A compact seismic source for seismic acquisition generating a humming signal includes a casing and a low-frequency reciprocating drive. The casing defines a fluid tight chamber and comprises a first casing section and a second casing section of roughly equal mass. The drive is disposed within the fluid tight chamber and, in operation, reinforces the natural reciprocating oscillation of the first and second casing sections relative to one another at a low seismic frequency. In one aspect, this action omni-directionally radiates the low frequency, humming seismic signal. On another aspect, the compact seismic source is substantially smaller than the wavelength of the low seismic frequency. Such a compact source may be deployed to omni-directionally radiate a low frequency, humming seismic signal during a seismic survey.

A compact seismic source for seismic acquisition generating a humming signal includes a casing and a low-frequency reciprocating drive. The casing defines a fluid tight chamber and comprises a first casing section and a second casing section of roughly equal mass. The drive is disposed within the fluid tight chamber and, in operation, reinforces the natural reciprocating oscillation of the first and second casing sections relative to one another at a low seismic frequency. In one aspect, this action omni-directionally radiates the low frequency, humming seismic signal. On another aspect, the compact seismic source is substantially smaller than the wavelength of the low seismic frequency. Such a compact source may be deployed to omni-directionally radiate a low frequency, humming seismic signal during a seismic survey.

A submersible sound system may include a housing, an end piece, an elastic membrane, an end cap affixed to the elastic membrane, and a subwoofer speaker system disposed within the housing and supported by a speaker support. A bubble sound source may be defined by the speaker support, the speaker diaphragm, an anterior end of the housing, the elastic membrane, and the end cap. The housing, end piece, and a posterior surface of the speaker support may form a sealed enclosure. The sound system may include a tuning pipe disposed between the sealed enclosure and the bubble sound source. A Helmholtz resonator may be disposed anteriorly of the speaker system. Multiple sound system may be assembled to form a cluster. The cluster may be defined by the vertices of regular polyhedron. The sound systems may be controlled to maintain the speaker systems within acceptable thermal limits.

An improved servovalve for a seismic vibrator or vibration machine which includes a left additional passageway conducting a portion of sampled pressure from a left cylinder pressure chamber to only a portion of the right end drive surface of the spool, wherein the portion of the right end drive surface is less that of the entirety of the right end drive surface; and a right additional passageway conducting a portion of sampled pressure from a right cylinder pressure chamber to only a portion of the left end drive surface of the spool, wherein the portion of the left end drive surface is less that the entirety of the left end drive surface; thereby providing at least two additional passageways configured to provide linear proportional pressure feedback in spool movement control.

A submersible sound system may include a housing, an end piece, an elastic membrane, an end cap affixed to the elastic membrane, and a subwoofer speaker system disposed within the housing and supported by a speaker support. A bubble sound source may be defined by the speaker support, the speaker diaphragm, an anterior end of the housing, the elastic membrane, and the end cap. The housing, end piece, and a posterior surface of the speaker support may form a sealed enclosure. The sound system may include a tuning pipe disposed between the sealed enclosure and the bubble sound source. A Helmholtz resonator may be disposed anteriorly of the speaker system. Multiple sound system may be assembled to form a cluster. The cluster may be defined by the vertices of regular polyhedron. The sound systems may be controlled to maintain the speaker systems within acceptable thermal limits.

A submersible sound system may include a housing, an end piece, an elastic membrane, an end cap affixed to the elastic membrane, and a subwoofer speaker system disposed within the housing and supported by a speaker support. A bubble sound source may be defined by the speaker support, the speaker diaphragm, an anterior end of the housing, the elastic membrane, and the end cap. The housing, end piece, and a posterior surface of the speaker support may form a sealed enclosure. The sound system may include a tuning pipe disposed between the sealed enclosure and the bubble sound source. A Helmholtz resonator may be disposed anteriorly of the speaker system. Multiple sound system may be assembled to form a cluster. The cluster may be defined by the vertices of regular polyhedron. The sound systems may be controlled to maintain the speaker systems within acceptable thermal limits.

A seismic vibrator is configured to operate close to resonance for range of actuating frequencies. The vibrator has a baseplate, a reaction mass coupled to the baseplate via an elastic coupling mechanism and an actuator configured to displace the reaction mass with an actuating frequency. The vibrator also has a frequency-adjusting system configured to adjust a natural frequency of the elastic coupling mechanism and the reaction mass, to track the actuating frequency so that to achieve resonance.

A seismic vibrator is configured to operate close to resonance for range of actuating frequencies. The vibrator has a baseplate, a reaction mass coupled to the baseplate via an elastic coupling mechanism and an actuator configured to displace the reaction mass with an actuating frequency. The vibrator also has a frequency-adjusting system configured to adjust a natural frequency of the elastic coupling mechanism and the reaction mass, to track the actuating frequency so that to achieve resonance.

The invention discloses a monitoring system for deformations and destructions of a gas storage, including an acoustic emission sensor installed in a borehole of a monitored rock mass and a ground workstation. The acoustic emission sensor includes an acoustic emission probe and a probe installation mechanism for installing the acoustic emission probe and a transmission mechanism for transmitting the probe installation mechanism. The probe installation mechanism includes a shell, a probe sleeve and two sets of pistons hydro-cylinder components. The present invention realizes the control of the moving direction of the shell and the probe sleeve by the piston hydro-cylinder component and the hydraulic pump, thus solving the problem of effective installation and coupling of the acoustic emission probe, ensuring the effective coupling between the acoustic emission probe and the wall of the borehole.

The invention discloses a monitoring system for deformations and destructions of a gas storage, including an acoustic emission sensor installed in a borehole of a monitored rock mass and a ground workstation. The acoustic emission sensor includes an acoustic emission probe and a probe installation mechanism for installing the acoustic emission probe and a transmission mechanism for transmitting the probe installation mechanism. The probe installation mechanism includes a shell, a probe sleeve and two sets of pistons hydro-cylinder components. The present invention realizes the control of the moving direction of the shell and the probe sleeve by the piston hydro-cylinder component and the hydraulic pump, thus solving the problem of effective installation and coupling of the acoustic emission probe, ensuring the effective coupling between the acoustic emission probe and the wall of the borehole.