Hydrogeological model for underground oil storage in rock caverns

For underground engineering, hydrogeological conditions of the engineering site are usually complicated, and a fine hydrogeological model is the basis for the accurate analysis of groundwater flow fields. A 3D fine hydrogeological modeling method applicable to large underground engineering was proposed in this study, which was mainly composed of data preprocessing, initial model establishment and model calibration. The modeling method adequately considers the complexity of geometric parameters and the non-uniformity of the spatial distribution of physical parameters in the geological zone. The boundaries of the model were determined based on independent hydrogeological units. The hydrogeological model is calibrated based on the monitoring data and supplementary investigation information. The 3D fine hydrogeological modeling method has been successfully applied to a large underground water-sealed oil storage engineering under construction. The groundwater level, water inflow and flow directions in four typical construction stages were used as the calibration information. Based on the fine hydrogeological model, the flow analysis was conducted to assess the containment properties of the oil storage caverns during operation. The feedback analyses of the buried depth of underground engineering and the permeability reduction ratio of the grouted zone of caverns were carried out. Through flow analyses, the complex geological conditions had obvious influence on the groundwater flow field, and the hydraulic connection between the oil storage and the river boundaries was obtained. The permeability reduction ratio of the grouted zone of caverns in this engineering was from 18% to 45%. The analysis results showed that the oil storages met the requirements of containment properties during operation. The 3D fine hydrogeological model is helpful to accurately analyze the groundwater flow field for underground engineering, and can provide scientific guidance to the design, construction and operation of underground water-sealed oil storage engineering.