The Loránd Eötvös Award^*) 2017 is presented to

Nicolas Hummel
and his co-author S. A. Shapiro

For their paper ´Back front of seismicity induced by non-linear pore pressure diffusion´, published in Geophysical Prospecting, volume 64, issue 1,
January 2016, pp. 170-191.

Diffusion of a pore-pressure perturbation from a borehole fluid-injection source triggers microseismic events whose spatio-temporal evolution is interpretable in terms of the diffusivity and hence permeability of the rock mass. The seismicity continues after injection ceases and there is a ‘back front’ corresponding to the distance from the injection point that seismicity terminates at a given time after fluid injection ceases. In the case of hydraulic fracturing, permeability becomes strongly pressure dependent and anisotropic, and the diffusion is no longer linear. Hummel and Shapiro extend our understanding of the effect of fluid injection, including hydraulic fracturing and geothermal injection, on the distribution of induced seismicity in space and time. Comparing simulations with measured data, the authors show that the spatio-temporal characteristics of the event clouds can reveal a non-linear dependence of permeability on pressure, allowing the diffusivity tensor to be estimated, with economic benefit. The back front is a particularly strong diagnostic of non-linear diffusion in the rock mass.

Paris, 12 June 2017

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*) Best Paper Award
The Loránd Eötvös Award is presented to the author(s) of the best paper published in Geophysical Prospecting in the calendar year preceding the award. The paper should be of high scientific standard and should represent a significant contribution or an outstanding tutorial in one or more of the disciplines in our Association.

The Eötvös Award consists of a certificate as well as a specially bound copy of the issue in which the pertinent paper appears.