New developments in the gas first fill operationof natural gas storage caverns

The first-fill of natural gas storage caverns involves simultaneous gas injection and brinedisplacement. With the standard completions used for this purpose in Europe, this operation cansometimes take more than a year depending on the size of the cavern. This length of time is largelyattributable to the need to subsequently snub the brine displacement string under pressure, and themandatory stipulation to install a safety shut-off valve. The first-fill time can however besignificantly reduced by departing from the use of standard completions, and especially byinstalling a bigger debrining string. The benefits and risks of this advancement depend onparameters such as cavern size, height and pressure range. Constraints also involve the capacitiesof the gas supply, brine disposal, gas compressors and brine disposal pumps, as well as limits to theflow velocities of gas and brine. Modifications have to be compatible with the existing gascompletion system of the cavern, and must guarantee conditions for safe snubbing operations.The paper presents the conventional gas first fill process in comparison to the newdevelopments. Based on practical experience with this new development, significant time savings,and therefore earlier commissioning of the cavern can be reported. The technical and economicaspects are also discussed

Keywords:

Underground storage in salt formations , Natural gas storage , Gas first fill , Gascompletion for salt caverns