An autonomous underwater seismic wave generation system includes a housing, and an autonomous navigation system, a propulsion system and a seismic wave generator, each connected to the housing. The autonomous navigation system can navigate the autonomous underwater seismic wave generation system to subsea locations including a location on a seabed. The propulsion system can drive the autonomous underwater seismic wave generation system to the location on the seabed. The seismic wave generator can couple to the location on the seabed to generate seismic waves at the location on the seabed.

Methods and systems for determining a spectral ratio log using a time domain seismic image and a seismic velocity model are disclosed. The method includes determining a first mono-spectral seismic image and a second mono-spectral seismic image from the time domain seismic image. The method further includes determining a time domain spectral ratio image from the first mono-spectral seismic image and the second mono-spectral seismic image and transforming the time domain spectral ratio image into a depth domain spectral ratio image using the seismic velocity model. The method still further includes defining a wellbore path through the depth domain spectral ratio image and determining a spectral ratio log along the wellbore path from the depth domain spectral ratio.

The present disclosure is directed to delivering nodes to an ocean bottom. A system can include a tether management system (TMS) towed by a vessel that moves on the surface of the ocean in a first direction. An underwater vehicle (UV) can be connected to the TMS and can move in a second direction that is different from the first direction. A thruster can be coupled to the TMS can cause the TMS to move in a third direction that is different from the first direction. A control unit can control the thruster to move the TMS in the third direction based on a cross-line location policy, and cause the UV to deploy nodes to target locations on the ocean bottom.

Systems and methods for improving or generating an image of a surveyed subsurface based on seismic interferometry. A method includes actuating interferometry-based sources over an area to be surveyed to generate seismic waves; recording seismic signals due to the interferometry-based sources, with seismic receivers; selecting traces corresponding to a pair of seismic receivers and an interferometry-based source such that ray paths between the interferometry-based source and the pair of seismic receivers contribute to a Green's function between the two receivers of the pair; cross-correlating the traces for calculating an earth's response associated with a ray propagating from a first seismic receiver of the pair to a second receiver of the pair; and generating an image based on the calculated earth's response.

Systems and methods for surveying a seafloor utilize two or more of seismic data, acoustic data and electrical potential or resistivity data to identify the locations of objects on or beneath the seafloor. The methods involve moving survey equipment over a geographic area of the seafloor and conducting a plurality of sensing or detecting operations while moving the survey equipment over the geographic area. The plurality of operations include two or more of: (1) a seismic operation that emits seismic energy toward the seafloor and collects seismic data based on seismic energy that returns from the seafloor, (2) an acoustic operation that emits acoustic energy toward the seafloor and collects acoustic data based on acoustic energy that returns from the seafloor, and/or (3) an electrical operation that supplies electrical power into seawater and that collects electric potential data indicative of electric potential that is induced into the seawater.

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.

A method and system for estimating a full elastic tensor. The method may comprise taking a measurement for compressional wave sonic data and cross-dipole shear data with a sonic logging tool at a first location as cross-dipole data, processing the compressional wave sonic data to produce a compressional wave slowness (P), and processing the cross-dipole shear data to produce a fast horizontal polarized shear wave slowness (SH) and a slow quazi-vertical shear wave slowness (qSV) as a function of depth. The method may further comprise setting an initial guess for at least five constants of the full elastic tensor for Vertical Transversely Isotropy (VTI) symmetry, determining a modeled slowness surfaces from the full elastic tensor, and comparing the modeled slowness surfaces with measured values of the P, the SH, and the qSV. The method may be performed by a system comprising a sonic logging tool and an information handling system.

A method for seismic surveying comprises deploying a plurality of seismic receivers proximate an area of subsurface to be surveyed. At least one seismic energy source moves in a path that circumscribes a center, wherein positions of the plurality of seismic receivers remain fixed. At least one of a distance between the path and the center changes monotonically as seismic energy source traverses the path, or the center moves in a selected direction as the seismic energy source traverses the path. The source is actuated at selected times as the at least one seismic energy source traverses the path, such that a spacing between positions of the source along the source path and transverse to the source path varies between successive actuations of the source. Seismic energy is detected at the plurality of seismic receivers resulting from actuating the at least one seismic energy source.

A method for seismic surveying comprises deploying a plurality of seismic receivers proximate an area of subsurface to be surveyed. At least one seismic energy source moves in a path that circumscribes a center, wherein positions of the plurality of seismic receivers remain fixed. At least one of a distance between the path and the center changes monotonically as seismic energy source traverses the path, or the center moves in a selected direction as the seismic energy source traverses the path. The source is actuated at selected times as the at least one seismic energy source traverses the path, such that a spacing between positions of the source along the source path and transverse to the source path varies between successive actuations of the source. Seismic energy is detected at the plurality of seismic receivers resulting from actuating the at least one seismic energy source.

Hybrid seismic inversion methods and apparatuses perform wave equation inversion and stochastic inversion to generate one or more final models for the reservoir characterization of the survey region. A method may include retrieving seismic data using seismic data recording sensors; storing the seismic data in the database; retrieving well data using the well born sensor in the wellbore; storing the seismic data in the database; storing geology integration information and one or more background models in the database; retrieving the seismic data and processing the seismic data to mitigate the seismic data for a seismic hybrid inversion; and performing the seismic hybrid inversion including performing wave equation inversion and stochastic inversion to generate the one or more final models for the reservoir characterization of the survey region.