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Microseismic Monitoring of Hydraulic Fracture Treatments: Geology Matters - Acquisition, Processing and Interpretation Examples.

Joël Le Calvez, Géraldine Haas, Leah Hogarth, and John Woerpel
Schlumberger, Houston, TX

In the last decade, hydraulic fracturing operations used to stimulate production in unconventional reservoirs have increased exponentially. Ultimately, a successful stimulation is proven by production. However, most geoscientists and engineers use quantity, coverage, and microseismic monitoring data to initially assess stimulation effectiveness. Many factors affect how microseismicity is generated and interpreted. Using various treatment and monitoring configurations, we demonstrate that ignoring the geology (e.g., lithology, stress contrast, natural fracturing, structural or depositional dip, faulting) and the associated rock properties (e.g., noise, slowness, anisotropy, attenuation) can potentially lead to poor stimulation and well placement, inadequate monitoring configurations, inconsistent processing approaches, and misleading interpretations. Thus, geology matters for validation of the exploration and production effort. For example, a producer well landed relative to lithology, but not oriented according to the local stress field will likely not be stimulated as effectively as a properly oriented one. Moreover, if a well is oriented adequately in terms of local stress regime, but lateral variations in stress contrasts are ignored, perforation placement and stimulation will likely be ineffective. If a lateral is landed in a dipping formation, but recorded acoustic emissions are processed assuming a flat velocity model, mapped events will be erroneously located. If a formation is naturally quiet but monitoring geophones are positioned in surrounding noisy rocks, quality of the monitored signals and resulting processing is not optimum. If the velocity model used to process the recorded acoustic emissions is inappropriately blocked, the geological reality is not properly represented, resulting in a biased interpretation.


AAPG Search and Discovery Article #90152©2012 AAPG Southwest Section Meeting, Fort Worth, Texas, 19-22 May 2012