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Hunt L.,Fairborne Energy | Reynolds S.,Fairborne Energy | Brown T.,Fairborne Energy | Hadley S.,Fairborne Energy | And 2 more authors.
Leading Edge (Tulsa, OK) | Year: 2010

These experiments illustrate that the AVAZ, VVAz, and curvature attributes correlate strongly with image log fracturedensity, and should be valid predictors of fractures in the Nordegg of this area. Similar observations were made using the microseismic data, a less direct validator of fracture prediction, also exhibited strong correlations. The large,spatially distributed sample size and similar support make microseismic events an intriguing data element to compare and cross-validate with surface seismic fracture predictors. The comparison of microseismic to surface seismic should be carried out with other data to determine if the results are repeatable. Further experiments may reveal how important the wellbore orientation and hydraulic fracture orientation were with reference to hmax and the orientation of the preexisting natural fractures. This work indicated that AVAz was the best single predictor of fracture density, although curvature attributes were almost as good. We also observed that despite the predictive correlations, significant scatter remained in the data comparisons. That scatter likely has implications to our data quality as well as the theoretical limitations of our methods. In consideration of this, we attempted to use com binations of the attributes in multilinear and crossplotting approaches. These results were most accurate when AVAz and curvature were used together. The advantage of using these attributes together may lie in the areas of validity for each attribute: AVAz can directly detect fractures, but may fail in hinge zones where multiple fracture sets are most likely to exist, while the curvature attribute identifies the hinge zones, but may not infer the fractures that exist in less obviously deformed areas. A surprising conclusion from this work was that the coherence attribute did not predict fracture density or microseismic event moments for the Nordegg in this area. For the kinds of fractures that exist in the Nordegg of this area, AVAz and curvature are a more useful combination than coherence and curvature, which have been used to advantage in other areas. © 2010 Society of Exploration Geophysicists.

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