| Because salt's permeability is very low,and it has good creeping featurism and damage and damage recovering,it is increasingly used in building underground gas storage.However,China's salt layer has many mud interlayers,which will have some unfavorable influence on the normal operation of salt rock underground natural gas storage.Therefore,in order to ensure the long stability of salt rock underground gas storage during it's operation periods,it's very necessary to study the long stability of salt rock underground gas storage during it's operation periods.Firstly,this paper has summed up the mechanical behavior,creep behavior and corresponding creep constitutive equations,and selected applied creep constitutive equation based on the objective salt rock which has mud interlayer;moreover this paper has studied the operation pressure,salt cavity,interlayer quantity,interlayer thickness,interlayer angle and interlayer stiffness,which have some extent impact on the long stability of salt rock underground gas storage,and proposed some corresponding control measures;what's more,this paper has also studied the operation pressure,the cavity shape,interlayer quantity,interlayer thickness,interlayer angle,interlayer stiffness,pressure difference between two salt cavities and the pillar width of two salt cavities,which have some extent influence on the long stability of salt rock underground gas storage during it's operation periods,and proposed some corresponding control measures.Finally,this paper has evaluated the long stability of salt rock underground gas storage during it's operation periods,and put up some helpful suggestions for salt rock underground gas storage during building and operation periods.All in all,this paper has completed four aspect work:(1)This paper has summed up the mechanical behavior,creep behavior of salt and corresponding creep constitutive equations which salt should be satisfied with.What's more,this paper has selected corresponding applied creep constitutive equation based on the studied salt,that is cpower creep constitutive equation,and this equation has been used in numerical simulation of salt rock underground natural gas storage.(2)This paper has studied operation pressure,cavity shape,interlayer quantity,interlayer thickness,interlayer angle and interlayer stiffness of single cavity of salt rock underground natural gas storage,which have some extent influence on the long stability during it's operation periods.The increasing of operation pressure is beneficial for the decreasing of maximum displacement during cavity's creep process;the best cavity shape of underground gas storage is egg shape;the more the interlayer quantity is,the lower the resistance reformation ability of salt rock underground gas storage is,meanwhile the resistance reformation ability is closely associated with interlayer position;the more the interlayer thickness is,the higher the resistance reformation ability of salt rock underground gas storage is,however it's influence is unconspicuous;the cavity with 15° interlayer angle or so is the best stable cavity for single cavity,the soft interlayer is bad for the resistance reformation ability of salt rock underground gas storage,however the salt rock underground gas storage with hard interlayer is opposite with;and the salt rock underground gas storage with equipotent interlayer is between the above situations;in the end this paper has also proposed some relevant control measures for salt rock underground gas storage after analyzing every factor that has some impact on reformation of gas storage cavity.(3)This paper has studied operation pressure,cavity shape,interlayer quantity,interlayer thickness,interlayer angle,interlayer stiffness,operation pressure difference between two adjacent cavities and pillar width between two adjacent cavities,which have some extent impact on the long stability of salt rock underground natural gas storage group during it's operation periods.The increasing of operation pressure is beneficial for the decreasing of maximum displacement during cavity's creep process;the best cavity shape of underground gas storage group is egg shape;the more the interlayer quantity is,the lower the resistance reformation ability of salt rock underground gas storage group is,meanwhile the resistance reformation ability is closely associated with interlayer position;the more the interlayer thickness is,the higher the resistance reformation ability of salt rock underground gas storage group is,however it's influence is unconspicuous;the cavity with 12.5° interlayer angle or so is the best stable cavity for cavity group;the soft interlayer is bad for the resistance reformation ability of salt rock underground gas storage group,however the salt rock underground gas storage group with hard interlayer is opposite with,and the salt rock underground gas storage group with equipotent interlayer is between the above situations;the more the operation pressure difference between two adjacent cavities is,the more the reformation of salt rock underground natural gas storage group is,which is bad for gas storage group's long stability during it's operation periods;it is logical that the pillar width between two adjacent cavities is 2 times cavity diameter,which is beneficial for the long stability of natural gas storage group and can't waste salt layer resources;in the end this paper has also proposed some relevant control measures for salt rock underground gas storage group after analyzing every factor that has some impact on reformation of gas storage cavity.(4)This paper has comprehensively evaluated the long stability of salt rock underground natural gas storage and gas storage group during their operation periods.This paper firstly established the long stability comprehensive evaluation system based on the stability criteria of salt rock underground gas storage and gas storage group,what's more this paper has calculated every evaluation index score of gas storage and gas storage group based on those calculated maximum displacement,then the objective weigh of every evaluation index is calculated by entropy weigh method and the subjective weigh of every evaluation index is calculated by improved analytical hierarchy process method.Furthermore the comprehensive stability scores of some evaluated gas storages and gas storage groups can be calculated based on constant comprehensive weigh,variable comprehensive weigh and every evaluation index score,which can objectively gain the stability evaluation results relatively;in the end,this paper has proposed some relevantly effective suggestions and measures for gas storage and gas storage group's problems during its operation periods.The studied method and results of long stability of salt rock gas storage and gas storage group during its operation periods can provide some extent beneficial reference for salt rock underground gas storage and gas storage group's establishing and management during its operation periods. |
PDF Full Text Request