Abstract
From a viewpoint of stable supply of gas resources, importance of natural gas underground storage has been widely recognized. Teikoku Oil (INPEX) established, for the first time in Japan in 1969, the underground gas storage (UGS) in Sekihara gas field, which was a depleted gas reservoir located a few kilometers north to Minami-Nagaoka. Since then, it has played a great role for peak shaving and/or emergency stockpile in Minami-Nagaoka gas production operation. At present, approximately 80 MMm3 of working gas is stored with the maximum deliverability of 2.4 MMm3/day.
For the purposes of increasing both the working gas capacity and withdrawal rate, delta-pressuring, operation at a maximum pressure greater than the discovery pressure associated with that reservoir, is expected for Sekihara UGS. Unfortunately, there are no experience and no regulations for “delta-pressuring” in Japan. The special measurements and the monitoring systems installed in Sekihara UGS for the safe operation of delta-pressuring are introduced in this paper.
