Impact of Second Phase Content on Rock Salt Rheological Behavior Under Cyclic Mechanical Conditions

Abstract Safe Underground Gas Storage (UGS) can be achieved in artificial, salt caverns to meet fluctuations energy demand by providing adequate knowledge on rock when subjected similar cyclic conditions. In this study, we performed mechanical tests five samples with different types and amounts of second-phase mineral content. A confining pressure 25 MPa was applied, whilst the axial stress cycled between 4.5 7.5 MPa, at 0.5 kN/s loading rate, during 48 h (7200 cycles). The results demonstrate that high content such as anhydrite layering operates a strength weakening agent accommodating larger brittle deformation comparison lower secondary minerals. This rheological behavior is further exacerbated cycling conditions recorded marked step Young’s modulus Poisson’s ratio value evolution. microstructure analysis reveals how halite grains accommodate most induced through microfracturing network development. Other structures from mechanisms are also discussed. Two new porosity observed: (i) pores around isolated crystals minerals result grain rotation under deformation, (ii) microcracks areas concentration (such anhydrite, polyhalite, carnallite, or kieserite). change has strong implications for both material its potential permeability.