6:15 PM - 7:30 PM
[HRE28-P07] X-ray CT visualization technology for CO2-EOR laboratory test
Keywords:X-ray CT, CO2-EOR, visualization, image analysis, quantitative assessment
There are three main categories of EOR (Enhanced Oil Recovery); thermal recovery, gas injection and chemical injection. In particular, CO2-EOR, one of the gas injection method is a technique which has attracted attention of many new markets among EOR technology.
We developed an experimental system in which the CO2-EOR laboratory tests and X-ray CT visualization can be performed simultaneously using a rock sample. The experimental system is intended to quantitatively evaluate whether there is an effect on CO2-EOR for the rock sample. Berea sandstone (diameter: 35mm, length: 80mm) were used for this experiment. The experiment was carried out under conditions that simulate the temperature and pressure of the underground; confining pressure 12MPa, pore water pressure 10MPa and temperature 40℃. Injection of the fluid was controlled by a high-precision syringe pump. In addition, specially designed high-pressure vessel to X-ray transparent was utilized for X-ray CT visualization. Porosity of the rock sample determined by X-ray CT image was about 20.21%, which is consistent with the porosity obtained in the previous test by the saturated immersion method. The sample has been saturated with KI aqueous solution, and then mixed with oil (KI-Oil mixed state; oil saturation rate 58.50%). The CO2-EOR test was carried out until the CO2 injection reaches 2PV (pore volume), finally, about 66.10% of the oil recovery rate was confirmed. Figure 1 shows a CT image when the CO2 injection amount reaches the 0.25PV.
In this study, the CO2-EOR laboratory test of porous sandstone and X-ray CT visualization were carried out to obtain the porosity, fluid saturation and oil recovery rate. We report the experiment method and results in detail. This study is expected to contribute to the development of CO2 injection methods for efficiency improvement of CO2-EOR (for example, micro-bubble CO2-EOR).