摘要:
Embodiments related to restriction of gas flow in a marine acoustic vibrator to compensate for gas spring effects. An embodiment provides a marine acoustic vibrator, comprising: an outer shell; and a variable gas flow restrictor disposed within the outer shell; wherein the marine acoustic vibrator has a resonance frequency selectable based at least in part on the variable gas flow restrictor.
摘要:
Systems, sensors, and methods for high-speed image monitoring of baseplate movement in a vibrator. The systems can include a baseplate defined by an area, disposable at a ground surface to direct a seismic force into the ground surface. The system can include a reaction mass coupled to and positioned above the baseplate to generate the seismic force at the baseplate. The system can include an actuator assembly coupled to the reaction mass to vibrate the reaction mass, as well as high-speed image units directed at the area of the baseplate. The high-speed image units can include photo detectors to sense a distribution of acceleration across the area of the baseplate, and a light source emit light to be sensed by the photo detectors. The system can also include a controller coupled to the actuator assembly, that drives the actuator assembly.
摘要:
A resonant source element configured to generate seismic waves. The resonant source element includes a housing; a high-pressure system configured to be discharged inside the housing; and a first conduit attached to an opening of the housing, wherein a distal end of the first conduit freely communicates with an ambient.
摘要:
A resonant source element is configured to generate seismic waves in water. The resonant source element includes a housing having two openings covered by first and second pistons, wherein the first and second pistons are configured to freely translate relative to the housing to generate the seismic waves; and a high-pressure system configured to discharge inside the housing and to actuate the first and second pistons. The first and second pistons are configured to oscillate after the high-pressure system is fired to generate low-frequency seismic waves.
摘要:
Method, source array and source element that generate seismic waves. The source element includes an enclosure having an opening covered by a piston; a local supply accumulator fluidly communicating with an interior of the enclosure, a pressure of the fluid inside the local supply accumulator being larger than a pressure of the fluid inside the enclosure; a local supply valve located between the local supply accumulator and the enclosure and configured to control a flow of the fluid from the local supply accumulator to the interior of the enclosure; and a controller configured to control the local supply valve such that the pressure inside the enclosure does not fall below a first preset value based upon an ambient pressure of the enclosure while seismic waves are generated.
摘要:
A seismic vibrator includes a baseplate having a surface configured to couple to a ground surface. A driver is coupled to the baseplate and is configured to move the baseplate in a vibratory manner. A decoupling system is coupled to a part of the baseplate other than the ground-contacting surface. The decoupling system includes a first layer having a Young's modulus greater than that of a second layer coupled to the first layer. The second layer is coupled to the baseplate. The Young's moduli, thicknesses and masses of the first and second layer are selected to provide the decoupling system with a resonant frequency of at most, a spatial aliasing frequency of seismic sensors deployed on the ground surface or a lowest seismic frequency of interest.
摘要:
A low frequency sound source has a radiating piston (3) of the order of a few meters across backed by a gas spring (13, 15) containing a fixed mass of gas. The gas pressure in the spring is kept at levels for which the natural frequency of the piston (3) loaded by the fluid (41) lies in the seismic band and may be as low as 0.5 Hz. The piston (3) is given an initial displacement and begins to oscillate. Its oscillations are sustained by an actuator (27, 29) whose drive signal is derived from the velocity of the piston (5) via a velocity or displacement sensor. The sound source is caused to perform a frequency sweep by gradually compressing the gas in the gas spring (13, 15) so that the spring becomes stiffer both because of the rising pressure and because of the reducing length of the gas spring spaces (13, 15). This double effect allows large changes in stiffness to be produced and hence allows the source to operate over at least three octaves of frequency.
摘要:
A seismic source configured to generate seismic waves underground. The source includes a tank configured to be buried underground, the tank having a cavity; an actuation mechanism provided inside the cavity, wherein the actuation mechanism is configured to have at least one movable part that moves back and forth to generate a seismic wave having a desired frequency; and a first fluid provided inside the cavity and around the actuation mechanism and configured to transform the back and forth movement of the at least one movable part into a varying pressure that directly acts on walls of the tank.
摘要:
The invention is an apparatus for generating a seismic signal in a fluid filled borehole which includes an elongated housing formed from a gas impermeable material and a controlled frequency energy source within said housing. The housing has an external shape which expands and contracts in response to variations in pressure within said housing to enhance the transmission of said seismic signal to the borehole fluid, such as pressure variations resulting from fluid resonance within said housing.
摘要:
A seismic acoustic signal source includes a hull that has a wetted surface in contact with a body of water. When underway, the draft of the hull is substantially zero. An acoustic signal generator is provided with a linear actuator that is resiliently mounted in the hull. The linear actuator is acoustically coupled to the hull bottom such that when the signal generator is activated, the hull radiates an acoustic wavefield into the water.