Periodic Reporting for period 1 - NERUDA (Numerical and ERT stUdies for Diffusive and Advective high-enthalpy systems)
Periodo di rendicontazione: 2018-11-01 al 2020-10-31
The increasing interest in hydrothermal systems derives from the required development of renewable energies. Low-enthalpy shallow hydrothermal energy represents an attractive source of heat. For this reason, the number of installations has been continuously rising for the past 15 years. High-enthalpy environments are still underexploited as drilling in deep and hot reservoirs is technologically challenging. Nevertheless, the economic returns of these systems are such that their exploitation will probably develop in the next years. High-enthalpy, convection dominated hydrothermal systems preferentially develop at active plate margins where active tectonics and volcanism are commonly found. In such environment faults have a major control on fluid flow. The behaviour of these faults is however difficult to predict due to their spatially variable structure and permeability. The role of faults on the flow is strongly controlled by their hydraulic properties with respect to those of the host rocks. If faults have lower permeability than the host rocks, they act as barrier to the flow and can seal reservoirs. Vice versa, when host rocks have a lower permeability, faults can act as conduits focusing fluid flow. Assessing the permeability of fault zones is challenging due to the lack of in situ measurements and require thus complementary methods. In the last decade, electrical resistivity tomography (ERT), combined with other fluid data (e.g. temperature and CO2 concentration), has been employed to identify and image the geometry of shallow hydrothermal systems. This method relies on the measurement of the subsurface electrical resistivity and allows the identification of regions where fluids are focused. Complementary numerical simulations of fluid flow are required to constrain the petrophysical properties of the host rocks. Over the past decades, several powerful numerical codes have been developed for the simulation and quantification of fluid flow in the upper crust. However, most of these codes either have a complex structure or lack some flexibility for meshing and the characterization of fluid properties. A new user-friendly and more accessible (e.g. MATLAB based) code is required for both industry and academic purpose.
The goal of NERUDA is to deepen our understanding of high-enthalpy hydrothermal systems by combining numerical simulations of fluid flow with temperature, soil CO2 and deep geoelectrical measurements. The main scientific objective of NERUDA is the development of a geothermal module in the MATLAB Reservoir Simulation Toolbox (MRST), an open-access software for the simulation of fluid flow in reservoirs developed by SINTEF, Oslo, Norway. This module is expected to have a large impact on the scientific community both in academia and in the industry for the simulation of geothermal problems. The second important scientific contribution is to document the tectonic control of a the Tolhuaca hydrothermal system combining geophysical data with temperature, CO2 flux measurements and structural data to propose an evolution model for the hydrothermal system. The collected data will bring further constrains for the exploration of the area that is investigated for geothermal activities by a local company. Generally, NERUDA will deepen our understanding of the tectonic control of high-enthalpy hydrothermal systems, which is also relevant for the exploitation of geothermal energy in Europe.
The goal of NERUDA is to deepen our understanding of high-enthalpy hydrothermal systems by combining numerical simulations of fluid flow with temperature, soil CO2 and deep geoelectrical measurements. The main scientific objective of NERUDA is the development of a geothermal module in the MATLAB Reservoir Simulation Toolbox (MRST), an open-access software for the simulation of fluid flow in reservoirs developed by SINTEF, Oslo, Norway. This module is expected to have a large impact on the scientific community both in academia and in the industry for the simulation of geothermal problems. The second important scientific contribution is to document the tectonic control of a the Tolhuaca hydrothermal system combining geophysical data with temperature, CO2 flux measurements and structural data to propose an evolution model for the hydrothermal system. The collected data will bring further constrains for the exploration of the area that is investigated for geothermal activities by a local company. Generally, NERUDA will deepen our understanding of the tectonic control of high-enthalpy hydrothermal systems, which is also relevant for the exploitation of geothermal energy in Europe.
In December 2018, we conducted a first field work in Chile in the areas of both Cordon Caulle and Tolhuaca hydrothermal systems to investigate the possibility of realising an ERT acquisition and to estimate the associated logistics. Following uncertainties in the logistics, we conducted in February – March a second light field campaign at the Tolhuaca hydrothermal system, in Chile. During the field campaign at the Tolhuaca hydrothermal systems we measured the soil CO2 degassing using an accumulation chamber and documented the soil temperature with a thermocouple. We also measured the temperature of the hydrothermal manifestations, mapped the main geological units and sampled some rocks. The temperature and CO2 data were processed with statistical and geostatistical methods using the MATLAB and GSLIB software. A geological map of the investigated area was produced using the ArcGIS software. The researcher, Marine Collignon, initiated and developed a collaboration with Transmark Chile SpA, which is a geothermal company holding a licence for geothermal exploration and exploitation in the Araucania region around Tolhuaca Volcano. In the framework of this collaboration, we obtained data previously collected in the context of geothermal exploration that have been used for the interpretation of our own data and to build a conceptual model of fluid flow for the Tolhuaca hydrothermal systems. These results have been submitted for publication to Journal of Volcanology and Geothermal Research.
In parallel to the field work activities and subsequent processing of the data, the researcher developed a geothermal module in MRST, whose functioning and well tested parts have been made freely and openly available for the first time in December 2019 as part of the MRST 2019b release. This part of the module is now frequently released by SINTEF under a GNU GPL, while the researcher keeps on the update and development of the geothermal module, jointly with researchers from SINTEF. A dedicated book chapter has been written by Marine Collignon and SINTEF collaborators explaining in details the main functions and provided examples inside the geothermal module. This chapter is part of a book entitled Advanced Modelling with the MATLAB Reservoir Simulation Toolbox, edited by SINTEF and published by Cambridge that should be released by the end of the year. The module has also been used to investigate the geothermal potential of the Great Geneva Basin in the framework of a project led by the supervisor, Matteo Lupi, and resulted so far into two publications.
In parallel to the field work activities and subsequent processing of the data, the researcher developed a geothermal module in MRST, whose functioning and well tested parts have been made freely and openly available for the first time in December 2019 as part of the MRST 2019b release. This part of the module is now frequently released by SINTEF under a GNU GPL, while the researcher keeps on the update and development of the geothermal module, jointly with researchers from SINTEF. A dedicated book chapter has been written by Marine Collignon and SINTEF collaborators explaining in details the main functions and provided examples inside the geothermal module. This chapter is part of a book entitled Advanced Modelling with the MATLAB Reservoir Simulation Toolbox, edited by SINTEF and published by Cambridge that should be released by the end of the year. The module has also been used to investigate the geothermal potential of the Great Geneva Basin in the framework of a project led by the supervisor, Matteo Lupi, and resulted so far into two publications.
The main impact of NERUDA is the release of an open-access numerical tool to simulate geothermal problems. This tool has been used for two geothermal studies in the Great Geneva Basin and for three internal projects at SINTEF. The viability of a geothermal energy system, either for production or storage, depends on its economic gain (i.e. energy efficiency or storage capacity versus operational and drilling costs) and compliance with legal regulations. Evaluating this viability requires a solid knowledge of the groundwater flow characteristics and reservoir properties, which can only be achieved through numerical simulations. The open-access, free of charge geothermal module developed in NERUDA is thus expected to have a considerable impact for industrial applications that would benefits for society and helps moderating the effects of climate change by the development of renewable energies. The module is expected to be used, as the other modules of MRST, by both academic researchers and private companies.