Cornegliano or How a New Porous Ugs Asset Can Rapidly Provide Multiple Services to the Grid

Summary A new Underground Gas Storage (UGS) has been developed from the Cornegliano gas depleted field, located in the Po Valley, South-East of Milan. The gas field was originally discovered in the 1950s, produced 2.4 Bsm3 of gas from 13 wells until 1997 and was converted in December 2018. This paper presents more particularly how the ramp-up operations and commercialization were combined in an optimal manner, since they have complementary objectives. By taking into account the reservoir specificities and the wells / surface facilities capabilities, wide range of commercial services were rapidly provided to the Italian gas system while the long-term UGS performance increased continuously. The capacity of Cornegliano UGS to offer rapidly both seasonal and flexible short-term services also illustrates the future role of porous assets to provide relevant services also for hydrogen storage. The first part of this paper describes the technical aspects of the first injection and withdrawal sequences, with a particular emphasis on the pressure and water management at the reservoir and well scales. An optimal ramp-up requires both injection of the appropriate volume of cushion gas for maximizing the reservoir performance and a pressurization of the reservoir to make pore space available for gas by pushing out the aquifer. All the data collected during the ramp-up were key to update regularly the reservoir model and to gain rapidly confidence in its forecasts. The second part is focused on the commercial products design, according to the technical specificities of the UGS and the expected needs of the market. Along the ramp-up, the standard seasonal product was improved continuously in terms of both working gas volume and flowrate. Interestingly, many short-term additional capacities are offered on regular basis depending on the real-time behavior of the customers and the reservoir performance. Additionally, several specific products were also designed to respond to other market needs. For short-term market needs, the 5+2 product enables to reverse the physical flow in the UGS during the withdrawal campaign and to reinject a significant volume during the week-end which can be produced during the 5 following working days on top of the seasonal product. Various forms of "parking" product are also proposed to anticipate or postpone either injection or withdrawal in order to respond to longer term needs of the market. As a conclusion, the UGS ramp-up and the commercial activities have been conducted successfully in parallel with a continuous development rate of the seasonal product (volume multiplied by 2.5 in 5 years) and increasing flexible short-term activities (+70% in addition to seasonal volume). Diversified and increasing services can be provided to the Italian gas system with a 100% reliability, which is valuable for both the current natural gas and future hydrogen markets.