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Permeability enhancement from a hydraulic stimulation imaged with Ground Penetrating Radar
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  • Alexis Shakas,
  • Hansruedi Maurer,
  • Peter-Lasse Giertzuch,
  • Marian Hertrich,
  • Domenico Giardini,
  • Peter Meier
Alexis Shakas
Swiss Federal Institute of Technology in Zurich

Corresponding Author:alexis.shakas@sccer-soe.ethz.ch

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Hansruedi Maurer
Institute of Geophysics
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Peter-Lasse Giertzuch
Swiss Federal Institute of Technology in Zurich
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Marian Hertrich
Swiss Federal Institute of Technology in Zurich
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Domenico Giardini
ETH Z├╝rich
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Peter Meier
Geo-Energie Suisse AG
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Abstract

We present evidence of permeability enhancement from hydraulic stimulation experiments in fractured crystalline rock. A total of almost 10m3 was injected in two fractured intervals of a 300 m long borehole. Ground Penetrating Radar (GPR) measurements in the same borehole were carried out prior to and following the stimulation. The initial measurements revealed fractures in the vicinity of the borehole that could be traced up to distances of 50 meters away. The data measured post-stimulation were used in a difference-imaging approach to illuminate changes in the GPR reflections caused by the stimulations. The changes delineate the enhancement of a large and complex fracture network. These changes likely correspond to changes in local aperture, thus permeability. Our results indicate that borehole GPR yields unique information on subtle changes in hydraulic properties within a relatively large volume and provides a new perspective on the characterization and monitoring of deep geothermal reservoirs.
16 Sep 2020Published in Geophysical Research Letters volume 47 issue 17. 10.1029/2020GL088783