Study On The Law Of Fluid Convection And Diffusion In The Construction Of Salt Cave Gas Storage

The underground gas storage is an important and indispensable part in the natural gas industrial chain. The salt rock characterized by low permeability, good creep behavior and mechanical stability is qualified enough for underground gas storage. According to the geological characteristics of salt stratum in China, better understanding of the theory, technique and technology of salt-cavern gas storage designing and construction contributes to promoting development and operation of salt-cavern gas storage in our country.In this paper, the main focus is based on analysis of dynamic characteristics of the flow field in salt-cavern gas storage. Theoretical analysis and numerical simulation have been conducted on the basis of the relative theory of fluid dynamics and chemical kinetics. The mathematical model of solution mining cavern has been built according to water dissolving mechanism. Using CFD software Fluent, the cavity numerical model has been built and the influence of the geometry of dissolution cavity, injection-production parameter and the location of interlayer on the fluid convective diffusion mechanism have been analyzed. The numerical simulation results provide a reference to the construction of salt-cavern gas storage.The main contributions in this thesis are as follows:1. The study of water soluble mechanism in salt-cavern gas storage has been created based on the basic principles of fluid dynamics and chemical kinetics; the mathematical model and numerical model of salt-cavern gas storage have been established.2. Using normal circulation method to inject water into the cavern kerve, the distribution of fluid velocity vector field and the concentration field in the dissolved cavity are analyzed by taking into account different center tube position and using fluent computing software. The results indicate that improving the center tube will reduce the intensity of fluid motion and salt karst erosion rates.3. Using reverse circulation method to inject water into the main cavern, the distribution of fluid velocity vector field and the concentration field in the dissolved cavity are analyzed by taking into account different intermediate tube position and using fluent computing software. The results indicate that improving the intermediate tube will reduce the intensity of fluid motion and salt karst erosion rates.4. Considering the different length of interlayer, different distance between the inter-medium tube and central tube, the different water injection rate and the different number of interlayer, the distribution of velocity field and the stress of the interlayer have been simulated. The results show that the change of interlayer length and water injection speed mainly affect the intensity of the flow field. And changing column spacing and the number of interlayer mainly affect the distribution of the flow field.