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Hydrofracture propagation and arrest in active geological settings: understanding high temperature / high pressure coupled processes through new laboratory rock-physics simulations

English title Hydrofracture propagation and arrest in active geological settings: understanding high temperature / high pressure coupled processes through new laboratory rock-physics simulations
Applicant Burg Jean-Pierre
Number 137867
Funding scheme Project funding
Research institution Geologisches Institut ETH Zürich
Institution of higher education ETH Zurich - ETHZ
Main discipline Geology
Start/End 01.12.2011 - 30.11.2015
Approved amount 299'016.00
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All Disciplines (3)

Discipline
Geology
Geophysics
Other disciplines of Earth Sciences

Keywords (1)

Hydrofracture

Lay Summary (English)

Lead
ETH Zurich Rock Deformation Laboratory
Lay summary

The Earth currently hosts some 600 volcanoes which are known to have erupted in historical time, with nearly 500 million people living on the edifice or nearby. Of these, 40 volcanoes are located in Europe alone, where two or three are normally in eruption each year. Some 4-5 million people live within sight of an active European volcano, while at least 10% of the EU population is economically vulnerable to an eruption. Seismicity and ground deformation are the short-term precursory phenomena most frequently detected before a volcanic eruption, occurring as the Earth's crust is distorted by magma pushing its way to the surface, and as fluids (magma, volcanic gas and/or hydrothermal fluids) move within faulted rock. One of the key processes occurring these events is known as hydrofracture – the act of deforming and fracturing a rock or other competent body by the use of fluid pressure. Hydrofracturing occurs naturally, such as in volcanically active areas where molten magma is the pressurising fluid, giving rise to geological features known as dykes that are emplaced into the surrounding rock; and also artificially, for example in geological engineering applications such as creating geothermal reservoirs and enhancing gas production (known as ‘fracking’). However, our knowledge of natural hydrofracture processes, especially those relating to high-pressure, high-temperature processes is very limited, partly because of the complex feedbacks, or coupling, that occurs between the thermal, hydraulic, and mechanical aspects of the process. Such investigations are of broad significance to the geological community from both the pure research (e.g. ore body emplacement, hydrothermal circulation) as well as the applied geosciences (e.g. geothermal energy extraction and enhanced hydrocarbon recovery). However, previous work was either (a), limited to high temperatures under simple confined samples that are not truly representative of the scenario in the shallow crust, or (b), to modest confinement at room temperature.

 

To investigate, this project will simulate the processes in a laboratory environment, recreating conditions at approximately 4 km depth in the volcano-tectonic system (temperatures of ~1000 °C, and pressures of ~200 MPa) using unique ‘nested’ samples comprising a molten conduit axial core fed by a reservoir. Research will be three-fold. Firstly the project will explore the dependence and fracture mechanics behaviour of the outer material (shell) of country rock upon pressure and temperature and with respect to measured seismicity and material properties. Secondly, the project will simulate magma propagation through the composite samples that use a range of alternative soft/hard rock layers to investigate under what conditions of pressure / temperature and rocks fracture property ratio that magma is observed to arrest, or deflect upon encountering such stress ‘barriers’. Finally, fieldwork will be conducted to collect samples from a selected range of volcanic environments; Seljadour Basalt (Iceland), Neopolitan Yellow Tuff (Italy), and Lipary Rhyolite (Aeolian chain, Italy). All of these laboratory data will be used as input to a previously published model for magma propagation and arrest in order to explore the key differences between uniaxial (unconfined) and triaxial (confined) scenarios. Thus, for the first time under in-situ conditions, an opportunity exists to calibrate a number of key  models, in particular the Gudmundsson (2011) hypothesis, and to asses the conditions that magma bodies intrude the overburden, with application to ore bodies, geothermal energy extraction, and volcano-tectonics.
Direct link to Lay Summary Last update: 10.01.2013

Responsible applicant and co-applicants

Employees

Name Institute

Publications

Publication
How temperature-dependent elasticity alters host rock/magmatic reservoir models: A case study on the effects of ice-cap unloading on shallow volcanic systems
Bakker R.R., FrehnerM., LupiM. (2016), How temperature-dependent elasticity alters host rock/magmatic reservoir models: A case study on the effects of ice-cap unloading on shallow volcanic systems, in Earth and Planetary Science Letters , 456, 16-25.
Ductile flow in sub-volcanic carbonate basement as the main control for edifice stability: New experimental insights
Richard R. Bakker Marie E.S. Violay Philip M. Benson and Sergio C. Vinciguerra (2015), Ductile flow in sub-volcanic carbonate basement as the main control for edifice stability: New experimental insights, in Earth and Planetary Science Letters, 430, 533-541.

Datasets

The propagation and seismicity of dyke injection, new experimental evidenceDYKE INJECTION ACOUSTIC EMISSION

Author Bakker, Richard R.; Fazio, Marco; Benson, Philip M.; Hess, Kai-Uwe; Dingwell, Donald B.
Publication date 16.03.2016
Persistent Identifier (PID) 0094-8276
Repository research-collection.ethz
Abstract
To reach the surface, dykes must overcome the inherent tensile strength of the country rock. As they do, they generate swarms of seismic signals, frequently used for forecasting. In this study we pressurize and inject molten acrylic into an encapsulating host rocks of (1) Etna basalt and (2) Comiso limestone, at 30 MPa of confining pressure. Fracture was achieved at 12 MPa for Etna basalt and 7.2 MPa for Comiso limestone. The generation of radial fractures was accompanied by acoustic emissions (AE) at a dominant frequency of 600 kHz. During “magma” movement in the dykes, AE events of approximately 150 kHz dominant frequency were recorded. We interpret our data using AE location and dominant frequency analysis, concluding that the seismicity associated with magma transport in dykes peaks during initial dyke creation but remains significant as long as magma movement continues. These results have important implications for seismic monitoring of active volcanoes.

Collaboration

Group / person Country
Types of collaboration
Earth Processes, Dept. Earth Sciences, Royal Holloway Great Britain and Northern Ireland (Europe)
- in-depth/constructive exchanges on approaches, methods or results
- Research Infrastructure
Experimental volcanology laboratory, Munich Germany (Europe)
- in-depth/constructive exchanges on approaches, methods or results
- Research Infrastructure

Scientific events

Active participation

Title Type of contribution Title of article or contribution Date Place Persons involved
Swiss Geoscience Meeting Poster Volcanoes with carbonate basements: understanding basement deformation and degassing phenomena. 21.11.2014 Fribourg, Switzerland Bakker Richard; Burg Jean-Pierre;
EURO-Conference on Rock Physics and Geomechanics Individual talk Tensile fracturing and dyking in volcano-tectonic settings, a laboratory approach. 11.05.2014 Aussois, France Benson Philip M.; Bakker Richard;
European Geophysical Union General Assembly Talk given at a conference Dyke propagation and tensile fracturing at high temperature and pressure, insights from experimental rock mechanics 27.04.2014 Vienna, Austria Bakker Richard; Benson Philip M.;
Scientific Conference, American GeoPhysical Union 2013 Poster Dyke emplacement and propagation: a new laboratory approach 13.12.2013 SanFrancisco, United States of America Benson Philip M.; Bakker Richard;
European Geophysical Union Individual talk Deforming Etna’s Basement: Implications for Edifice stability 13.05.2013 Vienna, Austria Benson Philip M.; Bakker Richard;
Swiss Geoscience Meeting Poster Tensile fracturing and dyking in volcano-tectonic settings, a laboratory approach. 16.11.2012 Bern, Switzerland Benson Philip M.; Bakker Richard;


Associated projects

Number Title Start Funding scheme
157772 HighSTEPS : HighStrainTEmperaturePressureSpeed 01.10.2015 R'EQUIP
144980 Manufacturing synthetic rocks in the Rock Deformation Laboratory, ETH: Hot Isostatic Press Upgrade (HIP UP) 01.12.2012 R'EQUIP

Abstract

This new project aims to quantify and simulate in the laboratory some of the key processes involved in the process of magma and melt intrusion into host rock masses. To achieve this goal we request funding for three years for one Ph.D. student, together with standard laboratory consumables and limited field expenses.This proposal continues and extends research that was initiated by the PI in 2005 that seek to investigate the characteristics of seismicity generated due to fluid flow in volcanic areas that are frequently observed prior to eruption. This rock-physics themed work subsequently evolved in 2009 by investigating how pore fluids in active geological regions may fracture the surrounding country rock through the process of hydrofracture. Such investigations are of broad significance to the geological community from both the pure research (e.g. ore body emplacement, hydrothermal circulation) as well as the applied geosciences (e.g. geothermal energy extraction and enhanced hydrocarbon recovery). However, previous work was either (a), limited to high temperatures under simple confined samples that are not truly representative of the scenario in the shallow crust, or (b), to modest confinement at room temperature. With the recent arrival of the PI at ETH Zurich, a unique opportunity now exists to close this gap by carrying out experiments at both higher temperatures and under confinement, in this new project on the topic of hydrofracture propagation and arrest and the associated coupled processes. Experimental rock deformation experiments will be performed at pressures to ~100 MPa (~4 km), and to temperatures of ~1200 °C using unique ‘nested’ samples comprising a molten conduit axial core fed by a reservoir. The temperature / pressure conditions are representative of shallow magma reservoirs and the associated feeder dyke systems. Research will be three-fold. Firstly we will explore the dependence and fracture mechanics behaviour of the outer material (shell) of country rock upon pressure and temperature and with respect to measured seismicity and material properties. Secondly, we will measure and analyse the magma propagation through the composite samples that use a range of alternative soft/hard rock layers to investigate under what conditions of pressure / temperature and rocks fracture property ratio that magma is observed to arrest, or deflect upon encountering such stress ‘barriers’. Finally, limited fieldwork will be conducted to obtain fresh samples of representative samples, such as Seljadour Basalt (Iceland), Neopolitan Yellow Tuff (Italy), and Lipary Rhyolite (Aeolian chain, Italy), as well as using samples synthesised via the Hot Isostatic Press installed at ETH Zurich. All of these laboratory data will be used as input to the Gudmundsson (2009) model for magma propagation and arrest in order to explore the key differences between uniaxial (unconfined) and triaxial (confined) scenarios. Thus we will provide, for the first time under in-situ conditions, an opportunity to calibrate such models, and to asses the conditions that magma bodies intrude the overburden, with application to ore bodies, geothermal energy extraction, and volcano-tectonics applications.
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