Decarbonisation of the energy sector not only relies on subsurface CO2 storage, but also on maximisation of the use of unconventional and renewable energy resources, such as geothermal energy and energy storage. However, many uncertainties exist regarding aspects such as the efficiency and potential of these resources and associated risks like induced seismicity. With this session, we aim to provide an overview of such aspects, highlighting recent advances in our understanding. We welcome contributions describing lab, field and modelling studies relevant for all aspects of geo-energy, including CO2 storage.

Furthermore, this session focuses on modelling of processes associated with geological subsurface utilization, where we have in mind applications related to chemical or thermal energy storage, hydrocarbon production and storage, storage of carbon dioxide etc, all in the context of ensuring a safe and sustainable energy supply.
Such utilization of the geological subsurface, usually related with fluid flow due to injection or production, may induce changes in the recent hydraulic, thermal, mechanical and chemical regimes. Our session aims at the integration of experimental and numerical modelling methods for quantification and prediction of the potential impacts resulting from geological subsurface utilization including:

• Site characterization and determination of site-specific geological and process data.

• Development of static geological models.

• Integration of experimental data into static and dynamic models as well as application of numerical models for experimental design and interpretation.

• Development and benchmarking of modelling tools.

• Model and parameter upscaling techniques.

• Model coupling addressing the interaction of thermal, multi-phase flow, geochemical and geomechanical processes in the fluid-rock system.

• Application of modelling tools for site characterization and prediction of potential impacts.

• Methods for risk assessment and efficient site operation.

Thermal, hydraulic, mechanical and chemical (THMC) processes in geological settings are of increasing interest in different geo-scientific fields. This is especially the case within current research applied to exploration and usage of natural and mineral resources from the underground. This session is intended as a scientific platform to present and discuss studies focused on various kinds of processes relevant for geo-energy related applications. These comprise, but are not limited to, enhanced oil recovery, aquifer storage, and hydro- and enhanced geothermal applications. Therefore, we invite contributions ranging from innovative laboratory experiments, analytical solutions and mathematical model applications to the discussion of an improved way to understand the history, current state as well as future performance of reservoirs.
More specifically, we welcome contributions dealing with analysis and quantification of: (i) fluid flow, permeability, fluid conductivity; (ii) electrical properties, conductivity, resistivity and permittivity in both real and complex domains; (iii) heat flow, geothermal states, thermal conductivity and diffusivity; (iv) transport of energy by elastic waves, their velocities and the dispersion of compression, shear and other types of elastic waves; and (v) mechanical properties of fractured and intact rock materials. Contributions on coupling mechanisms of THMC-processes in fractured and intact reservoir rocks are of special interest.
This session is intended to provide an overview of current research activities in this field. By discussing advances and challenges in quantifying coupled physical processes in geological settings and their implications it aims to stimulate new ideas for future work.

The presence of fractures, whether natural or induced, has become increasingly important in recent years in the exploitation of Earth’s natural resources. Especially in rocks that have a low matrix permeability, the presence of fractures is critical for reaching flow rates sufficient for economic hydrocarbon production and heat extraction for geothermal reservoirs. Better prediction of subsurface fracture arrangements and their mechanical and flow response have become an increasingly relevant field of research.
We propose here a multi-disciplinary session on the arrangement and mechanical evolution of natural and induced fracture networks and their response to fluid flow in low-permeability rocks on a multitude of scales (from pore-scale to basin-scale). We encourage submissions from experimental, numerical and field studies on fracture network formation and control on fluid flow of naturally and hydraulically fractured systems. Also studies that address the role of fractures on both shale gas and tight geothermal reservoir application cases are welcomed. We especially encourage early-career scientists to present their work in this session.

Numerous cases of induced/triggered seismicity have been reported in the last decades as a result of the increasing interest in fluid injection/extraction projects related to geo-resources exploration. When such seismicity is felt by the population, it can negatively affect public perception of geo-energies and may lead to the cancellation of important projects. Furthermore, large earthquakes may jeopardize wellbore stability and damage surface infrastructure. Thus, a key issue is to better understand how to monitor and model the processes leading to seismicity, in order to facilitate the development of effective and reliable forecasting methodologies during deep underground exploitation.
Given the complexity of induced seismicity processes and their interdisciplinary nature, understanding the triggering mechanisms implies to take into account coupled thermo-hydro-mechanical-chemical processes.
In this session, we invite contributions from research aimed at understanding such processes during exploitation of deep underground resources, including hydrocarbon
extraction, wastewater disposal, geothermal
energy exploitation, hydraulic fracturing, gas storage and production, mining, and reservoir impoundment for hydro-energy.
We particularly encourage novel contributions based on laboratory and underground near-fault experiments, numerical modelling, spatio-temporal variations of physical parameters and seismicity, and fieldwork, covering both theoretical and experimental aspects of induced and triggered seismicity at multiple spatial and temporal scales.

Hydraulic stimulation is a well-operation that aims at enhancing fluid flow at depth. It is applied to exploit unconventional hydrocarbon reservoirs with low permeability and deep geothermal resources. Induced earthquakes frequently accompany the injection of fluids into boreholes potentially leading to damage to infrastructure at the surface and thus generally raising public concern. Damage caused by such events have already terminated Enhanced Geothermal Energy projects in South Korea and Switzerland. Hence, finding safe stimulation methods is critical for future use and public acceptance of geothermal energy projects and potential other forms of energy extraction from the underground. A range of stimulation techniques have been developed to increase the permeability of low-permeable reservoirs, however, our understanding of the processes involved in the formation of hydrofracs and hydroshears and the effectiveness of these operations regarding flow enhancement are still rather limited. A series of successful mine-back experiments have been performed in a range of underground laboratories in Europe. For this session, we invite presentations covering the full range of rock mechanics experiments, underground laboratory testing, and field-scale operations aiming at improving the fundamental understanding of stimulation operations.

Induced and triggered seismicity are common phenomena associated with sub-surface exploration and remote seismic events, respectively, and have been related to hydrocarbon extraction, hydraulic fracturing, geothermal exploitation, open-pit crater formation and underground mining operations, CO2 sequestration, and filling of new water reservoirs. Public awareness and concern of induced seismicity has become ubiquitous in locations where subsurface exploration and storage is carried out in close proximity to communities. Of particular concerns are massive fluid injections for hydro-fracturing to increase subsurface permeability as well as long-term injection in disposal wells. These concerns have led to regulations to passively monitor induced seismicity and consequently to a wealth of continuous seismic data. In contrast to the increase in data volume, our understanding of the relationship between exploitation techniques and induced seismicity as well as earthquake-earthquake interactions is still limited. New processing methods to analyze data and quantitative models to improve our understanding of the causal relationship between exploitation and seismicity have been developped. The current session is intended to provide a platform to present the latest research, field studies, theoretical and modelling aspects as well as methods for seismic hazard analysis related to induced and triggered seismicity. Topics to be presented include spatio-temporal variations of physical parameters in reservoirs and natural environments including stress and pressure changes, spatial-temporal patterns of seismicity, source mechanisms of micro- or larger-scale seismicity, mechanisms for induced events and seismic interaction, as well as, fracture-induced anisotropy. Contributions are sought from fundamental and applied research covering the fields of oil and gas operations including hydro-fracturing, geothermal exploitation particularly related to enhanced geothermal systems, open pit and underground mining, CO2 storage, and other fields such as volcano-seismology where induced and triggered seismic activity is observed.

Geofluids (i.e. fluids located in the subsurface) are increasingly becoming of interest due to their significant role as natural resources. These fluids span a vast range of geological environments including groundwater drinking resources, shale gas and oil, deep/shallow geothermal resources and hydrothermal mineral resources. Despite being valuable resources, geofluids are both vulnerable to contamination or may themselves represent a potential source of contamination through externally-driven mechanisms, as in the case of shale gas extraction, CO2 leaking or land use for agriculture purposes. Ont he other hand geofluids themselves can be a source of natural contamination as in the geogenic contamination of groundwater resources containing elevated levels of trace elements including arsenic (As), chromium (Cr), iron (Fe), and uranium (U), amongst others. Strategic management of geofluids and protection of geological resources related to them is indispensable for the future sustainable development of these societal and economically important resources. The characterization of geofluids and their behaviour in natural or artificial (human-driven) circumstances requires a deep understanding of complex physical, geochemical and microbiological processes. They are influenced directly by geological setting, structural evolution, and fluid flow systems.

The aim of this session is to foster scientific discussion between those with interest in a range of geofluid systems to better understand the role which these fluids have as socio-environmental and economic resources. The session emphasises the importance of lithological & mineralogical characterizationof various systems including in aquifers for a range of geogenic contaminants in groundwater, specifically addressing the source pathways and mobilisation mechanisms. The session also welcomes work including fluid flow, hydrology, geochemistry, environmental tracers, microbial investigations and both numerical and statistical modelling in support of fluid and resource management.

The session is supported by the RGFC-IAH (‘Regional Groundwater Flow Commission’ of International Association of Hydrogeologists) and the EU H2020 ENeRAG (‘Excellency Network Building for Comprehensive Research and Assessment of Geofluids’) project.