대전 LNG 저장 Pilot Cavern에서의 지하수 배수시스템 효율성 시험 및 평가에 대한 사례 연구

SK Engineering & Construction Company, Geostock and SN Technigaz in France have developed the conceptual model for the lined LNG underground storage tanks. In order to confirm the applicability of model for all the required techniques during construction and operation, Daejeon LNG Pilot storage cavern was constructed and operated from 2002 to the end of 2004. In this paper the groundwater drainage system which is one of the most important techniques for LNG underground storage, was evaluated by efficiency test, and was verified by comparison to the results of groundwater monitoring and numerical modeling. The results of 1st test in April 2003 showed 86% of drain efficiency. The efficiency of drainage system was not enough for the operation, so it is determined that three additional drainage holes needed. After installation of additional drainage holes, 2nd test was performed in August 2003. The drainage system could drain the groundwater more than 96%. It is confirmed that groundwater level was under the bottom of cavern by measurements with porepressure cell, piezometer and downward drainage hole which was installed around the cavern. Results of numerical model by MODFLOW showed the consistency with measured pore-pressure, groundwater level and the amount of drainage.