Research On Characteristic Of The Seepage Of Two Gas Caverns In Layered Salt Rock

Because of low permeability,low porosity and good creep behavior and damage with self-healing character and barreid depth larger when compared with other rocks,salt rock has been the valuable object to research for the underground energy storage.But,compared with the huge and homogenic salt rock layers in foreign countries,the salt rock layers in China most contain several interlayers such as mudstone layer and gypsum layer etc.And this makes the permeability mechanism of salt rock reservoir in our country relatively complex,especially when the salt rock gas storage exists in the form of cavern groups,and the correlated problems would be more complicated and more serious.In this paper,we give corresponding analysis about the fluid-mechanical coupling principle of salt rock caverns by using the fundamental principle of rheological mechanics,damage mechanics and fluid mechanics.And build the fluid-mechanical coupling numerical model of double caverns,analysis the double caverns' characteristics by the method of numerical analysis during the process of storaging natural gas.The research conclude that the double salt rock caverns' influence law on rheological,damage and seepage by internal pressure and space between the two.(1)According to the principal of fluid-mechanical coupling,when without considering the damage factors to store energy,the volume strain of the unit in the top and middle of the cavern obviously increases,and the gas storages' seepage scope becomes large with the internal pressure increase in gradient.And the differentia internal pressure drops between the two caverns does not significantly affect their seepage scope.That can decrese the plastic ranges of the mudstone by increasing internal pressure properly within bounds.(2)Due to the great influence on the permeability of salt rock of damage factor,the numerical simulation results show that the seepage scope is larger when considering the damage factor,and the damage scope in salt rock layer become small with the incresement of the space between the caverns,but the damage value become large.It means that we can increase the internal pressure and space to diminish the damage value and scope of the caverns when compared with the single cavern.