Electromagnetic linear actuators for marine acoustic vibratory sources
AssigneePGS Geophysical AS
InventorSven Göran Engdahl
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Abstract
Disclosed are electromagnetic linear actuators used in acoustic vibratory sources for marine seismic surveying. An embodiment discloses a linear actuator for acoustic sources, comprising: magnetic circuitry comprising a gap; and a coil assembly comprising: a drive coil, wherein at least a first portion of the drive coil is configured to be moved in a linear path in the gap; a pair of ferromagnetic coil guides positioned on either side of the linear path; a first ferromagnetic extension extending laterally from the first portion of the drive coil; and a transmission element coupled to a top side of the first portion of the drive coil. Embodiments also disclose acoustic vibratory sources, marine seismic survey systems, and methods of marine seismic surveying.
Claims29
A linear actuator for acoustic sources, comprising:
- magnetic circuitry comprising a first gap;
- and
- a first coil assembly comprising:
- a drive coil, wherein at least a first portion of the drive coil is configured to be moved in a linear path in the first gap;
- a pair of ferromagnetic coil guides positioned on either side of the linear path;
- a first ferromagnetic extension extending laterally from the first portion of the drive coil;
- and
- a transmission element coupled to a top side of the first portion of the first drive coil.
An acoustic vibratory source, comprising:
- a flextensional shell defining a longer axis and a shorter axis;
- and
- a linear actuator coupled to the flextensional shell proximate an end of the shorter axis, wherein the linear actuator comprises:
- magnetic circuitry comprising gaps;
- a pair of opposing coil assemblies, wherein the coil assemblies each comprise:
- a drive coil, wherein at least a portion of each of the drive coils is configured to be moved in a linear path in at least one of the gaps in the magnetic circuitry;
- a first ferromagnetic extension extending laterally from the drive coil;
- and
- a transmission element coupled to the drive coil.
A marine seismic survey system, comprising:
- a vessel;
- an acoustic vibratory source coupled to the vessel, wherein the acoustic vibratory source comprises:
- a flextensional shell defining a longer axis and a shorter axis;
- and
- a linear actuator coupled to the flextensional shell proximate an end of the shorter axis, wherein the linear actuator comprises:
- magnetic circuitry comprising gaps;
- a pair of opposing coil assemblies, wherein the coil assemblies each comprise:
- a drive coil, wherein at least a portion of the drive coil is configured to be moved in a linear path in at least one of the gaps in the magnetic circuitry;
- a first ferromagnetic extension extending laterally from the drive coil;
- and
- a transmission element coupled to the drive coil;
- and
- an electrical controller capable of actuating the linear actuator.
The marine seismic survey system of 18, wherein the acoustic vibratory source is configured to have a resonance frequency of below about 10 Hz when disposed in the water.
The marine seismic survey system of 18, wherein each of the coil assemblies comprises a second ferromagnetic extension extending laterally from the drive coil opposite the first ferromagnetic extension.
The marine seismic survey system of 18, wherein the first ferromagnetic extension for each drive coil is integral with the corresponding drive coil, wherein the drive coil for each of the coil assemblies comprises a ferromagnetic material.
A method of marine seismic surveying, comprising:
- towing a seismic sensor streamer with a vessel through a body of water over a subterranean formation;
- controlling a first acoustic vibratory source to generate a first seismic signal, wherein the first acoustic vibratory source comprises:
- a flextensional shell defining a longer axis and a shorter axis;
- and
- a linear actuator coupled to the flextensional shell proximate an end of the shorter axis, wherein the linear actuator comprises:
- magnetic circuitry comprising gaps;
- a pair of opposing coil assemblies, wherein the coil assemblies each comprise:
- a drive coil, wherein at least a portion of the drive coil is configured to be moved in a linear path in at least one of the gaps in the magnetic circuitry;
- a first ferromagnetic extension extending laterally from the drive coil;
- and
- a transmission element coupled to the drive coil;
- allowing the first seismic signal to propagate through the body of water and the subterranean formation to provide a first modified seismic signal;
- and
- detecting the first modified seismic signal with the seismic sensor streamer.
Dependencies are inferred from the claim text.