Study on Sealing Integrity Mechanism of Salt Cavern Hydrogen Storage Under Alternating Load

Abstract

ABSTRACT The sealing integrity of salt cavern hydrogen storage is an important technology and safety index of hydrogen storage. In the process of injection and production, the surrounding rock of hydrogen storage chamber is in the state of alternating load stress, and there is the risk of fatigue failure and leakage. Analysis of dynamic rock mechanics characteristics of surrounding rock of salt cavern hydrogen storage chamber under alternating load is the key to study the sealing integrity mechanism of salt cavern hydrogen storage chamber. Uniaxial tests, triaxial tests, cyclic loading and unloading tests and creep tests were carried out on rock samples from salt layer, interlayer and cap layer of hydrogen storage reservoir of Jintanmao 17 well by means of rock mechanics experimental machine RTR-1500. The deformation and failure characteristics, permeability, porosity, breakthrough pressure and other parameters of rock samples under alternating loads were discussed. Based on the results of the creep test, the Burgers creep model parameters for this block were fitted. The results show that: (1) in the triaxial cyclic loading and unloading experiment, the cyclic loading and unloading before the yield point decreases the porosity and permeability of the rock sample, while the cyclic loading and unloading after the yield point increases the porosity and permeability of the rock sample.(2) In the process of cyclic loading and unloading, the dissipative energy of cap rock is greater than that of interlayer, and with the increase of cycle times, the dissipative energy first decreases and then becomes stable.(3)Burgers creep model can well reflect the creep law of salt formation in the target block, and can be used to study the long-term stability of hydrogen storage cavity. The research results provide a scientific basis for the design and operation of salt cavern hydrogen storage. INTRODUCTION Salt rock has been used in the construction of hydrogen storage because of its low porosity, low permeability and damage recovery. Sealing integrity is very important for a salt cavern hydrogen storage tank. Only by maintaining the sealing integrity of the salt cavern hydrogen storage tank can the salt cavern hydrogen storage tank run stably.