Quantifying the containment efficiency of underground water-sealed oil storage caverns: Method and case study

Abstract

Most studies concerning the evaluation of containment property for underground water-sealed oil storage caverns have focused on containment safety. However, the water inflow into storage caverns has not been considered. Too great of a water inflow into storage caverns leads to waste in water resources and increased cost of wastewater treatment. In this study, a quantitative index of containment efficiency is proposed, which is related to both the containment safety and the water inflow into storage caverns for the safe and economic operation of underground water-sealed oil storage caverns, i.e., the degree of containment safety that can be provided by the unit water inflow into storage caverns. An evaluation method for containment efficiency is presented from the perspective of optimization of Water Curtain System (WCS) parameters and is applied to an underground water-sealed oil storage cavern. The influences of the WCS parameters and the geometric parameters of rock fractures on the containment efficiency are investigated using the Discrete Element Method (DEM). There is a nonlinear relationship between the quantitative index of containment efficiency and the WCS parameters, as well as the relationship between the quantitative index of containment efficiency and the geometric parameters of rock fractures. An evaluation of containment property for the storage cavern is conducted using the existing containment safety criterion, and the evaluation results are compared with those of containment efficiency. The rationality of the quantitative index of containment efficiency is demonstrated.