Research On Characteristic Of The Seepage Of Gas Caverns In Layered Salt Rock Based On Coupled Fluid-solid Theory

Salt rock is a kind of soft rock, with compact structure, low porosity, low permeability, and good creep behavior and damage character such as self-healing. In China, the salt rock has several weak interlayers, the characteristics of single thin layer. These compared with foreign big and thin salt dome are different. Gas permeability mechanism for the laminated salt rock gas storage is very complex. It is key problems to establish the permeability mechanical model and to put forward corresponding numerical method which is suitable for salt rock with weak interlayer. In this paper, combining with the results of previous scholars, seepage is taken into consideration. In the process of calculation, the permeability and porosity change constantly.(1) When using the model of PWIPP for fluid-solid coupling calculation, fluids will expand the scope of plastic zone around the gas storage. In addition, the fluid will also be different influence on damage variable under different internal pressure.(2) Using the models of PWIPP and userc_d, the numerical simulations are carried out. The behavior of the salt rock cavern under the both situation is different in the seepage scope. Because the influence of the damage variable to permeability is greater, so the seepage scope of the model of userc_d is bigger than the other.In previous studies, the permeability and porosity of seepage are set to a certain value. In this paper, we realize the dynamic evolution of permeability and porosity. There are two innovation points.(1) The seepage analysis of viscoelastic plastic gas caverns in layered salt rock, we realize the dynamic evolution of permeability and porosity with permeability theory. We verify the validity of the numerical simulation at the same time.(2) The seepage analysis of damaged gas caverns in layered salt rock, we realize the dynamic evolution of permeability and porosity with permeability tests.