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Zurich, Switzerland

Eaton D.W.,University of Calgary | van der Baan M.,University of Alberta | Birkelo B.,Spectraseis | Tary J.-B.,University of Alberta
Geophysical Journal International | Year: 2014

Using formulae for both tensile and shear sources, we investigate spectral characteristics of microearthquakes induced by hydraulic fracturing, with application to passive-seismic data recorded during a multistage treatment programme in western Canada. For small moment magnitudes (Mw < 0), reliable determination of corner frequency requires accurate knowledge of QP and QS, although spectral estimates of magnitude are relatively unaffected by uncertainty in seismic attenuation. Here, we estimate QP and QS using spectral ratios derived from perforation shots. Of the microseismic events analysed during the hydraulic-fracture treatment, 17 of 20 exhibit an S/P spectral ratio < 5, which is consistent with tensile failure. In addition, four microseismic events are characterized by a modulating source spectrum containing quasi-periodic notches.We interpret this spectral character to reflect a complex rupture pattern that involves rapid (5-8 ms) opening and closing of tensile cracks. In general, for tensile rupture on a penny-shaped crack, our model predicts that source radius (a) is related to moment magnitude (Mw) and internal fluid pressure within the fracture (Pi) by a simple empirical scaling relation: log10(a) = [9 - log102]/3 + 0.5Mw - log10(Pi)/3. © The Authors 2014. Published by Oxford University Press on behalf of The Royal Astronomical Society. Source


A method and system for processing synchronous array seismic data includes acquiring synchronous passive seismic data from a plurality of sensors to obtain synchronized array measurements. A reverse-time data propagation process is applied to the synchronized array measurements to obtain a plurality of dynamic particle parameters associated with subsurface locations. Imaging conditions are applied to the dynamic particle parameters to obtain image values associated with subsurface energy source locations.


Patent
Spectraseis | Date: 2011-09-25

A method and system for processing synchronous array seismic data includes acquiring synchronous passive seismic data from a plurality of sensors to obtain synchronized array measurements. A reverse-time data process is applied to the synchronized array measurements to obtain a plurality of dynamic particle parameters associated with subsurface locations. These dynamic particle parameters are stored in a form for display. Maximum values of the dynamic particle parameters may be interpreted as reservoir locations. The dynamic particle parameters may be particle displacement values, particle velocity values, particle acceleration values or particle pressure values. The sensors may be three-component sensors. Zero-phase frequency filtering of different ranges of interest may be applied. The data may be resampled to facilitate efficient data processing.


Patent
Spectraseis | Date: 2011-09-26

A method and system for processing synchronous array seismic data includes acquiring synchronous passive seismic data from a plurality of sensors to obtain synchronized array measurements. A reverse-time data propagation process is applied to the synchronized array measurements to obtain a plurality of dynamic particle parameters associated with subsurface locations. Imaging conditions are applied to obtain imaging values that may be summed or stacked to obtain a time reverse image attribute. A volume of imaging values may be scaled by a non-signal noise function to obtain a modified image that is compensated for noise effects.


Patent
Spectraseis | Date: 2011-09-26

A method and system for processing synchronous array seismic data includes acquiring synchronous passive seismic data from a plurality of sensors to obtain synchronized array measurements. A reverse-time data propagation process is applied to the synchronized array measurements to obtain a plurality of dynamic particle parameters associated with subsurface locations. Imaging conditions are applied to obtain imaging values that may be summed or stacked to obtain a time reverse image attribute. A volume of imaging values may be scaled by a non-signal noise function to obtain a modified image that is compensated for noise effects.

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