Redefining geothermal fluid properties at extreme conditions to optimise future geothermal energy extraction - REFLECT

Background

The efficiency of geothermal utilisation depends heavily upon the behaviour of the fluids that transfer heat between the geosphere and the engineered components of a power plant. Chemical or physical processes such as precipitation, corrosion, or degassing occur as pressure and temperature change with serious consequences for power plant operations and project economics. Currently, there are no standard solutions for operators to deal with these challenges.

Reykjanes, Iceland
(© V.Hardardottir)
Krafla, Iceland
(© V.Hardardottir)
Tuzla, Turkey
(© A. Baba)
Fábiánsebestyén, Hungary
(© Z.Istfan)

The aim of REFLECT is to avoid the problems related to fluid chemistry rather than treat them. This requires accurate predictions and thus a thorough knowledge of the physical and chemical properties of the fluids throughout the geothermal loop. These properties are often only poorly defined, as in situ sampling as well as measurements at extreme conditions are hardly possible to date. As a consequence, large uncertainties in current model predictions prevail, which will be tackled in REFLECT by collecting new, high quality data in critical areas.

The proposed approach includes advanced fluid sampling techniques, the measurement of fluid properties at in situ conditions, and the exact determination of key parameters controlling precipitation and corrosion processes. The sampled fluids and measured fluid properties cover a large range of salinity and temperature, including those from enhanced and super-hot geothermal systems. The data obtained will be implemented in a European geothermal fluid atlas and in predictive models that both ultimately allow to adjust operational conditions and power plant layout to prevent unwanted reactions before they occur. That way, recommendations can be derived on how to best operate geothermal systems for sustainable and reliable electricity generation, advancing from an experience-based to a knowledge-based approach.

The REFELECT approach aims at preventing problems instead of treating them. Based on known operational problems and observations, REFLECT will determine the effect of relevant fluid properties and reactions in order to enhance predictive geochemical modelling and thus the energy exploitation and life-time of geothermal power plants. By moving from reacting to occurring problems, to reflecting in advance (and acting proactively), the outcomes of this project can fundamentally change the problem-solving strategies of geothermal operators.

REFLECT focuses on operational issues associated with geothermal energy production that can be solved with better knowledge of the respective fluid properties and their chemical reactions gained within REFLECT. To gain this knowledge, key fluid properties will be measured through laboratory experiments using synthetic equivalents of natural geothermal fluids, but also through measurements on actual fluids from various geothermal sites. For collecting natural hot and super-hot fluids at depth of a well, no downhole sampling technique currently exists and therefore, the development of a high temperature downhole fluid sampler is required, which represents another goal of REFLECT. The knowledge on fluid properties obtained will be used for optimising predictive modelling and for the generation of a digital Fluid Atlas depicting the different fluid types across Europe, including those properties that will likely have an impact on energy production.

The GFZ is the coordinator of the REFLECT project and contributes its expertise to the following work packages:
WP 1: Characterizing hot fluids
WP 2: Characterizing high saline fluids
WP 3: Fluid Atlas
WP 5: Coordination, WP lead: GFZ
WP 6: Dissemination and exploitation

HORIZON 2020 - Research and Innovation Framework Programme
Grant no.: 850626

Contact

Simona Regenspurg
Group Leader
Priv. Doz. Dr. Simona Regenspurg
Geoenergy
Telegrafenberg
Building A 69, Room 202
14473 Potsdam
+49 331 288-1437
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