An optimization model for managing compressors in salt cavern gas storage

Abstract

In light of the upcoming gas market liberalization, the storage in underground gas stor‐ age should be treated as a commercial activity, providing profit to investors. Gas fuel con‐ sumed for the operation of underground gas storage facility, mainly by work of compressors injecting gas into storage, will have to be carefully accounted and bought at market prices. In a competitive gas market, technical and economic optimization of the underground gas storage operation takes on particular significance. Liberalized market requires that the under‐ ground gas storage operator manages the operation in the most efficient way, affecting the profitability of service storage provision. Optimization of operation of underground gas storage in salt cavern (CUGS) is an im‐ portant operational problem in CUGS management. Despite many works on this subject [6, 16, 17, 20], it is not totally resolved. The reduction of gas storage capacity in a bed of rock salt, called convergence is inevitable, but its size also depends on the cavern depth and the operating storage [5, 19]. Operation practice suggests that the first step is to inject a large cavern convergence, then the lower and finally the shallowest cavern lying. In the withdraw process, the situation is reversed. However, the optimization that takes into account only the speed of storage caverns convergence is not ideal. You may find that maintaining a regime of operation that minimizes the effect of reducing the volume of the storage spaces can increase the cost of the gas installation (surface infrastructure). It is because Injection of the gas to the deepest caverns requires more power compressors. This occurs in CUGS Mogilno where the system can transport up to 400,000 standard cubic meter per hour [SCm/hr] of natural gas which about 2% is used by the compressor sta‐ tions to inject gas into storage caverns. It is estimated [13] that the global optimization of the