--> Abstract: Future of Microseismic Analysis - Integration of Monitoring and Reservoir Simulation, by Leo Eisner, Vladimir Grechka, and Sherilyn Williams-Stroud; #90124 (2011)
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AAPG ANNUAL CONFERENCE AND EXHIBITION
Making the Next Giant Leap in Geosciences
April 10-13, 2011, Houston, Texas, USA

Future of Microseismic Analysis - Integration of Previous HitMonitoringNext Hit and Previous HitReservoirNext Hit Simulation

Leo Eisner1; Vladimir Grechka2; Sherilyn Williams-Stroud1

(1) MicroSeismic, Inc., Houston, TX.

(2) Shell Exploration & Production, Houston, TX.

Previous HitMonitoringNext Hit of microseismic events induced by Previous HitreservoirNext Hit stimulation has become a key aspect in evaluation of hydraulic fractures and their optimization. Future developments of this technology are dependent on improvements in multiple discipline areas, two of which are discussed in this study: better quantification of event locations along with the velocity model, and improved understanding and calibration of the type of rock failure responsible for the Previous HitseismicNext Hit events.

Currently, locations of microseismic events are used to infer the geometries of hydraulic fractures. These locations are inverted from Previous HitseismicNext Hit signals recorded by sensors either distributed at the surface or in dedicated Previous HitmonitoringNext Hit borehole(s). The accuracy and precision of the inverted locations depends on both the signal-to-noise ratios of Previous HitseismicNext Hit data and the spatial distribution of the receivers. While surface Previous HitmonitoringNext Hit usually suffers from low signal-to-noise ratio, the ability to place receivers in multiple azimuths and offsets allows for precise event location. On the other hand, downhole Previous HitmonitoringNext Hit provides robust detection due to a higher signal-to-noise ratio if an event is sufficiently close to the Previous HitmonitoringNext Hit borehole; however, precise location of events might be difficult, especially in the case of a single Previous HitmonitoringNext Hit well. Thus, integration of downhole and surface Previous HitmonitoringNext Hit may be beneficial to both methodologies.

Observed Previous HitseismicNext Hit waves carry information about the Previous HitreservoirNext Hit properties and the mechanisms of microseismic sources, allowing determination of the type of rock failure in addition to using microseismic event to infer hydraulic fracture geometry. Fracture stimulation models are often based on generating tensile fractures parallel to the maximum stress direction in the Previous HitreservoirNext Hit but analyses of the observed microseismic events are dominated by shear failure mechanisms. An assessment of whether the shear failure represents creation of new fractures or reactivation of the existing ones is often based on conceptual models with little data for validation. Analysis of data obtained from a microseismic Previous HitmonitoringNext Hit project where an image log was acquired in the treatment well allows validation of the model interpreted from the event locations and the inverted source mechanisms. Integration of source-mechanism analysis with information obtained from image logs leads to a better constrained Previous HitreservoirTop model populated with fractures away from the wellbore.