Abstract Vibrator apparatus induces vibrations in an earth formation so that the nature of the earth formation can be determined from its effect on the induced vibrations. A sine wave voltage is provided having a variable frequency sweep. The voltage is phase shifted and summed with feedback signals. The sum signal is then used to control a torque motor. The motor controls a hydraulic valve which provides a hydraulic output to a cylinder to control the movement of a pad against the earth''s formation. The hydraulic valve and the cylinder movements are monitored by a transducer in the form of a linear differential voltage transformer to provide feedback signals. An accelerometer mounted on the pad provides a signal corresponding to the acceleration and de-acceleration of the pad. A threshold detector receiving the signal from the accelerometer controls an electronic switch to pass the accelerometer''s signal for use in controlling the shifting of the phase of the sine wave voltage when the amplitude of the accelerometer signal is equal to or greater than a predetermined amplitude. When the amplitude of the accelerometer''s signal is less than the predetermined amplitude, the threshold detector controls the electronic switch to pass the feedback signal corresponding to the cylinder movement to be used in shifting the phase of the sine wave voltage.
Inventors
👤 H Meyer
Bibliographic Details
Application Number—
JurisdictionUS
Data Sourcegoogle_patents
Last Synchronized2026-10-24 18:36
CPC Classifications
G; G01; G01V; G01V1/00; G01V1/02; G01V1/04
Claims Analysis
Total Claims: 2
Claim 1
Independent Claim
158 words
A method for inducing vibrations in an earth''s formation which comprises the following steps: providing a control signal of a variable frequency and phase, changing the frequency of the control signal in a predetermined manner, changing the phase of the control signal in accordance with a sum signal, sensing the movement of the pad and providIng a signal corresponding thereto, summing the movement signal with the control signal to provide the sum signal, sensing the acceleration and de-acceleration of the pad and providing a signal representative thereof, the improvement comprising shifting the phase of the movement signal so that the movement signal has substantially the same phase as the acceleration/deacceleration signal, providing the acceleration/de-acceleration signal as the phase correction signal when the amplitude of the acceleration/de-acceleration signal is equal to or greater than a predetermined amplitude; and providing the phase shifted movement signal as the phase correction signal when the acceleration/de-acceleration signal is less than the predetermined amplitude.
Claim 2
Independent Claim
158 words
A method for inducing vibrations in an earth''s formation which comprises the following steps: providing a control signal of a variable frequency and phase, changing the frequency of the control signal in a predetermined manner, changing the phase of the control signal in accordance with a sum signal, sensing the movement of the pad and providIng a signal corresponding thereto, summing the movement signal with the control signal to provide the sum signal, sensing the acceleration and de-acceleration of the pad and providing a signal representative thereof, the improvement comprising shifting the phase of the movement signal so that the movement signal has substantially the same phase as the acceleration/deacceleration signal, providing the acceleration/de-acceleration signal as the phase correction signal when the amplitude of the acceleration/de-acceleration signal is equal to or greater than a predetermined amplitude; and providing the phase shifted movement signal as the phase correction signal when the acceleration/de-acceleration signal is less than the predetermined amplitude.