For about thirty years from early 1970s, Korea has constructed many large-scale underground energy storage caverns in response to the rapid industrial development. In this period, rock mechanics engineers in Korea gained valuable experiences in the area of underground space technologies. Rock mechanics and rock engineering played an important role in design and construction of underground oil and gas storage projects. In this paper, we briefly review the underground oil and gas storage projects completed in South Korea and some related research works published by authors for ten years from 1990 at Rock Mechanics and Rock Engineering Laboratory, Seoul National University. These research works include the mechanical and hydrological, stability analyses of the storage caverns by using a finite element method, back analysis, rock block analysis, and fracture network analysis.
Korea is ranked 109th in the world in terms of area and about 70 percent of the territory is mountainous regions. It is, however, ranked 25th in population and 13th in gross domestic product (GDP) as of 2014. With regard to energy consumption, Korea is the 6th largest crude oil importing country and the 9th for oil consumption. It is also ranked 10th for electricity consumption in the world.
Korea built many large-scale underground energy storage caverns in a relatively short period of time. Construction of such underground facilities for crude oil and liquefied petroleum gas (LPG) was stimulated by the rapid industrialization of Korea and two oil crises in the 1970s. The engineers of rock mechanics have played key roles in the construction projects: for site investigation, designing, and construction stages, for example.
The first underground oil storage project in Korea was K-1 initiated in 1975. Several underground facilities for oil or gas storage have been successfully constructed since then. Some of those caverns – K-1, L-1, U-1, and U-2, for example, were extended for securing further storage. Above ground tanks for oil storage in Ulsan are now under way of dismantling to change into underground storage.
Not only for stable energy supplying and overcoming the adverse topography but also for environmental and safety concerns, Korea is expected to further its effort in constructing underground storage facilities, which means that rock mechanics engineers continue to develop technologies for designing and constructing advanced underground structures.
Various rock engineering topics related to the underground energy storage have been studied in Korea. In this paper, some of the topics dealt by rock mechanics and rock engineering laboratory at Seoul National University are introduced. They are based on FEM and deterministic/stochastic rock block models for mechanical stability analysis and on fracture network and elasto-plastic porous media models for hydrological stabilities analysis.