Resonances are identified in spectrograms computed from passive seismic and are used to select data for use in mapping permeable fractures. The resonances are both dispersive and non-dispersive. Dispersive resonances change frequency with time and dominate during the startup and early times of pumping while non-dispersive resonances are constant frequency versus time and dominate later in the frack pumping. Both types of resonance occur at all times. The resonance patterns depend on fracture length and aperture and on whether the fracture follows the closed crack model or the turbulent flow model. During pumping the resonance patterns are sensitive to changes in the pressure and slurry rate. The passive signals emitted during the pressure buildup before formation breakdown map the permeable fractures that are in communication with the well. After formation breakdown, turbulent flow in the open fractures near the well dominates the passive signal and maps the fractures that are opened by the pumping. The relationship between resonance and micro-earthquakes is demonstrated in passive data recorded for a deep geothermal well.
Presentation Date: Wednesday, September 18, 2019
Session Start Time: 8:30 AM
Presentation Start Time: 10:10 AM
Presentation Type: Oral