Guided Geothermal Exploration in Hot Sedimentary Aquifers
Abstract
The search for a suitable reservoir site in a geothermal system depends on many factors. In Hot Sedimenatry Aquifer systems (i.e. deep, permeable geological units filled with hot fluids and with a significant regional extent), mostly important are hydraulic conductivity, fluid temperature and heat capacity. These factors are strongly coupled. For example, hydraulic conductivity depends on fluid viscosity which itself is a function of temperature. We can therefore derive the most meaningful estimation of parameters at depth when we consider all these coupling effects - instead of simply interpolating measured values. The best way to incorporate the relevant factors and their couplings is to create a mathematical model of the subsurface, considering all important physical effects (usually done in thermo-hydraulic simulations).
Results of these simulations are the distribution of thermodynamic properties (temperature, pressure) and rock properties (permeability, porosity, thermal conductivity, etc.) in space. Only certain combinations of these properties will finally lead to a suitable location for a geothermal reservoir. Also, other relevant aspects have to be considered, like the regional extent of the aquifer, its thickness and natural groundwater flow. We developed methods to combine many of these relevant factors into coherent models, the results of which can be visualized in simple exploration maps. We are considering two highly important factors: (a) the available heat density, related to a minimum temperature (``Lindal-Maps'') and (b) the sustainability of the system, considering a potential pumping and reinjection well doublet scheme. Example applications show how our estimations can help locate a potential geothermal reservoir. Estimation of a maximal pumping rate for the theoretical case of no thermal breakthrough, in the presence of advection. This is of practical significance as areas with a high value can also be expected to allow a higher sustainable pumping rate.- Publication:
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AGU Fall Meeting Abstracts
- Pub Date:
- December 2010
- Bibcode:
- 2010AGUFM.H33D1170W
- Keywords:
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- 0530 COMPUTATIONAL GEOPHYSICS / Data presentation and visualization;
- 1847 HYDROLOGY / Modeling;
- 3225 MATHEMATICAL GEOPHYSICS / Numerical approximations and analysis