Gas Processors Association Europe

Mike Healy, Costain Oil, Gas and Process, Manchester, UK
Costain Oil, Gas and Process has been involved in two large UK underground gas storage projects in Cheshire. The gas is to be stored in salt cavities some 600m deep, which have been leached specifically for the projects. The brine is a commercial product and the leaching process is constrained by the demands of the downstream processes.At 600m deep, the storage pressures within the caverns straddles the NTS pressure and results in gas compression being needed for injection and withdrawal during different parts of the trading cycle. The NTS gas is injected into the cavern dry, however moisture is picked up during storage and this needs to be removed before the gas is re-injected into the NTS.
The commercial and strategic reasons for underground gas storage are understood and widely reported. Some of the key design issues such as the choice of compressor, compressor driver and dehydration technology are important decisions and as they are long lead items need early decisions. Another technical area that needs special consideration is the amount of water that will be picked up in the cavern, as this sets the design for the hydrate control and corrosion control strategies.
This paper gives a brief overview of these two projects, the wider planning and environmental issues, and finally covers some project specifics