Abstract: The experiment of fluid migration is studied through staining method in the three-dimensional cavity model of salt rock gas storage， and the maximum influencing range of fluid migration is analyzed. The study results show as follows: the upper and lower boundaries of the maximum influencing range of fluid migration move towards the top of cavity with the increase of brine concentration， which facilitates the salt rock solution of the side walls of upper cavity. With the increase of water injection flow， the increase of radial migration velocity facilitates the salt rock solution of side walls， and the lower boundary of the maximum influencing range of fluid migration moves towards the bottom part of cavity， which facilitates the salt rock solution of lower part of middle tube mouth. The engineering values of the maximum influencing range of fluid migration are obtained through converting experimental values under the combined conditions of different brine concentrations (25， 50，75g/L)， water injection flows (60， 80， 100m³/h) and tubes spacing (28，42， 56， 70， 84， 98m). Research results and method can provide the reference and approach for improving cavity constructing efficiency and controlling cavity shape.

Key words: salt rock gas storage, brine concentration, fluid migration, influencing range, staining method