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Resolving Time Dependant Stress Variations through Analysis of Microseismicity Recorded During Hydraulic Fracturing
- Publisher: European Association of Geoscientists & Engineers
- Source: Conference Proceedings, 77th EAGE Conference and Exhibition 2015, Jun 2015, Volume 2015, cp-451-00564
Abstract
Hydraulic fracturing of shale reservoirs enhances productivity of reservoirs by propping open fractures in the reservoir. In order to map the extent of the successfully stimulated zones, microseismic monitoring is increasingly used; typical outputs of such monitoring efforts are the geometry of the microseismic event distribution. To relate these event distributions to production decline curves, geomechanical modelling of the injection using these event distributions as a constraint is frequently performed. However, a basic assumption of such efforts is that the stress regime under which the events are occurring is invariant. By using multiple-well recordings of microseismic events, the mechanisms of the microseismicity may be determined. These mechanisms are proportional to the strain rate (deformation) that is imparted to the medium at the point of rupture, and as such constrain the stress regime through the treatment. Observations indicate that the stress/strain conditions in the reservoir can be highly variable, implying that microseismicity needs to be coupled to geomechanical models at a more basic level, in that the dynamic stress regime controls both the occurrence of these events and the propagation of fluid and proppant in the reservoir.