Seasonal Deep Aquifer Thermal Energy Storage in the Gassum Sandstone Formation
H.D.H. Holmslykke, C. Kjøller and I.L. Fabricius
Event name: Fourth Sustainable Earth Sciences Conference
Session: Energy Storage - Evaluating Novel Concepts
Publication date: 03 September 2017
Info: Extended abstract, PDF ( 780.29Kb )
Price: € 20
Seasonal storage of excess heat in hot deep aquifers is considered to optimise the usage of commonly available energy sources. The potential chemical reactions caused by heating the Gassum Sandstone Formation to up to 150°C is investigated by core flooding experiments combined with petrographic analysis and geochemical modelling. Synthetic formation water is injected into two sets of Gassum Formation samples at 25°C, 50°C (reservoir temperature), 100°C and 150°C with a velocity of 0.05 PV/hr and 0.1 PV/hr, respectively. A significant increase in the aqueous concentration of silicium and iron with increasing temperature is observed due to dissolution of silica and siderite. Increasing the reservoir temperature from 50°C to 100°C enhanced the naturally occurring weathering of Na-rich feldspar to kaolinite. Dissolution of quartz increased sharply above 100°C and was the dominating process at 150°C. At temperatures ≤100°C, the silicium concentration was controlled by a dynamic equilibrium between feldspar dissolution and kaolinite precipitation while the concentration was kinetically controlled by quartz dissolution at 150°C. The results imply that storage of excess heat in the Gassum Formation in the Stenlille area may be possible provided operational precautions are taken.