Reference no: EM133102336

For this task, you are required to paraphrase the following excerpts:

Experimental Setup and Procedures In this work, three-part experiments were conducted. First, the microscopic mechanisms of supercritical carbon dioxide (ScCO2) to the formation, including nuclear-magneticresonance (NMR) test, X-ray-diffraction (XRD) analysis, and scanning-electron-microscope (SEM) experiments were used to systematically analyze the effects of CO2 on pores and rock minerals. Second, the high-pressure chamber-reaction experiment was conducted to study the effect of ScCO2 on the crude-oil characteristics, and then the distribution and existence state of ScCO2 in the multiphase fluid during the full-cycle fracturing process were analyzed using the experiment results and multicomponent simulation. Finally, four injection modes of ScCO2- or slickwater-injection experiments were designed to compare the pressure increase, production enhancement, and flowback efficiency, and then to optimize the optimal ScCO2-injection mode and the optimal injection amount of the ScCO2 slug. Reaction Experiments of ScCO2 and Formation Structures The steps of our process are as follows.

1. The core samples were washed with Soxhlet extraction and left to dry at 80°C for 24 hours.

2. Core physical parameters such as permeability, porosity, and diameter were measured. As shown in Fig. 2, the cores were cut into thin sections with a length of 0.8 cm and a diameter of 2.5 cm, then dried at 80°C for 24 hours. The pore structure was tested by SEM and the mineral composition was tested by the XRD method.

3. We vacuumed the core samples for 6 hours and saturated them with formation water in the core holder. Then, we pressurized the core holder to the formation pressure of 25 MPa for 12 hours. The pore-size distributions were measured using the NMR instrument.

4. The core samples were placed in the high-temperature/high-pressure accumulator. CO2 was pumped into the accumulator and pressurized to the pressure of 25MPa. The accumulator was placed in the oven and the temperature was raised to 60°C to allow the core to fully interact with ScCO2 for 5 and 10 days.

5. After the preceding treatment, we put the core samples into a drying oven and dried them at 80°C for 24 hours. The pore structure and the mineral composition of the core samples were again tested with SEM and XRD. The core samples were pressurized with saturated formation water for 12 hours and the pore-size distributions were measured again using the NMR test to analyze the effect of ScCO2 on the formation structures.