Calibration apparatus including a pressure cap and a pressure base that define a pressure chamber that is fillable with a liquid. A reference sensor and a sensor under test are exposed to acoustic pressures in the liquid, and responses measured. The sensor under test is secured through one of the pressure cap or base, and responses measured at acoustic frequencies as low as 0.001 Hz and at hydrostatic pressures of at least 5000 psi.

Systems and methods for attenuating vibrations in marine seismic equipment involve a vessel towing a seismic streamer having a plurality of seismic receivers. The seismic streamer is connected to the vessel by a front-end and a damper is coupled to the front-end. A vibration on the front-end is detected and a damper response to the detected vibration on the front-end is then determined. The damper is actively adjusted based on the damper response. The active adjustment dampens vibrations in an axial direction along a lead-in of the front-end and/or vibrations in a direction transverse to an axial direction of the lead-in.

Systems and methods for attenuating vibrations in marine seismic equipment involve a vessel towing a seismic streamer having a plurality of seismic receivers. The seismic streamer is connected to the vessel by a front-end and a damper is coupled to the front-end. A vibration on the front-end is detected and a damper response to the detected vibration on the front-end is then determined. The damper is actively adjusted based on the damper response. The active adjustment dampens vibrations in an axial direction along a lead-in of the front-end and/or vibrations in a direction transverse to an axial direction of the lead-in.

A method for forming a sensing system responsive to a wavefield of acoustic or seismic signals. One embodiment includes providing a foil layer having first and second opposing surfaces and piezoelectric properties. The foil layer, configured as a sheet, is positioned about a frame surface which provides the foil layer a stable shape while permitting the sheet configuration of the foil layer to be responsive to a wavefield of seismic or acoustic energy. Coupling between the foil layer and the frame is so limited as to render direct coupling of the foil layer with signals of the wavefield the predominant means for stimulating the sensor element with seismic energy.

A method for forming a sensing system responsive to a wavefield of acoustic or seismic signals. One embodiment includes providing a foil layer having first and second opposing surfaces and piezoelectric properties. The foil layer, configured as a sheet, is positioned about a frame surface which provides the foil layer a stable shape while permitting the sheet configuration of the foil layer to be responsive to a wavefield of seismic or acoustic energy. Coupling between the foil layer and the frame is so limited as to render direct coupling of the foil layer with signals of the wavefield the predominant means for stimulating the sensor element with seismic energy.

Embodiments relate to marine streamer cleaning. An embodiment provides a streamer cleaning apparatus comprising: a housing comprising an inlet configured to receive a streamer and an outlet configured to dispatch the streamer; and scraper lamellas coupled to the housing, wherein the scraper lamellas are arranged to form an opening to receive the streamer. Methods of cleaning a streamer and streamer cleaning systems are also provided.

Embodiments relate to marine streamer cleaning. An embodiment provides a streamer cleaning apparatus comprising: a housing comprising an inlet configured to receive a streamer and an outlet configured to dispatch the streamer; and scraper lamellas coupled to the housing, wherein the scraper lamellas are arranged to form an opening to receive the streamer. Methods of cleaning a streamer and streamer cleaning systems are also provided.

A metal detector with multiple detection zones of alternating polarity achieved by means of multiple coil windings such that when a target moves across it, a detection signal of alternating polarity is generated with a waveform shape which replicates the pattern of zones, a distinctive detection waveform which enables enhanced recognition of target presence while in motion. Balance to external EMI enables the use of large coils for non-swinging searching at high area searching rates.

To store sensor devices in a sensor storage system, the sensor devices are hanged on hangers in the sensor storage system. The sensor devices are transported through stations of the sensor storage system.

A proximity sensor includes a lead supported on an outer surface of a case structure and a sensor wire that extends from the lead and through an opening in the case structure. The sensor is formed by applying alternating layers of electrically conductive and non-conductive materials in a non-cured state. A base non-conductive layer is applied to an inner surface of the case structure around the sensor wire in a non-cured state. Once cured, a conductive layer is deposited onto the base non-conductive layer and encapsulates the sensor wire. A cover non-conductive layer is then deposited over portions of the conductive layer to insulate the conductive layer. Portions of the non-conductive layer are then removed such that an area of the conductive layer is exposed to define a sensor area.