Induced Seismicity in Large-scale Mining in the Kola Peninsula and Monitoring to Reveal Informative Precursors

1996 ◽  
pp. 263-276
Author(s):  
N. N. Melnikov ◽  
A. A. Kozyrev ◽  
V. I. Panin
1996 ◽  
Vol 147 (2) ◽  
pp. 263-276 ◽  
Author(s):  
N. N. Melnikov ◽  
A. A. Kozyrev ◽  
V. I. Panin

2020 ◽  
Vol 222 (1) ◽  
pp. 189-206 ◽  
Author(s):  
Peter Niemz ◽  
Simone Cesca ◽  
Sebastian Heimann ◽  
Francesco Grigoli ◽  
Sebastian von Specht ◽  
...  

SUMMARY Understanding fracturing processes and the hydromechanical relation to induced seismicity is a key question for enhanced geothermal systems (EGS). Commonly massive fluid injection, predominately causing hydroshearing, are used in large-scale EGS but also hydraulic fracturing approaches were discussed. To evaluate the applicability of hydraulic fracturing techniques in EGS, six in situ, multistage hydraulic fracturing experiments with three different injection schemes were performed under controlled conditions in crystalline rock at the Äspö Hard Rock Laboratory (Sweden). During the experiments the near-field ground motion was continuously recorded by 11 piezoelectric borehole sensors with a sampling rate of 1 MHz. The sensor network covered a volume of 30×30×30 m around a horizontal, 28-m-long injection borehole at a depth of 410 m. To extract and characterize massive, induced, high-frequency acoustic emission (AE) activity from continuous recordings, a semi-automated workflow was developed relying on full waveform based detection, classification and location procedures. The approach extended the AE catalogue from 196 triggered events in previous studies to more than 19 600 located AEs. The enhanced catalogue, for the first time, allows a detailed analysis of induced seismicity during single hydraulic fracturing experiments, including the individual fracturing stages and the comparison between injection schemes. Beside the detailed study of the spatio-temporal patterns, event clusters and the growth of seismic clouds, we estimate relative magnitudes and b-values of AEs for conventional, cyclic progressive and dynamic pulse injection schemes, the latter two being fatigue hydraulic fracturing techniques. While the conventional fracturing leads to AE patterns clustered in planar regions, indicating the generation of a single main fracture plane, the cyclic progressive injection scheme results in a more diffuse, cloud-like AE distribution, indicating the activation of a more complex fracture network. For a given amount of hydraulic energy (pressure multiplied by injected volume) pumped into the system, the cyclic progressive scheme is characterized by a lower rate of seismicity, lower maximum magnitudes and significantly larger b-values, implying an increased number of small events relative to the large ones. To our knowledge, this is the first direct comparison of high resolution seismicity in a mine-scale experiment induced by different hydraulic fracturing schemes.


Author(s):  
Anatoly Kozyrev ◽  
Viktor Panin ◽  
Iuliia Fedotova

2017 ◽  
Vol 18 (7) ◽  
pp. 2467-2485 ◽  
Author(s):  
Mirko van der Baan ◽  
Frank J. Calixto

2013 ◽  
pp. 112-124 ◽  
Author(s):  
A. R. Loshkareva ◽  
N. E. Koroleva

Large-scale vegetation mapping of key area of 1400 km2 in forest-tundra zone in the middle flow of Teriberkariver (Kola Peninsula) was conducted on the base of satellite images, topographic maps and field geobotanical investigations. Study of Landsat TM images local spectral characteristics and syntaxonomical analysis of vegetation demonstrated that satellite images with 30 m spatial resolution and 6-bands spectral resolution alone can't be used for automatical large-scale classification of forest-tundra zone vegetation. Map of vegetation in scale 1:50 000 resulted from manual processing of both hypsometry and spectral characteristic, on the base of field work points with description of vegetation. Legend of mapped units contains 2 types for tundra, 5 ones for mountain birch forest and 4 ones for wetlands. Quality and correctness of the map were verified by satellite image of extra high spatial resolution Quick Bird (0,65 m/pixel) and aerial photograph for this territory. The map illustrated that distribution of vegetation is primarily caused by unevenness of relief. Timberline lies at 220-240 m a.s.l., altitudinal distances across mountain birch forest and tundra zones are about 40-60 m, tundra vegetation occurs on moraine hills and bedrocks slopes and summits. Pounikkos flark-and-mounds, tuft-and-fen bog complexes occur from 170 to 240 m.s.l. in depressions and valleys. Proportion of tundra vegetation is about 40%, mountain birch forest – 30%, wetlands – 20%, lakes, rivers and springs take 10% of area investigated.


2020 ◽  
Author(s):  
Mohsen Goudarzi ◽  
Ylona van Dinther ◽  
Meng Li ◽  
René de Borst ◽  
Casper Pranger ◽  
...  

<p>Induced seismicity as a result of natural gas production is a major challenge from both an industrial and a societal perspective. The compaction caused by gas production leads to changes of the effective pressure fields in the reservoir and stress redistributions occur particularly in the surrounding faults. In addition, the strong coupling between fluid flow and solid rock deformations and the role of fluid flow regarding the frictional properties of the faults necessitate a coupled and comprehensive modeling framework. A general and fully coupled thermo-hydro-mechanical finite difference formulation is developed herein and the results are verified against numerical benchmarks. A visco-elasto-plastic rheological behavior is assumed for the bulk material and a return-mapping algorithm is implemented for accurate simulation of the stress evolution. The geometrical features of the faults are incorporated into a regularized continuum framework, while the response of the fault zone is governed by a rate-and-state-dependent friction model. Numerical simulations are provided for large-scale problems and their efficiency is assured through the evaluation of the consistently linearized systems of equations along with the use of advanced numerical solvers and parallel computing. Although the proposed framework is a step towards the modeling of earthquake sequences for induced seismicity applications, the features of the numerical model are highlighted for other applications, including seismic events in subduction settings where the role of fluid flow inside the faults is considerable. Another application of the present, fully coupled hydro-thermo-mechanical formulation is the prediction of the fluid pressurization phenomena, where the frictional heating increases the magnitude of the pore fluid pressure inside the faults, and the resultant degradation of dynamic frictional strength is naturally captured. </p>


Minerals ◽  
2020 ◽  
Vol 10 (2) ◽  
pp. 186 ◽  
Author(s):  
Pavel A. Serov ◽  
Tamara B. Bayanova ◽  
Ekaterina N. Steshenko ◽  
Evgeniy L. Kunakkuzin ◽  
Elena S. Borisenko

The article presents new Sm–Nd and U–Pb geochronological data on rocks of the poorly studied Pados-Tundra Cr-bearing complex. It is part of the Notozero mafic–ultramafic complex (western Kola Peninsula) and occurs at the border of the Paleoproterozoic Lapland Granulite Belt and the Archean Belomorian composite terrain. The Pados-Tundra complex hosts two major zones, the Dunite and Orthopyroxenite Blocks. Dunites are associated with four levels of chromite mineralization. Isotope Sm–Nd studies of dunites, harzburgites, and orthopyroxenites from the central part of the complex have been carried out. The isochron Sm–Nd age on 11 whole-rock samples from a rhythmically layered series of the complex is 2485 ± 38 Ma; the mineral Sm–Nd isochron for harzburgites shows the age of 2475 ± 38 Ma. It corresponds with the time of large-scale rifting that originated in the Fennoscandian Shield. When the rhythmically layered series of the intrusion and its chromite mineralization were formed, hornblendite dykes intruded. The U–Pb and Sm–Nd research has estimated their age at ca. 2080 Ma, which is likely to correspond with the occurrence of the Lapland–Kola Ocean. According to isotope Sm–Nd dating on metamorphic minerals (rutile, amphibole), the age of postmetamorphic cooling of rocks in the complex to 650–600 °C is 1872 ± 76 Ma. The U–Pb age on rutile from a hornblendite dyke (1804 ± 10 Ma) indicates further cooling to 450–400 °C. The conducted research has determined the early Proterozoic age of rocks in the rhythmically layered series in the Pados-Tundra complex. It is close to the age of the Paleoproterozoic ore magmatic system in the Fennoscandian Shield that developed 2.53–2.40 Ga ago. Later episodes of alterations in rocks are directly related to main metamorphic episodes in the region at the turn of 1.9 Ga. Results of the current study expand the geography of the vast Paleoproterozoic East Scandinavian Large Igneous Province and can be applied for further studies of similar mafic–ultramafic complexes.


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