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Identification of brittle/ductile areas in unconventional reservoirs using seismic and microseismic data; application to the Barnett Shale

Roderick Perez Altamar and Kurt J. Marfurt
Identification of brittle/ductile areas in unconventional reservoirs using seismic and microseismic data; application to the Barnett Shale
Interpretation (Tulsa) (November 2015) 3 (4): T233-T243

Abstract

Brittleness in unconventional reservoirs is mainly controlled by mineralogy, and it increases with quartz and dolomite content, whereas an increase in the clay content represents an increase in ductility. To generate regional brittleness maps, we have correlated the mineralogy-based brittleness index to elastic parameters measured from well logs. This correlation can then be used to predict the brittleness from surface seismic elastic parameter estimates of lambda rho and mu rho . We applied the workflow to a 3D seismic survey acquired in an area where more than 400 wells were drilled and hydraulically fractured prior to seismic acquisition. Combining lambda rho and mu rho into a single 3D volume allowed the combination of both attributes into a single 3D volume, which can be converted to brittleness using a template based on the well log and core data. Neither of these seismic estimates were direct measures of reservoir completion quality. We, therefore, used production logs and extracted surface seismic estimates at microseismic event locations to analyze the completion effectiveness along several horizontal wellbores in the reservoir. We defined four petrotypes in lambda rho and mu rho space depending on their brittleness and gas saturation, and we found that most of the microseismic events fell into the zone described as brittle in the lambda rho -mu rho crossplots. These observations supported the well-known idea that regardless of where the well was perforated, microseismic events appeared to preferentially grow toward the more brittle areas, suggesting the growth of hydraulic fractures into the brittle petrotype.


ISSN: 2324-8858
EISSN: 2324-8866
Serial Title: Interpretation (Tulsa)
Serial Volume: 3
Serial Issue: 4
Title: Identification of brittle/ductile areas in unconventional reservoirs using seismic and microseismic data; application to the Barnett Shale
Affiliation: University of Oklahoma, ConocoPhillips School of Geology and Geophysics, Norman, OK, United States
Pages: T233-T243
Published: 201511
Text Language: English
Publisher: Society of Exploration Geophysicists, Tulsa, OK, United States
References: 27
Accession Number: 2016-007422
Categories: Economic geology, geology of energy sourcesApplied geophysics
Document Type: Serial
Bibliographic Level: Analytic
Annotation: Includes appendix
Illustration Description: sects., sketch maps
N25°45'00" - N36°30'00", W106°30'00" - W93°30'00"
Country of Publication: United States
Secondary Affiliation: GeoRef, Copyright 2017, American Geosciences Institute. Reference includes data from GeoScienceWorld, Alexandria, VA, United States. Reference includes data supplied by Society of Exploration Geophysicists, Tulsa, OK, United States
Update Code: 201604
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