Assessment of natural containment properties of an underground crude oil storage cavern using fluid flow-stress coupling method

For the construction of underground crude oil storage caverns, natural groundwater table or artificial curtain system is employed in the cases of different geological conditions. In this study, the containment and stability properties of an underground crude oil storage cavern facility with natural groundwater table are investigated using the stress-fluid flow coupling theory. It is one of the first crude oil storage caverns being built in granite in China. The laboratory and field tests are performed to determine the volumetric deformation characteristics and seepage properties. It is indicated that the volumetric deformation characteristics are related to the shear dilatancy in laboratory tests, while there is uncertainty for the permeability in field tests. It is found that the groundwater table dissatisfies the containment requirements for the caverns under natural containment. The groundwater head required for the storage is influenced by the hydraulic gradient of underground water and the permeable properties of rock mass. There is a fractal relation between the groundwater inflow volume during construction period and the permeability of the rock mass around the caverns. During the construction period, the crown settlement ranges from 19 to 32 mm, while the horizontal convergence ranges from 16 to 35 mm. The results may benefit the construction of underground crude oil storage caverns.