATER FLOODING PROCESS IN POROUS MEDIA USING RADIOTRACER

Tc-99m as radiotracer is used to investigate the hydrodynamics of water flooding operation inside the porous media column. Tc-99m is gamma emitter isotope with a half-life of 6 hours and energy of 0.140 MeV (90%). The porous media consists of fine sandstone with a grain size of 850 µm, kerosene as trapped oil and a layer of cement on top of the rig as the bedrock. Gamma camera is arranged next to the porous media in order to capture the movement of radiotracer which has been set to 1 minute per frame. About 1.3 mCi/0.3 ml of Tc-99m is eluted from the Molybdenum generator and injected at the upstream of the porous reactor. After injection, the addition of 3 ml of water is pushed through the system to purge the line from Tc-99m. The gamma camera gives a quantitative determination of local fluid saturations over the area of observation. Besides, Au-198 that emits gamma ray with a half-life of 2.7 days and energy of 0.41 MeV (99%), it is also used to check the compatibility of other radiotracers for water flooding activities. Thus, the objectives are to check the compatibility of radiotracers as well as to provide insights into fluid hydrodynamics (flow visualization) inside the porous media using gamma camera. The study shows that water breakthrough is recorded as 5 μSv/h after 5 minutes of continuous water flooding for and maintain at 20 µSv/h after 15 minutes where all tracer is collected at the outlet container. It is proven from this study that Tc-99m is the best water tracer for water flooding activities.