Progressive deformation and pore network attributes of sandstone at in-situ stress states using computed tomography

Abstract

Understanding the mechanism of microscopic failure of sandstone is exceptionally crucial for various engineering projects. The current study investigates the real-time high-resolution micro-computed tomography (m-CT) based microscopic failure attributes of sandstone under unconfined axial compression. Specimens of sandstone were analysed under varying loading conditions (zero load, 25%, 50%, 75% of the peak loads, and at peak failure loads) for analysing their effects on various petrophysical properties such as total pores, connected pores, non-connected pores, development of microfractures, and different pore network attributes such as pore radius, pore-volume, pore coordination number (CN), throat radius and throat channel length. Such an investigation enables us to explore the evolution of failure within sandstone under in-situ compression. The results showed the appearance of macrofractures and an increasing pattern of various pore-network attributes in the sandstone after 50% of the peak load. However, the non-connected pores gradually decreased with the rising loading stages. Finally, a negative correlation was obtained between tortuosity of sandsone with effective porosity and coordination number.