Application of hydrogeological parameters for evaluating theudthermal resource potential of deep groundwater systems.

摘要

Geothermal energy has significant global potential as a clean non-intermittent energy resource.udExploiting geothermal energy uses water which either flows naturally or is stimulated to flow inudthe sub-surface within deep aquifers or fractured basement. Therefore, it is necessary to understandudfluid flow in the upper crust of the Earth (0–5 km depth). Fluid flow could be through waterbearingudporous and permeable media (e.g. sandstones and limestones), fractured dry rocks or fluidudfilled fault zones. The UK has low to medium temperature geothermal resources related to pastudintrusive igneous activity. A thorough understanding of these low to medium temperature systems isudparticularly important, because their usefulness will only be realised by optimising site conditionsudfrom a geological and engineering standpoint. It is necessary not only to examine the temperaturesudat depth but to ensure that fluid flow is sufficient so that the geothermal resource is not quicklyuddepleted. Conversely, we also need to ensure that any fluids removed for heat extraction can beudre-injected elsewhere in the system to prevent discharge of warm, chemically unsuitable fluids toudsurface water courses. The requirement to understand these systems is critical for the UK becauseudeconomic exploitation of a marginally productive resource relies upon the interplay of severaludfinely balanced factors. This paper presents a hydrogeological evaluation of two geothermal caseudstudies, one from north-east England and one from the North Sea. The applicability of these twoudcase studies to other marginally productive geothermal areas is then discussed.