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Title: Seismic sources

Abstract

Apparatus is described for placement in a borehole in the earth, which enables the generation of closely controlled seismic waves from the borehole. Pure torsional shear waves are generated by an apparatus which includes a stator element fixed to the borehole walls and a rotor element which is electrically driven to rapidly oscillate on the stator element to cause reaction forces transmitted through the borehole walls to the surrounding earth. Logitudinal shear waves are generated by an armature that is driven to rapidly oscillate along the axis of the borehole relative to a stator that is clamped to the borehole, to cause reaction forces transmitted to the surrounding earth. Pressure waves are generated by electrically driving pistons that press against opposite ends of a hydraulic reservoir that fills the borehole. High power is generated by energizing the elements at a power level that causes heating to over 150.degree. C. within one minute of operation, but energizing the elements for no more than about one minute.

Inventors:
 [1];  [2];  [3];  [4];  [3]
  1. (Oakland, CA)
  2. (Lafayette, CA)
  3. (Berkeley, CA)
  4. (El Cirrito, CA)
Issue Date:
Research Org.:
Lawrence Berkeley National Laboratory (LBNL), Berkeley, CA
OSTI Identifier:
868392
Patent Number(s):
5131488
Assignee:
United States of America as represented by United States (Washington, DC) LBNL
DOE Contract Number:  
AC03-76SF00098
Resource Type:
Patent
Country of Publication:
United States
Language:
English
Subject:
seismic; sources; apparatus; described; placement; borehole; earth; enables; generation; closely; controlled; waves; pure; torsional; shear; generated; stator; element; fixed; walls; rotor; electrically; driven; rapidly; oscillate; reaction; forces; transmitted; surrounding; logitudinal; armature; axis; relative; clamped; pressure; driving; pistons; press; opposite; hydraulic; reservoir; fills; power; energizing; elements; level; causes; heating; 150; degree; minute; operation; rotor element; surrounding earth; shear waves; pressure waves; shear wave; power level; pressure wave; borehole wall; seismic source; seismic waves; electrically driven; /181/367/

Citation Formats

Green, Michael A., Cook, Neville G. W., McEvilly, Thomas V., Majer, Ernest L., and Witherspoon, Paul A. Seismic sources. United States: N. p., 1992. Web.
Green, Michael A., Cook, Neville G. W., McEvilly, Thomas V., Majer, Ernest L., & Witherspoon, Paul A. Seismic sources. United States.
Green, Michael A., Cook, Neville G. W., McEvilly, Thomas V., Majer, Ernest L., and Witherspoon, Paul A. Wed . "Seismic sources". United States. https://www.osti.gov/servlets/purl/868392.
@article{osti_868392,
title = {Seismic sources},
author = {Green, Michael A. and Cook, Neville G. W. and McEvilly, Thomas V. and Majer, Ernest L. and Witherspoon, Paul A.},
abstractNote = {Apparatus is described for placement in a borehole in the earth, which enables the generation of closely controlled seismic waves from the borehole. Pure torsional shear waves are generated by an apparatus which includes a stator element fixed to the borehole walls and a rotor element which is electrically driven to rapidly oscillate on the stator element to cause reaction forces transmitted through the borehole walls to the surrounding earth. Logitudinal shear waves are generated by an armature that is driven to rapidly oscillate along the axis of the borehole relative to a stator that is clamped to the borehole, to cause reaction forces transmitted to the surrounding earth. Pressure waves are generated by electrically driving pistons that press against opposite ends of a hydraulic reservoir that fills the borehole. High power is generated by energizing the elements at a power level that causes heating to over 150.degree. C. within one minute of operation, but energizing the elements for no more than about one minute.},
doi = {},
journal = {},
number = ,
volume = ,
place = {United States},
year = {1992},
month = {1}
}

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