Study On The Volume Strain And Mechanical Property Variation With Simulation Of Supercritical CO₂ Injection Into The High Rank Coal

Presently geological storage research is at the stage of exploration,more pilot tests are essential in basic research. This article study’s on the volumetric strain and mechanical property variation of Supercritical CO₂ Injection into the high rank coal. Based on CO₂ geological storage-enhance coalbed methane recovery system, volumetric strain property was studied under different temperature and pressure of Supercritical CO₂ Injection into NO.3 coal. Mechanism of mechanical property variation of Supercritical CO₂ was also studied by triaxial test method. The mathematical model is educed combining the experiments data and theoretic analysis. Through the positive research, this thesis gets the following conclusion:Mechanical property variation of supercritical CO₂ Injection into the high rank coal continue to rise as the increase of pressure and temperature, the expansion rate of the super-critical state is greater than the normal temperature and pressure. The experiment on samples found the limit expansion ratio can reach about 4%. The law of expansive has similar compounding laws with the adsorption.The injection of supercritical can weaken the strength of the rock structure; the strength can decrease about 28.21%.The bigger the pressure, the strength descent is obviously. Combining theory of surface energy, the adsorption caused the surface energy decrease, affecting the carrying capacity of coal and the coal will be easily destroyed.A relation of the adsorption capacity and volumetric strain was established based on the surface energy theory. By introducing the density of supercritical CO₂ this essay built a mathematical model. Comparative analysis with the result of this experiment, this model has certain applicability.