Seismic sources

Patent · Wed Jan 01 00:00:00 EST 1992

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 (United States)
• 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

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
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