Seismic sources

Patent · 31 December 1991

OSTI ID:868392

Green, Michael A ^[1]; Cook, Neville G. W. ^[2]; McEvilly, Thomas V ^[3]; Majer, Ernest L ^[4]; Witherspoon, Paul A ^[3]

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1. Oakland, CA
2. Lafayette, CA
3. Berkeley, CA
4. El Cirrito, CA

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.

• Research Organization: Lawrence Berkeley National Laboratory (LBNL), Berkeley, CA
• DOE Contract Number: AC03-76SF00098
• Assignee: United States of America as represented by United States (Washington, DC)
• Patent Number(s): US 5131488
• OSTI ID: 868392
• Country of Publication: United States
• Language: English

Related Subjects

/181/367/
150
apparatus
armature
axis
borehole
borehole wall
causes
clamped
closely
controlled
degree
described
driven
driving
earth
electrically
electrically driven
element
elements
enables
energizing
fills
fixed
forces
generated
generation
heating
hydraulic
level
logitudinal
minute
operation
opposite
oscillate
pistons
placement
power
power level
press
pressure
pressure wave
pressure waves
pure
rapidly
reaction
relative
reservoir
rotor
rotor element
seismic
seismic source
seismic waves
shear
shear wave
shear waves
sources
stator
surrounding
surrounding earth
torsional
transmitted
walls
waves