Geosciences Spring 2022 Seminar Series
Peter Geiser
Friday April 22nd
12:30PM
Virtual: contact Christin.donnelly@uconn.edu for link
Fracture Seismic Mapping of the Crust’s GeoCritical Permeability Field
ABSTRACT
The highly heterogeneous permeability field of the Earth’s brittle crust has long been a bane of those seeking to extract its fluid resources. We discuss the geologic and geophysical evidence that Fracture Seismic Imaging (FSI), an advanced form of Seismic Emission Tomography (SET1) solves this problem by directly mapping the permeability field in its quantitative manifestation and temporal evolution. Further, we describe a permeability “mechanism” operating across the micro to macro scales. These results are placed in the context of the principles of critical state rock physics as they apply to the FSI method.
FSI signals originate from fracture propagation, the minute elastic vibrations of these fluid filled voids2 and the strain response of the rock all driven by the continual stress wave flux moving through the brittle crust. Passive observation, of both ambient and induced seismic data, is recorded using standard 3-D seismic reflection receiver technology. These data whose source is the rock itself, processed with FSI methods produce the 5D (Space, time, energy) permeability field map. Although sedimentary basins have a prominent role in our discussion, our current knowledge is that FSI permeability field maps can be made in all lower temperature (< 250o C), non-metamorphic environments including orogenic belts. While the maximum depth of all FSI data so far examined do not exceed 5 kms, the initial geological application of SET by Charles Archambeau in the early 80s, succeeded in imaging deformation at a depth of 20 kms, at or near the brittle/ductile transition.
For more information, contact: Christin Donnelly at christin.donnelly@uconn.edu