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Using borehole breakouts to constrain the complete stress tensor: Results from the Sijan Deep Drilling Project and offshore Santa Maria Basin, California

Zajac, Blair J. and Stock, Joann M. (1997) Using borehole breakouts to constrain the complete stress tensor: Results from the Sijan Deep Drilling Project and offshore Santa Maria Basin, California. Journal of Geophysical Research B, 102 (B5). pp. 10083-10100. ISSN 0148-0227. https://resolver.caltech.edu/CaltechAUTHORS:20140415-112237965

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Abstract

We use borehole breakouts in nonvertical drill holes to constrain the directions of the three principal stresses and their relative magnitudes. In this paper we start by modifying previously published breakout selection criteria to work with highly deviated borehole data. We present a forward modeling technique using genetic algorithms and a nongradient N-dimensional optimizer to find the best fitting stress state for a set of breakout data. The stress state is parameterized by three Euler angles and the stress state ratio ø. A technique is developed to determine the 95% confidence weighted misfit between a model and the data. We then map out the 95% misfit confidence limits on the best fitting stress state. This technique is applied to data published by Qian and Pedersen [1991]. Removing their constraint of a vertical principal stress direction reduces the misfit between the stress state and the breakout data. We find that the best fitting stress state they report with a vertical principal stress direction lies outside our 95% confidence limits. We also invert breakouts in the offshore Santa Maria Basin, California. These data show a "thrust faulting" stress state with the maximum principal stress, S_1, at N148.5°E plunging 31.5°. The 95% confidence range for the azimuth of S_1 ranges from N143.0°E to N198.1°E. The stress ratio ø was found to be 0.82l^1_(0.584).


Item Type:Article
Related URLs:
URLURL TypeDescription
http://dx.doi.org/10.1029/96JB03914DOIArticle
http://onlinelibrary.wiley.com/doi/10.1029/96JB03914/abstractPublisherArticle
ORCID:
AuthorORCID
Stock, Joann M.0000-0003-4816-7865
Additional Information:© 1997 American Geophysical Union. Manuscript Accepted: 11 Dec 1996; Manuscript Received: 5 Aug 1996. The authors thank Julie Shemeta for providing a lot of help with this work, Jerry Lohr for releasing the Santa Maria data to us, and Torch Operating Company for allowing us to publish the data. We acknowledge Leonid Germanovich, Bezalel Haimson, and Pavel Peška for their constructive reviews of this paper. We also thank Wessel and Smith [1995] for creating the GMT plotting tools. This work was supported by the National Earthquake Hazards Reduction Program of the U.S. Geological Survey (USGS) and by NSF grant EAR-9296102 for J. M. Stock. Research was supported by the USGS, Department of the Interior, under USGS award 1434-93-G-2297. The views and conclusions contained in this document are those of the authors and should not be interpreted as necessarily representing the official policies, either expressed or implied, of the U.S. government. Caltech Seismological Laboratory Contribution Number 5729.
Group:Seismological Laboratory
Funders:
Funding AgencyGrant Number
USGS National Earthquake Hazards Reduction ProgramUNSPECIFIED
NSF Cooperative AgreementEAR-9296102
USGS1434-93-G-2297
Subject Keywords:Instruments and techniques; Stresses: crust and lithosphere
Other Numbering System:
Other Numbering System NameOther Numbering System ID
Caltech Division of Geological and Planetary Sciences5729
Issue or Number:B5
Record Number:CaltechAUTHORS:20140415-112237965
Persistent URL:https://resolver.caltech.edu/CaltechAUTHORS:20140415-112237965
Official Citation:Zajac, B. J., and J. M. Stock (1997), Using borehole breakouts to constrain the complete stress tensor: Results from the Sijan Deep Drilling Project and offshore Santa Maria Basin, California, J. Geophys. Res., 102(B5), 10083–10100, doi:10.1029/96JB03914.
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:44954
Collection:CaltechAUTHORS
Deposited By: Aucoeur Ngo
Deposited On:18 Apr 2014 16:29
Last Modified:03 Oct 2019 06:24

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