Damage Analysis of Sandstone During the Creep Stage After High-Temperature Heat Treatment Based on NMR Technology

Based on nuclear magnetic resonance (NMR) technology, the effect of sandstone creep behaviors on porosity is analyzed. Through quantitative analysis of NMR parameters, the distribution of pores of sandstone samples treated at different temperatures during the creep stage is investigated. Moreover, the creep damage mechanism of sandstone is studied by combining the change characteristics of the porosity and the characteristics of creep deformation of sandstone sample during the creep stage. The results show that the creep behavior of sandstone samples promotes an increase in porosity, and the temperature also promotes an increase in the porosity of sandstone during the creep stage. The larger the loading ratio, the more sensitive is the incremental value of porosity to temperature, and the greater is the effect of temperature on creep damage of sandstone samples. When the loading ratio is small, the percentage of micropores decreases and the percentage of macropores increases as the loading ratio increases. However, when the loading ratio is large, the percentage of the micropores increases and the percentage of the macropores decreases as the loading ratio increases. In addition, as the temperature increases, the ductility of sandstone samples increases. Temperature can promote the deformation of sandstone samples during the creep stage, and the effect of temperature on the creep strain is more obvious at high stress levels.