Stability analysis of double-cavity salt cavern storage with reasonable pillar width

Salt cavern gas storage is an important facility for storage and peak-load sheaving of natural gas. In order to analyze the effects of pillar width on the stability of double-cavity salt cavern storage, by taking Jintan Underground Salt Cavern Storage as an example, a numerical model of double-cavity storage was established with the finite element analysis method on the FLAC 3D software platform based on the deformation stability theory under the precondition of ensuring the cavity safety, improving the solution mining efficiency and maximizing the utilization ratio of salt bed. Besides, simulation analysis was conducted for the stability of the double-cavity salt cavern storage with different pillar widths, the reasonable pillar width of the double-cavity salt cavern storage was identified, and further, the change law of the maximum damage length, damage volume, nondestructive width and volumetric shrinkage of the double cavities with reasonable pillar width was studied. The results show that the reasonable pillar width of the double-cavity storage was 1.5-2.5 times of the cavity diameter in the study area. In case of reasonable pillar width, the pillar width is proportional to the maximum damage length, has little relation to the damage volume and is inversely proportional to the nondestructive width and volumetric shrinkage. Additionally, the maximum damage length, damage volume and volumetric shrinkage increase gradually, while the nondestructive width decreases with the creep time increasing. The average design pillar width is 2.0 times of the cavity diameter for Jintan Salt Cavern Gas Storage, which is within the reasonable range, and the field applications indicate that the stability model of double-cavity storage is good in reliability and accuracy.