Efficient Method for Estimating Groundwater Head in the Vicinity of the Underground Gas Storage Caverns in Fractured Media

Water tightness is an essential factor for the operation of underground highly pressurized gas storage caverns. To secure this tightness, the groundwater pressure must be greater than the gas pressure, and the groundwater head at a piezometer should not be lowered below the marginal head. However, various factors may affect variations in the groundwater head around storage caverns. The most influential factors are rainfall and the operating pressure of caverns. Bacterial clogging may reduce permeability and geological compaction may cause an abnormal head drop. Therefore, it is very difficult to predict the groundwater head under given conditions and find the quantitative reasons for head changes. In this study, the response function model, which explains the relationship between the groundwater head and external stresses is developed using the weighted multiple linear regression method. This model is effectively used to understand the cause of head variation in the area of underground liquefied petroleum gas storage caverns. The head difference in the observed and computed value may be used to evaluate the stability of the groundwater system.