Anniina Kittilä Publications

Anniina Kittilä

PhD Student for Geothermal Energy and Geofluids

anniina_picture_231x301

Mailing Address
Anniina Kittilä
Geothermal Energy & Geofluids
Institute of Geophysics
NO F 51.1
Sonneggstrasse 5
CH-8092 Zurich Switzerland

Contact
Phone +41 44 6334041
Email anniina.kittila(at)erdw.ethz.ch

Administration
Dominique Ballarin Dolfin
Phone +41 44 632 3465
Email ballarin(at)ethz.ch

Publications

REFEREED PUBLICATIONS IN JOURNALS

3.  Kong, X.-Z., C. Deuber, A. Kittilä, M. Somogyvari, G. Mikutis, P. Bayer, W.J. Stark, and M.O. Saar Tomographic reservoir imaging with DNA-labeled silica nanotracers: The first field validation, Environmental Science &Technology, 52/23, pp. 13681-13689, 2018. Abstract
This study presents the first field validation of using DNA-labeled silica
nanoparticles as tracers to image subsurface reservoirs by travel time based tomography. During
a field campaign in Switzerland, we performed short-pulse tracer tests under a forced hydraulic
head gradient to conduct a multisource−multireceiver tracer test and tomographic inversion,
determining the two-dimensional hydraulic conductivity field between two vertical wells.
Together with three traditional solute dye tracers, we injected spherical silica nanotracers,
encoded with synthetic DNA molecules, which are protected by a silica layer against damage due
to chemicals, microorganisms, and enzymes. Temporal moment analyses of the recorded tracer
concentration breakthrough curves (BTCs) indicate higher mass recovery, less mean residence
time, and smaller dispersion of the DNA-labeled nanotracers, compared to solute dye tracers.
Importantly, travel time based tomography, using nanotracer BTCs, yields a satisfactory
hydraulic conductivity tomogram, validated by the dye tracer results and previous field
investigations. These advantages of DNA-labeled nanotracers, in comparison to traditional
solute dye tracers, make them well-suited for tomographic reservoir characterizations in fields such as hydrogeology, petroleum engineering, and geothermal energy, particularly with respect to resolving preferential flow paths or the heterogeneity of contact surfaces or by enabling source zone characterizations of dense nonaqueous phase liquids.
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2.  Amann, F., V. Gischig, K. Evans, et al., A. Kittilä, S. Wiemer, M.O. Saar, S. Löw, Th. Driesner, and H. Maurer The seismo-hydro-mechanical behaviour during deep geothermal reservoir stimulations: open questions tackled in a decameter-scale in-situ stimulation experiment, Solid Earth, 9, pp. 115-137, 2018. Abstract
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 studying such processes under controlled conditions. The review shows that research on reservoir stimulation for deep geothermal energy exploitation has been largely based on laboratory observations, large-scale projects and numerical models. Observations of full-scale reservoir stimulations have yielded important results. However, the limited access to the reservoir and limitations in the control on the experimental conditions during deep reservoir stimulations is insufficient to resolve the details of the hydromechanical processes that would enhance process understanding in a way that aids future stimulation design. Small-scale laboratory experiments provide fundamental insights into various processes relevant for enhanced geothermal energy, but suffer from (1) difficulties and uncertainties in upscaling the results to the field scale and (2) relatively homogeneous material and stress conditions that lead to an oversimplistic fracture flow and/or hydraulic fracture propagation behavior that is not representative of a heterogeneous reservoir. Thus, there is a need for intermediate-scale hydraulic stimulation experiments with high experimental control that bridge the various scales and for which access to the target rock mass with a comprehensive monitoring system is possible. The ISC experiment is designed to address open research questions in a naturally fractured and faulted crystalline rock mass at the Grimsel Test Site (Switzerland). Two hydraulic injection phases were executed to enhance the permeability of the rock mass. During the injection phases the rock mass deformation across fractures and within intact rock, the pore pressure distribution and propagation, and the microseismic response were monitored at a high spatial and temporal resolution.
/ Download
1.  Mikutis, G., C.A. Deuber, L. Schmid, A. Kittilä, N. Lobsiger, M. Puddu, D.O. Asgeirsson, R.N. Grass, M.O. Saar, and W.J. Stark Silica-encapsulated DNA-based tracers for aquifer characterization, Environmental Science & Technology, 52, pp. 12142-12152, 2018. Abstract
Environmental tracing is a direct way to characterize aquifers, evaluate the solute transfer parameter in underground reservoirs, and track contamination. By performing multitracer tests, and translating the tracer breakthrough times into tomographic maps, key parameters such as a reservoir’s effective porosity and permeability field may be obtained. DNA, with its modular design, allows the generation of a virtually unlimited number of distinguishable tracers. To overcome the insufficient DNA stability due to microbial activity, heat, and chemical stress, we present a method to encapsulated DNA into silica with control over the particle size. The reliability of DNA quantification is improved by the sample preservation with NaN3 and particle redispersion strategies. In both sand column and unconsolidated aquifer experiments, DNA-based particle tracers exhibited slightly earlier and sharper breakthrough than the traditional solute tracer uranine. The reason behind this observation is the size exclusion effect, whereby larger tracer particles are excluded from small pores, and are therefore transported with higher average velocity, which is pore size-dependent. Identical surface properties, and thus flow behavior, makes the new material an attractive tracer to characterize sandy groundwater reservoirs or to track multiple sources of contaminants with high spatial resolution.
/ Download

THESES

1.  Kittilä, A. Groundwater flow paths in the bedrock fracture zones revealed by using the stable isotopes of oxygen and hydrogen in the Talvivaara mine gypsum pond area, Northeastern Finland, MSc Thesis University of Helsinki, 68 pp., 2015. Abstract
Bedrock fracturing is considerably extensive and distinct in Finland, and the fractures that are open, conductive and interconnected usually control the groundwater flow paths in fractured bedrock. This highlights the importance of knowing the locations and hydraulic connections of water conducting fracture zones particularly in mining areas, because they can transport adverse substances outside the mining area. In this study, it is focused on examining possible hydraulic connections of bedrock groundwater by using the stable isotopes of oxygen (δ18O) and hydrogen (δ2H). The study was carried out in the Talvivaara mining area in Northeastern Finland alongside a project from the Geological Survey of Finland (GTK). After November 2012, when a leakage of acidic, metal-containing waste water occurred in the gypsum ponds, there was an urgent need to study the groundwater transport routes in the bedrock fractures. The aim was to find hydraulic connections between surface water and groundwater, and to study the flow of the groundwater in the fracture zones based on the different isotopic characteristics of waters from different sources and isotopic similarities. Most of the materials used in this study were obtained from the results of the project from the GTK. These materials included geophysical interpretations of the locations and water content of the main fracture zones and the results from the geochemical analyzes. Together with the interpretations of groundwater flow direction based on hydraulic heads these materials formed a frame for this study. The isotope composition of 39 water samples from bedrock wells, shallow wells and surface water was analyzed using cavity ring-down spectroscopy (CRDS) method. The surface waters were clearly distinguished based on their evident evaporation signal, but no significant such a signal was observed in the bedrock and shallow groundwaters. However, similarities between groundwater from different depths of same well were found, in addition to similarities between different wells along same fracture zones. Although the isotopes did not indicate surface water contamination, groundwater contamination with smaller amounts of water is possible, in which case the changes in isotope composition are not yet significant, while certain elements have elevated concentrations. A NE-SW oriented fracture zone passing in the center of the study area was concluded to have the most important role in collecting and transporting groundwater outside the mining area. More detailed interpretations would require regular sampling for a longer period of time to better distinguish naturally and artificially induced changes both in the isotopic but also geochemical compositions. Also the usage of packer tests possibly together with pumping tests would be useful in obtaining more comprehensive image of the groundwater flow in the fracture zones and their hydraulic connections.
/ Download

show/hide list of publications

REFEREED PUBLICATIONS IN JOURNALS

3.  Kong, X.-Z., C. Deuber, A. Kittilä, M. Somogyvari, G. Mikutis, P. Bayer, W.J. Stark, and M.O. Saar Tomographic reservoir imaging with DNA-labeled silica nanotracers: The first field validation, Environmental Science &Technology, 52/23, pp. 13681-13689, 2018. Abstract
This study presents the first field validation of using DNA-labeled silica
nanoparticles as tracers to image subsurface reservoirs by travel time based tomography. During
a field campaign in Switzerland, we performed short-pulse tracer tests under a forced hydraulic
head gradient to conduct a multisource−multireceiver tracer test and tomographic inversion,
determining the two-dimensional hydraulic conductivity field between two vertical wells.
Together with three traditional solute dye tracers, we injected spherical silica nanotracers,
encoded with synthetic DNA molecules, which are protected by a silica layer against damage due
to chemicals, microorganisms, and enzymes. Temporal moment analyses of the recorded tracer
concentration breakthrough curves (BTCs) indicate higher mass recovery, less mean residence
time, and smaller dispersion of the DNA-labeled nanotracers, compared to solute dye tracers.
Importantly, travel time based tomography, using nanotracer BTCs, yields a satisfactory
hydraulic conductivity tomogram, validated by the dye tracer results and previous field
investigations. These advantages of DNA-labeled nanotracers, in comparison to traditional
solute dye tracers, make them well-suited for tomographic reservoir characterizations in fields such as hydrogeology, petroleum engineering, and geothermal energy, particularly with respect to resolving preferential flow paths or the heterogeneity of contact surfaces or by enabling source zone characterizations of dense nonaqueous phase liquids.
/ Download
2.  Amann, F., V. Gischig, K. Evans, et al., A. Kittilä, S. Wiemer, M.O. Saar, S. Löw, Th. Driesner, and H. Maurer The seismo-hydro-mechanical behaviour during deep geothermal reservoir stimulations: open questions tackled in a decameter-scale in-situ stimulation experiment, Solid Earth, 9, pp. 115-137, 2018. Abstract
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 studying such processes under controlled conditions. The review shows that research on reservoir stimulation for deep geothermal energy exploitation has been largely based on laboratory observations, large-scale projects and numerical models. Observations of full-scale reservoir stimulations have yielded important results. However, the limited access to the reservoir and limitations in the control on the experimental conditions during deep reservoir stimulations is insufficient to resolve the details of the hydromechanical processes that would enhance process understanding in a way that aids future stimulation design. Small-scale laboratory experiments provide fundamental insights into various processes relevant for enhanced geothermal energy, but suffer from (1) difficulties and uncertainties in upscaling the results to the field scale and (2) relatively homogeneous material and stress conditions that lead to an oversimplistic fracture flow and/or hydraulic fracture propagation behavior that is not representative of a heterogeneous reservoir. Thus, there is a need for intermediate-scale hydraulic stimulation experiments with high experimental control that bridge the various scales and for which access to the target rock mass with a comprehensive monitoring system is possible. The ISC experiment is designed to address open research questions in a naturally fractured and faulted crystalline rock mass at the Grimsel Test Site (Switzerland). Two hydraulic injection phases were executed to enhance the permeability of the rock mass. During the injection phases the rock mass deformation across fractures and within intact rock, the pore pressure distribution and propagation, and the microseismic response were monitored at a high spatial and temporal resolution.
/ Download
1.  Mikutis, G., C.A. Deuber, L. Schmid, A. Kittilä, N. Lobsiger, M. Puddu, D.O. Asgeirsson, R.N. Grass, M.O. Saar, and W.J. Stark Silica-encapsulated DNA-based tracers for aquifer characterization, Environmental Science & Technology, 52, pp. 12142-12152, 2018. Abstract
Environmental tracing is a direct way to characterize aquifers, evaluate the solute transfer parameter in underground reservoirs, and track contamination. By performing multitracer tests, and translating the tracer breakthrough times into tomographic maps, key parameters such as a reservoir’s effective porosity and permeability field may be obtained. DNA, with its modular design, allows the generation of a virtually unlimited number of distinguishable tracers. To overcome the insufficient DNA stability due to microbial activity, heat, and chemical stress, we present a method to encapsulated DNA into silica with control over the particle size. The reliability of DNA quantification is improved by the sample preservation with NaN3 and particle redispersion strategies. In both sand column and unconsolidated aquifer experiments, DNA-based particle tracers exhibited slightly earlier and sharper breakthrough than the traditional solute tracer uranine. The reason behind this observation is the size exclusion effect, whereby larger tracer particles are excluded from small pores, and are therefore transported with higher average velocity, which is pore size-dependent. Identical surface properties, and thus flow behavior, makes the new material an attractive tracer to characterize sandy groundwater reservoirs or to track multiple sources of contaminants with high spatial resolution.
/ Download

THESES

1.  Kittilä, A. Groundwater flow paths in the bedrock fracture zones revealed by using the stable isotopes of oxygen and hydrogen in the Talvivaara mine gypsum pond area, Northeastern Finland, MSc Thesis University of Helsinki, 68 pp., 2015. Abstract
Bedrock fracturing is considerably extensive and distinct in Finland, and the fractures that are open, conductive and interconnected usually control the groundwater flow paths in fractured bedrock. This highlights the importance of knowing the locations and hydraulic connections of water conducting fracture zones particularly in mining areas, because they can transport adverse substances outside the mining area. In this study, it is focused on examining possible hydraulic connections of bedrock groundwater by using the stable isotopes of oxygen (δ18O) and hydrogen (δ2H). The study was carried out in the Talvivaara mining area in Northeastern Finland alongside a project from the Geological Survey of Finland (GTK). After November 2012, when a leakage of acidic, metal-containing waste water occurred in the gypsum ponds, there was an urgent need to study the groundwater transport routes in the bedrock fractures. The aim was to find hydraulic connections between surface water and groundwater, and to study the flow of the groundwater in the fracture zones based on the different isotopic characteristics of waters from different sources and isotopic similarities. Most of the materials used in this study were obtained from the results of the project from the GTK. These materials included geophysical interpretations of the locations and water content of the main fracture zones and the results from the geochemical analyzes. Together with the interpretations of groundwater flow direction based on hydraulic heads these materials formed a frame for this study. The isotope composition of 39 water samples from bedrock wells, shallow wells and surface water was analyzed using cavity ring-down spectroscopy (CRDS) method. The surface waters were clearly distinguished based on their evident evaporation signal, but no significant such a signal was observed in the bedrock and shallow groundwaters. However, similarities between groundwater from different depths of same well were found, in addition to similarities between different wells along same fracture zones. Although the isotopes did not indicate surface water contamination, groundwater contamination with smaller amounts of water is possible, in which case the changes in isotope composition are not yet significant, while certain elements have elevated concentrations. A NE-SW oriented fracture zone passing in the center of the study area was concluded to have the most important role in collecting and transporting groundwater outside the mining area. More detailed interpretations would require regular sampling for a longer period of time to better distinguish naturally and artificially induced changes both in the isotopic but also geochemical compositions. Also the usage of packer tests possibly together with pumping tests would be useful in obtaining more comprehensive image of the groundwater flow in the fracture zones and their hydraulic connections.
/ Download