Study On The Formation Mechanism And Repairing Technology Of Irregular Salt Caverns

The current situation of China's large-scale dependence on oil and natural gas imports will exist for a long time.The deep salt mine is an ideal place for the construction of large-scale oil and natural gas reserves and compressed gas storage power stations.China is about to enter the peak period of large-scale construction of gas storage.However,in the early stage of the construction of salt cavern gas storage,a large number of irregular salt caverns that could not fully meet the requirements of the salt cavern gas storage appeared,which affected the quality of the salt cavern gas storage and also brought significant hidden dangers to the safety operation of the salt cavern gas storage.Exploring the formation mechanism of irregular salt caverns and proposing corresponding prevention and control technical measures are the urgent engineering and scientific problems to be solved at present.In response to the above problems,we investigated the typical cases of irregular salt cavern at home and abroad,and found that the formation of irregular salt caverns can be explained from the three aspects of salt mine geological conditions,salt cavern construction technology and leaching tubing accidents,built an irregular salt cavern by indoor simulation to prove the formation mechanism of the irregular salt caverns.Classifing the irregular salt caverns and further analyzing the hazards of different types of irregular salt cavern.Aiming at the various hazards of irregular salt caverns,the technical points of natural gas cushion resistance solution for repairing irregular salt cavern are summarized,including repairing mode,gas-liquid interface monitoring technology etc,and the application process of the technology was expl-ained through two on-site examples.Aiming at some unsolved key problems of natural gas cushion resistance solution repairing technology,related mathematical formulas of natural gas cushion resistance solution for repairing irregular salt caverns are derived,including natural gas cushion control(gas-liquid interface depth,natural gas cushion volume,gas-liquid interface pressure and gas injection flow)formula,water injection and brine discharge flow control formula,gas injection and brine discharge pipe string depth control formula etc.In view of some irregular salt caverns in thin layered salt layers that cannot be repaired or had poor repairing effects by natural gas cushion resistance solution technology,two retrofit repairing methods are proposed,namely,double-well horizontal cavern and triple-well horizontal cavern repairing methods.The research results provide the necessary theories and methods for the prevention and control of irregular salt caverns,which is conducive to improving the cons-truction level of salt cavern gas storage in China.