[S02-5] New directions in anthropogenic seismicity studies I

[S02-5-05] Identifying pathways for gas and fluid migration caused by fracking processes, with the use of criteria defined in equivalent dimension phase spaces

^○Stanislaw Lasocki¹, Beata Orlecka-Sikora¹, Konstantinos Leptokaropoulos¹, Grzegorz Kwiatek², Patricia Martinez-Garzon², Paolo Capuano³, Simone Cesca² (1.Institute of Geophysics, Polish Academy of Sciences, Warsaw, Poland, 2.Helmholtz-Centre Potsdam GFZ German Research Centre for Geosciences, Potsdam, Germany, 3.AMRA – Analysis and Monitoring of Environmental Risk, Italy)

SHale gas Exploration and Exploitation Risks (SHEER, www.sheerproject.eu) project aims at assessing short and long-term risks associated with groundwater contamination, air pollution and induced seismicity. The severity of each of these depends strongly on the unexpected enhanced permeability pattern, which may develop as an unwanted by-product of the fracking processes and may become pathway for gas and fluid migration towards underground water reservoirs or the surface. An important part of SHEER is devoted to monitor and understand how far this enhanced permeability pattern will develop both in space and time. Here we present a novel approach for identifying pathways for gas and fluid migration based on the transformation to equivalent dimensions. The transformation converts a set of any original parameters of seismic events in a set of their equivalent dimensions, which are strictly comparable. The latter set builds a phase space, whose metrics is Euclidean. These features of equivalent dimensions make it possible to introduce any complex, multidimensional criteria for selecting seismic events. We present results of the analysis of an injection induced seismicity data from The Geysers geothermal field, which is used in SHEER as a proxy of seismicity accompanying shale gas operations. In addition to occurrence time, location and magnitude these seismic events are parameterized by moment tensors and spectral parameters. This allows to define and apply criteria for possible linking of fractures into gas migration pathways in a prescribed direction, based on fracture fault planes orientations, on closeness of locations, on sources radii and on angles between the fault planes.
This work was supported within SHEER: "Shale Gas Exploration and Exploitation Induced Risks" project funded from Horizon 2020 – R&I Framework Programme, call H2020-LCE-2014-1 and within statutory activities No3841/E-41/S/2017 of Ministry of Science and Higher Education of Poland.