Thomas Driesner

• Senior Researcher at ETH Zurich

The finite element method is a powerful and general numerical method used to simulate subsurface processes. In this paper, we take recent hydraulic fracturing propagation algorithms and assess their performance when used within the finite element framework. In particular, we evaluate aperture and energy-based methodologies that are capable of extra...

A new test, referred to as axially double-edge notched Brazilian disk (ANBD), is proposed to measure true mode $$\mathrm {III}$$ III fracture toughness ( $$K_{\mathrm {IIIc}}$$ K IIIc ) of rock materials. The term true denotes a shear-induced fracturing via self-planar crack extension as opposed to a twisted tension-based one commonly observed in m...

The increased interest in subsurface development (e.g., unconventional hydrocarbon, engineered geothermal systems (EGSs), waste disposal) and the associated (triggered or induced) seismicity calls for a better understanding of the hydro-seismo-mechanical coupling in fractured rock masses. Being able to bridge the knowledge gap between laboratory an...

We evaluate the accuracy of three well-known fracture growth theories to predict crack trajectories in anisotropic rocks through comparison with new experimental data. The results of 99 fracture toughness tests on the metamorphic Grimsel Granite under four different ratios of mixed-mode I/II loadings are reported. For each ratio, the influence of t...

The Cu-Au deposit of Bor (Serbia) represents a continuum of mineralization styles, from porphyry-style ore occurring in quartz-magnetite-chalcopyrite veins and chalcopyrite disseminations to high-sulfidation epithermal Cu-Au ores in pyrite-chalcopyrite and anhydrite-sulfide veins. Decisive for the great economic importance of Bor is the presence of...

In order to assess the thermo-hydraulic modelling capabilities of various geothermal simulators, a comparative test suite was created, consisting of a set of cases designed with conditions relevant to the low-enthalpy range of geothermal operations within the European HEATSTORE research project. In an effort to increase confidence in the usage of e...

The increased interest in subsurface development (e.g., unconventional hydrocarbon, deep geothermal, waste disposal) and the associated (triggered or induced) seismicity calls for a better understanding of the hydro-seismo-mechanical coupling in fractured rock masses. Being able to bridge the knowledge gap between laboratory and reservoir scales, c...

This article discusses the scale dependence of the mode $$\mathrm {I}$$ I fracture toughness of rocks measured via the semi-circular bend (SCB) test. An extensive set of experiments is conducted to scrutinise the fracture toughness variations with size for three distinct rock types with radii ranging from 25 to 300 mm. The lengths of the fracture p...

Experimental and theoretical analyses are presented that assess true mode II fracture toughness, KIIc, fracture energy, GIIc, and associated fracture process zone (FPZ) in anisotropic rocks. The term true signifies the type of mode II crack that grows in a self-planar manner as a result of shear stresses, and thus differentiates it from a generic m...

Accurate predictions of fracture growth path resulted from fluid injection in subsurface is an important topic in geoscience projects such as wastewater injection, CO2 sequestration and geothermal energy extraction. Pressurised fluid not only creates new fractures in form of hydraulic fractures, but also potentially propagates pre-existing ones. A...

Rocks in the subsurface are exposed to high amount of confinement which can potentially suppress the formation or the development of tensile-based cracks and thus, give rise to shear-based fracture growth. However, measuring the shear fracture toughness of rocks have been studied less in the literature, as providing the required confinement to forc...

In this paper, we present the results of benchmark simulations for plume spreading during CO2 geo-sequestration conducted with the newly developed Australian CO2 Geo-Sequestration Simulator (ACGSS). The simulator uses a hybrid finite element–finite volume (FEFVM) simulation framework, integrating an asynchronous local time stepping method for multi...

Natural groundwater convection in fractures is an important mechanism of mass and heat transfer in the subsurface, locally altering temperature by several tens of degrees. The thermoelastic stresses resulting from these thermal anomalies induce thermal strains, which in turn alter the transmissivity (permeability times thickness) of the fracture an...

This paper discusses the use of the double-edge notched Brazilian disk test (DNBD) for measuring true mode II fracture toughness of rocks. The term true emphasises that in this test, not only is the crack tip loading shear-based, but also the material failure is shear-induced. Conventional mode II tests typically experience dominantly tensile failu...

This paper presents a theoretical and experimental analysis of the directional variations of different measures of Mode I fracture toughness in anisotropic rocks and possibly other types of solids. We report the theoretical basis for the directional dependence of three measures of fracture toughness: the critical stress intensity factor, the critic...

Injection of cold water into fracture zones in Enhanced Geothermal Systems (EGS) induces contractive thermo-elastic strains in the host rock, locally altering the stress state of the reservoir. Building on previous studies with horizontal fractures we examined how such thermo-elastic effects act during injection and production from a doublet inters...

Volatile outgassing from hydrous magma intrusions emplaced and cooling in the Earth's upper crust is key to a number of geologic processes including volcanic eruptions and ore deposition, yet the physical interactions between production, storage and transport of a magmatic volatile phase within magmatic intrusions and their large-scale thermal evol...

This paper presents the results of 124 pure Mode I fracture toughness tests on two types of anisotropic rocks, the metamorphic Grimsel Granite and the sedimentary Mont Terri Opalinus Clay. The results show that Mode I cracks in anisotropic rocks tend to kink towards the foliation or bedding planes that are weaker in strength. The experiment data fo...

This study investigates the thermo-hydraulic implications of three geologic scenarios for characterizing the geothermal hydrology of Basse-Terre Island, Guadeloupe. Despite newly acquired magnetotelluric, petrophysical, and geologic data, flow patterns and heat sources have remained elusive. Our simulations were performed in 2D, on a cross section...

The history of reservoir stimulation to extract geothermal energy from low permeability rock (i.e. so-called petrothermal or engineered geothermal systems, EGS) highlights the difficulty of creating fluid pathways between boreholes, while keeping induced seismicity at an acceptable level. The worldwide research community sees great value in address...

Erdenet porphyry Cu-Mo deposit is situated in the Central Asian Orogenic Belt, located north of the Tethyan tectonic domain, which formed as a result of multiple oceanic subduction events and collisions (Liu et al. 2015). Arc-magmatism resulted from the closure and subduction of the Mongol-Okhotsk Ocean under the Siberian Craton during the late Per...

The conventional semi-circular bend (SCB) test of anisotropic rocks, with symmetric loading, generates a Mixed-Mode I/II crack tip loading when the crack is not aligned with one of the principal material directions. This paper presents a modified SCB test for anisotropic rocks to ensure a pure Mode I crack tip loading. It is demonstrated that the s...

Advanced reactive transport simulations of hydrothermal systems require the modelling of diverse physico-chemical phenomena, many of which have only partially been addressed in previous studies. Utilizing newly implemented capabilities of the CSMP++GEM code, we show the relevance of three phenomena: (1) At the example of alkali feldspars, we inves...

Fluid pressure within the Earth's crust is a key driver for triggering natural and human-induced seismicity. Measuring fluid pressure evolution would be highly beneficial for understanding the underlying driving mechanisms and supporting seismic hazard assessment. Here we show that seismic velocities monitored on the 20-m scale respond directly to...

It has long been recognized that quartz precipitation from circulating hydrothermal fluids may reduce porosity and permeability near intrusions. However, the magnitude of permeability changes and potential feedbacks between flow, heat transfer, and quartz precipitation/dissolution remain largely unquantified. Here, we present numerical simulations...

A series of hydrothermal experiments have been conducted to determine equilibrium D/H fractionations between brucite and water as a function of temperature (200–600 °C), pressure (2.1–800 MPa), and dissolved NaCl (0–5 molal or 0–22.6 wt%). Along with our previous study, a total of 39 data points show that pressure and dissolved NaCl both increase t...

We present three-dimensional numerical simulations of natural convection in buried, vertical en echelon faults in impermeable host rock. Despite the fractures being hydraulically disconnected, convection within each fracture alters the temperature field in the surrounding host rock, altering convection in neighboring fractures. This leads to self-o...

Natural water convection in subvertical fractures, fracture zones, or faults can perturb the temperature field around the fracture and enhance and focus vertical heat flow within. We investigate, by means of numerical simulation, the effects of convection in a deeply buried vertical fracture zone. Fracture zone transmissivity, defined as permeabili...

In this contribution, we present a review of scientific research results that address seismo-hydromechanically coupled processes relevant for the development of a sustainable heat exchanger in low-permeability crystalline rock and introduce the design of the In situ Stimulation and Circulation (ISC) experiment at the Grimsel Test Site dedicated to...

Stable isotope signatures of oxygen, hydrogen and other elements in minerals from hydrothermal veins and metasomatized host rocks are widely used to investigate fluid sources and paths. Previous theoretical studies mostly focused on analyzing stable isotope fronts developing during single-phase, isothermal fluid flow. In this study, numerical simul...

The thermodynamic properties of potassium chloride aqueous solutions are correlated using a Pitzer model. The modeling approach used in this study is similar to that applied by Archer [10] for NaCl aqueous solutions that is currently considered to be the most accurate correlation of properties of electrolytes in a wide range of temperatures, pressu...

In this contribution we present a review of scientific research results that address seismo-hydro-mechanical coupled processes relevant for the development of a sustainable heat exchanger in low permeability crystalline rock and introduce the design of the In-situ Stimulation and Circulation (ISC) experiment at the Grimsel Test Site dedicated to st...

Earthquake-triggered volcanic activity promoted by dynamic and static stresses are considered rare and difficult-to-capture geological processes. Calderas are ideal natural laboratories to investigate earthquake–volcano interactions due to their sensitivity to incoming seismic energy. The Campi Flegrei caldera, Italy, is one of the most monitored v...

Numerical simulation of subaerial, magma-driven, saline hydrothermal systems reveals that fluid phase separation near the intrusion is a first-order control on the dynamics and efficiency of heat and mass transfer. Above shallow intrusions emplaced at <2.5km depth, phase separation through boiling of saline liquid leads to accumulation of low-mobil...

Numerical modeling is a powerful tool to investigate the response of high-enthalpy geothermal systems to production, yet few studies have examined the long-term evolution and thermal structure of these systems. Here we report a series of numerical simulations of fluid flow and heat transfer around magmatic intrusions which reveal key features of th...

Meteoric water convection has long been recognized as an efficient means to cool magmatic intrusions in the Earth's upper crust. This interplay between magmatic and hydrothermal activity thus exerts a primary control on the structure and evolution of volcanic, geothermal and ore-forming systems. Incursion of meteoric water into magmatic–hydrotherma...

Diamonds in alluvial deposits in Southeast Asia are not accompanied by indicator minerals suggesting primary kimberlite or lamproite sources. The Meratus Mountains in Southeast Borneo (Province Kalimantan Selatan, Indonesia) provide the largest known deposit of these so-called “headless” diamond deposits. Proposals for the origin of Kalimantan diam...

Various thermodynamic properties of H2O that are defined as pressure or temperature derivatives of some other variable, such as isothermal compressibility (β, pressure derivative of density), isobaric thermal expansion (α, temperature derivative of density), and specific isobaric heat capacity (cf, temperature derivative of enthalpy), all show larg...

Reactive transport simulation on unstructured meshes can provide fundamental insight into the effect that geometric complexity of geologic structures has on fluid flow and development of reaction fronts. When applied to conditions ranging from ambient to hydrothermal and combined with compressible flow, accounting for geometric complexity provides...

Magmatic-hydrothermal systems associated with upper crustal plutons strongly influence volcanic and geothermal processes and form important mineral deposits. Fluids released from plutons are commonly saline and undergo phase separation into high-salinity brines and lowsalinity vapors upon ascent. While brine-vapor immiscibility has been extensively...

A new and economically attractive type of geothermal resource was recently discovered in the Krafla volcanic system, Iceland, consisting of supercritical water at 450 °C immediately above a 2-km deep magma body. Although utilizing such supercritical resources could multiply power production from geothermal wells, the abundance, location and size of...

The densities of aqueous solutions in the systems Na2SO4-H2O and Na2SO4-NaCl-H2O were determined experimentally at temperatures from (298.15 to 523.15) K and pressures up to 70 MPa, and over a wide range of salt concentrations (up to 5 mol·kg-1 of NaCl and up to 1.2 mol·kg-1 of Na2SO4). The measurements were conducted in vibrating-tube densimeters...

To optimize the behaviour of an ATES (aquifer thermal energy storage), to estimate its efficiency and to identify the optimal well locations, the planned installation was simulated with a FE-FV (finite element-finite volume) simulator with realistic water properties, created on the basis of the CSMP++ (Complex Systems Modelling Platform) software l...

Subduction-related magmas have higher volatile contents than mid-ocean ridge basalts, which affects the dynamics of associated submarine hydrothermal systems. Interaction of saline magmatic fluids with convecting seawater may enhance ore metal deposition near the seafloor, making active submarine arcs a preferred modern analogue for understanding a...

The densities of aqueous solutions in the systems CaCl 2 −NaCl−H 2 O and MgCl 2 −NaCl−H 2 O were determined exper-imentally at temperatures from (298.15 to 523.15) K, pressures up to 70 MPa and over a range of composition at ionic strengths from (0.1 to 18) mol·kg −1 . The vibrating-tube densimeters used for the experi-mental measurements have an a...

The magmatic to hydrothermal transition in the Late Cretaceous Elatsite porphyry Cu-Au-(Mo-platinum group element) deposit has been studied in a suite of samples with clear timing relations between porphyry dikes, magmatic-hydrothermal veins, silicate melt inclusions in quartz veins, fluid inclusion generations, and ore minerals. Ore mineralization...

GEMSFIT, a parallelized open-source tool for fitting thermodynamic activity models has been developed. It is the first open-source implementation of a generic geochemical thermodynamic fitting tool coupled to a chemical equilibrium solver which uses the direct Gibbs energy minimization approach. This enables speciation-based fitting of complex solu...

The densities of KCl−NaCl aqueous mixtures were determined at temperatures from (298.15 to 523.15) K, pressures up to 40 MPa, and over a range of compositions at ionic strengths from (0.1 to 5.8) mol·kg −1 . A vibrating-tube densimeter used for the experimental measurements provides the accuracy on density better than 2·10 −4 g·cm −3 . The mean app...

Maureen is the largest among several U (-Mo-F) prospects occurring along a Late Devonian unconformity in the Georgetown area, northern Queensland, Australia. Mineralization is structurally controlled by the intersection of steep east-west fractures with an unconformity between a Proterozoic basement and a Paleozoic cover sequence of continental sed...

Thermohaline convection of subsurface fluids strongly influences heat and mass fluxes within the Earth's crust. The most effective hydrothermal systems develop in the vicinity of magmatic activity and can be important for geothermal energy production and ore formation. As most parts of these systems are inaccessible to direct observations, numerica...

The densities of aqueous solutions in the systems CaCl2-NaCl-H2O and MgCl2-NaCl-H2O were determined experimentally at temperatures from (298.15 to 523.15) K, pressures up to 70 MPa and over a range of composition at ionic strengths from (0.1 to 18) mol·kg-1. The vibrating-tube densimeters used for the experimental measurements have an accuracy on d...

This study applies the fluid flow and heat transport code CSMP++ to simulate the cooling of intrusions and the sub-surface structure and evolution of hydrothermal systems. These 2D simulations are focused on characterizing the influence of important factors such as magma chamber depth as well as system-scale permeability. Preliminary results show t...

NaCl is the most common solute in aqueous fluids in many geological settings but the thermodynamic properties of binary NaCl–H 2 O solutions have remained understudied at pressures above 0.5 GPa. We report the first high-pressure (>0.5 GPa) density data for NaCl–H 2 O fluids derived from acoustic velocity measurements in 1m and 3m NaCl solutions in...

This volume presents an extended review of the topics conveyed in a short course on Geothermal Fluid Thermodynamics held prior to the 23rd Annual V.M. Goldschmidt Conference in Florence, Italy (August 24–25, 2013). Geothermal fluids in the broadest sense span large variations in composition and cover wide ranges of temperature and pressure. Their...

Chemical interactions between fluids and minerals play a central role in numerous geological processes. In a hydrothermal environment, such reactions are usually referred to as fluid-rock interaction or water-rock interaction and lead to alteration of rocks by changing the mineral assemblages and compositions. During fluid-rock interaction the flui...

The origin of crustal-scale silicic magmatism remains a matter of debate, and notable uncertainty exists concerning the physical mechanisms that drive ascent and emplacement of felsic magmas in upper crustal regions. A 2-D numerical model demonstrates that injection of mantle-derived mafic magma into a partially molten hot zone in the lower crust c...

The formation of porphyry copper deposits requires a focused flux of magmatic fluid, expelled from a large reservoir of water-, metal-, and sulfur-rich magma. The dimensions of this usually hidden magma reservoir are difficult to determine but can be constrained by combining geophysical observations with thermal constraints and the mass balance imp...

The late Alpine evolution of the Rhodope Massif in southern Bulgaria and northern Greece involved postcollisional extension, which generated detachment faults, syndeformational sedimentary basins, and exhumation of a large metamorphic core complex composed of gneisses and marbles: the Central Rhodopian dome. Closely associated with this complex, su...

Unconventional geothermal resources at supercritical conditions have been inferred to occur beneath high-enthalpy systems in active magmatic environments, and bear the potential to increase electricity production from a geothermal well by an order of magnitude. The high specific enthalpies of these fluids cannot be explained by simple convection mo...

The thermodynamic properties of a 1 m Na(2)SO(4) solution have been determined to 773 K and 3 GPa from acoustic velocity measurements in externally heated diamond anvil cell using Brillouin spectroscopy. The measured acoustic velocities were inverted to obtain the density of the aqueous electrolyte solution with an accuracy of 0.3%-0.5%, and an equ...

Numerical, multiphase pure-water simulations were performed to study the first-order geologic and physical parameters controlling the style and distribution of hydrothermal venting at Brothers volcano, southern Kermadec arc, New Zealand. By comparing the results for different permeability scenarios, we can show that the location of venting on the i...

Earning a High Grade Most of the world's copper and molybdenum come from porphyry-type ore deposits in Earth's crust. The metals are deposited either as veins of concentrated metals in fractured rock or in a confined shell, associated with the edges of magma chamber plumes. But it remains unclear why a front of sharp temperature-pressure gradients,...

Geochemical modeling of fluid-rock interaction in geothermal environments is a demanding task because of the prevalent high temperatures, pressures and salinities. Solution speciation, mineral compositions and assemblages as well as gas compositions are typically computed from multicomponent-multiphase thermodynamic models for standard state proper...

Numerical simulations of fluid flow in magmatic hydrothermal systems require the coverage of fluid properties over wide ranges of pressure, temperature and salinity. To this end, an equation of state for H2O-NaCl and its numerical application has been developed (Driesner & Heinrich, 2007; Driesner, this volume). As saltwater fluids are multi-phase,...

The system H2O-NaCl is the simplest proxy to saline fluids in the earth's crust. Such fluids play a central role in processes ranging from basinal fluid flow through hydrothermal heat transport along mid-ocean ridges to ore formation in magmatic-hydrothemal systems. Addition of NaCl strongly modifies the phase diagram of water (Driesner & Heinrich,...

We apply a new, C++-based computational model for hydrothermal fluid-rock interaction and scale formation in geothermal reservoirs. The model couples the Complex System Modelling Platform (CSMP++) code for fluid flow in porous and fractured media (Matthai et al., 2007) with the Gibbs energy minimization numerical kernel GEMS3K of the GEM-Selektor (...

High temperature, pressure, and fluid salinities render geochemical modeling of fluid-rock interactions in Enhanced Geothermal Systems a demanding task. Accurate prediction of fluid-mineral equilibria strongly depends on the availability of thermodynamic data and activity models. Typically, the Pitzer activity model is applied for geothermal fluids...

The International Partnership for Geothermal Technology (IPGT) provides a forum for geothermal leaders from government, industry, and academia to coordinate their efforts and collaborate on projects. The IPGT has defined a number of areas of technology focus, establishing working groups to summarize the current stateof-the-art and provide recommend...

Brothers volcano is part of the southern Kermadec intra-oceanic arc located northeast of New Zealand, and is one of the world's best-studied active submarine volcanoes. It provides insight into the complex subseafloor hydrology of a submarine arc volcano with evidence for different stages in its magmatic-hydrothermal evolution [1]. The volcanic edi...

The fluids released from subducted slabs are mainly composed of H2O, CO2 and different cations and play a key role in many geological processes in the Earth's crust and mantle. Although carbonate minerals are stable along typical subduction isotherms [Biellmann et al., 1993; Isshiki et al., 2004], the occurrence of CO2 in fluids inclusions (Roedder...

We present a novel computational tool for modelling temporally and spatially varying chemical interactions between hydrothermal fluids and rocks that may affect the long-term performance of geothermal reservoirs. The code is written in C++. It incorporates fluid-rock interaction and scale formation self-consistently, via a modular coupling approach...

A consortium of research groups from ETH Zurich, EPF Lausanne, the Paul Scherrer Institut and the University of Bonn collaborates in a comprehensive program of basic research on key aspects of the Enhanced Geothermal Systems (EGSs). As part of this GEOTHERM project (www.geotherm.ethz.ch), we concentrate on the fundamental investigation of thermodyn...

The dynamic behavior of magmatic hydrothermal systems entails coupled and nonlinear multiphase flow, heat and solute transport, and deformation in highly heterogeneous media. Thus, quantitative analysis of these systems depends mainly on numerical solution of coupled partial differential equations and complementary equations of state (EOS). The pas...

Geofluids (2010) 10 , 132–141 Abstract While the fundamental influence of fluid properties on venting temperatures in mid‐ocean ridge (MOR) hydrothermal systems is now well established, the potential interplay of fluid properties with permeability in controlling heat transfer, venting temperatures, and venting salinities has so far received little...

Active high-temperature vents at the seafloor greatly contribute to the heat transport system at the Earth's surface and significantly influence the chemistry of crust and overlying ocean. While mid-ocean ridge systems have been intensely studied in the last decades, hydrothermal activity along convergent plate boundaries has received deeper attent...

1] High-resolution numerical simulations give clear insights into the three-dimensional structure of thermal convection associated with black-smoker hydrothermal systems. We present a series of simulations that show that, at heat fluxes expected at mid-ocean ridge spreading axes, upflow is focused in circular, pipe-like regions, with the bulk of th...