Leakage path prediction model and gas tightness assessment method for gas storage salt cavern wellbores.

Rock salt cavities are commonly utilized for underground gas energy storage on a big scale due to their characteristics of low permeability and low porosity. Salt cavern wellbore leaks typically originate from depths of several hundred meters or greater beneath the Earth's surface. The intricate geological characteristics of these areas pose challenges in accurately assessing the traceability of such leaks. In this study, a mathematical model was developed to forecast the seepage path of wellbore leakage in the presence of complex geological conditions. The proposed model encompasses the resolution of equations governing the flow dynamics of cement sheath fractures. It also establishes the ontological correlation between the net pressure within micro-annuli and their geometric characteristics. The verification of the stability and reliability of the seepage mathematical model was conducted by completing cement penetration experiments carried out under different confining pressure settings and damage pretreatment conditions. The mathematical model was further enhanced to provide visualization software capable of real-time calculations for gas flow within the pore space, the extent of cement sheath debonding, and the diffusion process of pore pressure. Finally, a wellbore leakage evaluation approach for gas storage salt caverns incorporating permeability channel and pore pressure gradient is presented. [ABSTRACT FROM AUTHOR]