Underground gas storage (UGS), as a key component of natural gas pipeline network, can not only be used as emergency gas source under pipeline system failure situation, but it is also available for seasonal peak shaving under pipeline system normal situation. Therefore, in order to meet the natural gas needs, it is of vital importance to safeguard the security of UGS operation and assess the reliability of UGS. The aim of the overall study is to develop an integration method for assessing operational reliability of UGS in depleted reservoir under different injection-production scenarios whereas existing studies only assess single component or subsystem reliability. According to function zoning, UGS is separated into reservoir, well system containing multiple injection/production wells and surface system, and reservoir and surface system are connected through well system. At the first step of reliability assessment, the hydraulic calculation including gas injection process calculation and gas production process calculation is adopted to obtain the operation parameters of each component in UGS. Next, reliability of reservoir, injection/production well and equipment in surface system are evaluated using operation parameters and Monte Carlo approach. The reliability of subsystem, such as well system and surface system, are then calculated according to system reliability theory. Finally, operational reliability of UGS is obtained, which reflects the capacity of performing gas injection-production function. Two test cases are given to illustrate the integration method.
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