Experiment Research Of Fluid Migration In Solution And Controlling To Construction Of Gas Storage Of Salt Rock

Gas storage of salt rock, as a kind of energy storage facility, is located in underground salt domes or layers and has the advantages of safety, convenience and large storage capacity, it is because of these advantages make it become an important part of national energy strategy reserves and market energy price control. Due to construction of gas storage of salt rock started late in China and has deficiencies in terms of construction technique, and the number of gas storage of salt rock operation and total energy storage can not meet need of national security and development; therefore, construction and technique research of gas storage of salt rock will be continued to develop. Water solution cavity is a key process to construction of gas storage of salt rock, in order to form a certain cavity of capacity and shape, soluble salt of main areas of water injection and fluid migration was controlled by means of adjusting water injection flow, tube and oil pad position and so on. Therefore, it is beneficial for favorable achievement to desired design of capacity and shape and improvementto construction efficiency of water solution cavity to study migration law of water injection and fluid, main region of fluid migration(impact), and study the effect of water injection, tube position and brine concentration to them.Main researches of this study concern the interrelation of fresh water into cavity, fluid migration(migration law, impact range, migration velocity), water injection flow, tube position and brine concentration in the process of water solution cavity. Main contents and results of this study as follows:(1) Three-dimensional cavity model and experimental platform are established, which are similar to gas storage of salt rock and water solution technology in engineering. Similarity criterion was established by applying the similarity model principle basing similarity theory, and the magnitude of flow,tube material were ascertained in terms of similarity criterion and geometric similarity ratio. Model cavity was made of perspex for observing flow field, and method of water injection and brine discharge are similar to them of actual engineering, hereto, the experimental preparation tasks were completed.(2) Staining method experiment of fluid migration. Dyed freshwater was injected model cavity for observing its migration results under the conditions of different water injection flows, brine concentrations, and tubes spacing in different cycle methods, results show that law of fluid migration in the positive and reverse cycle, the change of water injection flow, tubes spacing, and brine concentrations have effect on law of fluid migration, radial migration velocity,and maximum impact range. Maximum impact range values of fluid migrationwere measured under the conditions of different water injection flows, tubes spacing, and brine concentrations, which were converted to the values of actual engineering under the similar and corresponding conditions. In the positive cycle, maximum impact range values of fluid migration were obtained under the combined conditions of different water injection flows(30m3/h,45m3/h,60m3/h),brine concentrations(25g/L,50g/L,75g/L) and 14 m tube spacing; In the reverse cycle, maximum impact range values of fluid migration were obtained under the combined conditions of different water injection flows(60m3/h,80m3/h,100m3/h),brine concentrations(25g/L,50g/L,75g/L) and tubes spacing(28m,42 m,56m,70--m,84 m,98m); The function of these values can provide the reference sugges--tions to control capacity and shape of cavity and improve the efficiency of constructing cavity in water solution cavity.(3) PIV test experiment of fluid migration. The flow field vector of observation area was outputted by PIV test equipment and can visually show that most of the fluid moved upwards near the tubes,there is this phenomenon of area called buoyant plume area; however, fluid migration moved in chaotic state outside buoyant plume area, there is this phenomenon of area called free diffusion area. In the two experiments of positive cycle, average velocity0.0369m/s and 0.031m/s of observation points in buoyant plume area is greater than average velocity 0.0152m/s and 0.0162m/s of free diffusion area, so ascent motion of fluid is main and salt rock was dissolved quickly. In the two experiments of reverse cycle, average velocity 0.024m/s and 0.0193m/s ofobservation points in free diffusion area is greater than average velocity0.021m/s and 0.017m/s of buoyant plume area, so free diffusion motion of fluid is main and salt rock was dissolved quickly in the reverse cycle. The change of velocity about points was researched under the conditions of changing water injection flows and brine concentrations.(4) Numerical simulation of concentration field and flow field.Concentration field and flow field in actual engineering cavity were simulated by software of FLUENT, results show that with the increase of water injection flow, solution extents of the side walls salt rock extended gradually towards the top of cavity, and brine concentration was decreased and the velocity of salt rock dissolved was increased at the bottom of cavity side walls, so radial range of cavity was extended quickly in the positive cycle. With the increase of water injection flow, brine concentration was decreased and the velocity of salt rock dissolved was increased at the bottom of cavity side walls, and solution extents of the side walls salt rock extended gradually towards the bottom of cavity. In the positive or reverse cycle, axial length of buoyant plume area is about 20 meters, and it doesn’t change obviously with the change of water injection flows and cycle methods.