The invention relates to an arrangement for seismic acquisition the spacing between each adjacent pairs of receiver and sources lines is not all the same. Some receiver and/or source lines and/or receiver and/or source spacings are larger and some are smaller to provide a higher quality wavefield reconstruction when covering a larger total area or for a similar total area of seismic data acquisition while providing a wavefield that is optimally sampled by the receivers and sources so that the wavefield reconstruction is suitable for subsurface imaging needs.

The invention relates to an arrangement for seismic acquisition the spacing between each adjacent pairs of receiver and sources lines is not all the same. Some receiver and/or source lines and/or receiver and/or source spacings are larger and some are smaller to provide a higher quality wavefield reconstruction when covering a larger total area or for a similar total area of seismic data acquisition while providing a wavefield that is optimally sampled by the receivers and sources so that the wavefield reconstruction is suitable for subsurface imaging needs.

A technique facilitates monitoring of acoustic signals to measure a velocity vector of a borehole. Acoustic sensors are arranged in a desired acoustic sensor array and positioned along a body of a tool, e.g. a sonic logging tool. The acoustic sensor array is then positioned in fluid along a wall of a borehole formed in a subterranean formation. The acoustic sensors are used to collect acoustic signal data while the acoustic sensors are maintained in a non-contact position with respect to the wall of the borehole. The data may be processed to determine the desired velocity vector.

Methods, systems, and apparatuses are disclosed for sensing acoustic waves in a medium. One example system includes a first elongated member, a first motion sensor sensitive to vibrations of the first elongated member, a second motion sensor spaced apart from the first motion sensor and also sensitive to vibrations of the first elongated member, and a first vibration source operably coupled to the first elongated member and configured to vibrate the first elongated member.

Methods, systems, and apparatuses are disclosed for sensing acoustic waves in a medium. One example system includes a first elongated member, a first motion sensor sensitive to vibrations of the first elongated member, a second motion sensor spaced apart from the first motion sensor and also sensitive to vibrations of the first elongated member, and a first vibration source operably coupled to the first elongated member and configured to vibrate the first elongated member.

Presented are methods and systems for collecting marine seismic data. The collected seismic data can be low frequency (e.g., less than 10 Hz) or it can be a full seismic bandwidth (1-200 Hz) depending on if the low frequency tuned sources and tuned receivers are combined with conventional sources and receivers. The low frequency sources can be towed or they can be autonomous and positioned in the survey area by tether, drifting or self-propelled. The tuned low frequency receivers are towed at a depth greater than conventional receivers and the sources can be fired independently or simultaneously.

Methods for determining sensor channel location in distributed sensing of fiber-optic cables are disclosed. In one method, three or more Fiber Bragg-Gratings (FBGs) connected in series by a standard telecommunication fiber and interrogated using an input distributed fiber-optic sensing (DFOS) laser, where the input DFOS laser has a single wavelength. The input DFOS laser operates on a single wavelength that is different than the respective wavelengths of each of the three or more FBGs. The three or more FBGs are interrogated using an input broadband FBG laser. Each FBG reflects a wavelength of laser light that is proportional to the grating size, using an optical time domain reflectometer (OTDR) at the FBG wavelength, the distance to the particular FBG in the optical domain is computed and compared to the physical measurement of the FBG location. The sensor channel locations of the DFOS system are calibrated and constrained using this method.

Seismic node systems can be configured for acquiring seismic sensor data with an array of seismic receivers or nodes deployable in a survey area, each receiver or node having a seismic sensor for acquiring the seismic sensor data, a clock, a controller and local memory. The seismic sensor can data characterize a seismic wavefield proximate the seismic receivers in the survey area. Quality control data can be generated based on the seismic sensor data and associated timing information provided by the respective clock, and incorporated into a seismic data flow for recording in the local memory.

A seismic deployment system having a deployment apparatus, a tow line, and a carrier line having a plurality of seismic sensor coupled therealong. The deployment apparatus has a hydrodynamic body. The tow line is configured for towing the hydrodynamic body through a water column. The carrier line is engaged with the deployment apparatus. The deployment apparatus is configured to control tension in the carrier line for deployment of the seismic sensors while the hydrodynamic body is towed through the water column by the tow line.

The present invention provides a marine cable device configured for preventing or reducing biofouling along its exterior surface, which during use is at least temporarily exposed to water. The marine cable device according to the present invention comprises at least one light source configured to generate an anti-fouling light and at least one optical medium configured to receive at least part of the anti-fouling light. The optical medium comprises at least one emission surface configured to provide at least part of said anti-fouling light on at least part of said exterior surface.