Modeling enhanced geothermal systems and the essential nature of large-scale changes in permeability at the onset of slip

作者：Miller S A^*

来源：Geofluids, 2015, 15(1-2): 338-349.

DOI：10.1111/gfl.12108

• crustal permeability
• permeability of enhanced geothermal systems
• transient permeability

The permeability structure resulting from high fluid pressure stimulation of a geothermal resource is the most important parameter controlling the feasibility and the viability of enhanced geothermal systems (EGS), yet is the most elusive to constrain. Linear diffusion models do a reasonably good job of constraining the front of the stimulated region because of the t(1/2) dependence of the perturbation length, but triggering pressures resulting from such models, and the permeability inferred using the diffusivity parameter, drastically underestimate both permeability and pressure changes. This leads to incorrect interpretations about the nature of the system, including the degree of fluid pressures needed to induce seismicity required to enhance the system. Here, I use a minimalist approach to modeling and show that all of the observations from Basel (Switzerland) fluid injection experiment are well matched by a simple model where the dominant control on the system is a large-scale change in permeability at the onset of slip. The excellent agreement between observations and these simplest of models indicates that these systems may be less complicated than envisaged, thus offering strategies for more sophisticated future modeling to help constrain and exploit these systems.

• 出版日期2015-2