From Bureau of Economic Geology, The
University of Texas at Austin (www.beg.utexas.edu).
For more information, please contact the author.
Bureau Seminar, October 5, 2012
Tomographic Fracture Imaging: A new microseismic technology
Alfred Alcazette, PhD
Global Geographic Services
This presentation will:
Describe a new, patented, surface-based microseismic method that directly images induced and natural fracture flow paths in the reservoir as complex surfaces, not dots-in-a-box.
Present an extensive data set from a 15-well project that validates Tomographic Fracture Images (TFIs) with independent data including: conventional borehole microseismic data, radioactive frac tracers, chemical frac tracers, borehole images, open- and cased-hole production logs, pore-pressure measurements, geochemical fingerprinting, and geomechanical analysis.
Review applications of TFIs, which include Discrete Fracture Network frac and reservoir simulation, field development planning, well spacing analysis, and even exploration via quiet-time monitoring of ambient microseismic activity on 3D reflection grids.
The method is orders of magnitude more sensitive than traditional microseismic methods because it looks at cumulative signal from each voxel over time rather than attempting to discriminate individual microseismic events. However, conventional hypocenters and microearthquake focal mechanisms are also extracted from the field data.
Eagle Ford example. Oblique view of a wellbore with microearthquake hypocenters (blue dots) and one-voxel-thick depth-slice of the Tomographic Fracture Image™ of a stage. The depth of the slice is at the level of the wellbore. Gray areas with white outline show the footprint of the entire three-dimensional TFI in map view. The TFI is colored by signal intensity. Blue dots on the wellbore show the perf locations. The well was drilled parallel to the minimum principal stress. Note that the frac propagated symmetrically outward from the wellbore until it intersected a subseismic natural fracture that captured the frac and drained it into a seismically-mappable fault.