Numerical Simulation of Gas Leakage in Bedded Salt Rock Storage Cavern

Abstract

Storage of hydrocarbons in underground salt caverns created by solution mining has been commonly and successfully used for several years in developed country. Sealing performance is an important technique and safety index for salt rock gas storage. Considering the unique stratigraphic characteristics of the bedded salt rocks in China, interlayer has great influence on the tightness of salt carven. It is likely that stored natural gas will escape along the interface of interlayer. It is the key problem to establish the permeability model and to provide corresponding numerical simulation which is suitable for bedded salt rock. In the paper, based on seepage theory in porous media, evolvement equation of gas permeability is established. The salt cavern in Jintan salt mines is taken as engineering background; during the operating period, the pressure distribution and gas leak distance at interface and layers with different operating pressures are studied. It is demonstrated that the gas infiltration velocity along the damaged interface is much faster than the salt rock and mudstone interlayer, and damaged interface is the main gas leakage path. Moreover, with the bigger operation pressure, natural gas spreads much faster at the beginning years. The simulation results prove scientific basis for the design and reasonable control of operating pressure and tightness evaluation of bedded salt rock storage cavern.