Abstract: Inversion of enhanced-sensitivity controlled source electromagnetic data can include combining measured controlled source electromagnetic (CSEM) data onto a common set of virtual receiver positions for each of a plurality of positions of a source along a survey path, determining a steering vector that enhances a sensitivity of the measured CSEM data to a subsurface resistivity variation, and performing an inversion using the measured CSEM data and modeled CSEM data, each having the steering vector applied thereto as a data weight, to better identify the subsurface resistivity variation.

Abstract: A method for seismic data processing can include obtaining seismic data acquired based upon trigger times and not based upon positions of triggered source elements. The seismic data can include near-continuously recorded seismic data in split records. The split records can be spliced together into a single near-continuous record to produce a trace with seismic data from a single acquired line. The seismic data can be processed by performing a spatial shift for each of a number of time samples to correct for motion of a number of seismic receivers.

Abstract: Techniques are disclosed relating to geophysical surveying and data processing using streamers at different depths. In one embodiment, a method includes obtaining geophysical data specific to a geophysical formation that includes a first set of data representative of a first particle motion signal and a first pressure signal recorded using sensors at a first depth and a second set of data representative of a second particle motion signal and a second pressure signal recorded using sensors at a second, greater depth. In this embodiment, the method includes generating first and second wave separation equations from the first and second sets of data and determining a cross-line wavenumber value that reconciles the first and second equations. The determined cross-line wavenumber may be used to separate measured up-going and down-going wavefields.

Abstract: This disclosure describes processes and systems for generating a seismic image of a subterranean formation from recorded seismic data gathers obtained in a marine seismic survey of the subterranean formation. The seismic data comprises recorded pressure and vertical velocity wavefields that are used to separate the recorded pressure wavefield into upgoing and downgoing pressure wavefields. A seismic image is computed from the subterranean formation based on a product of the downgoing pressure wavefield and a migration operator applied to the upgoing pressure wavefield. The downgoing pressure wavefield is a boundary source wavefield and the upgoing pressure wavefield is boundary receiver wavefield of the migration operator. The seismic image is iteratively updated by computing a residual seismic image based on the upgoing pressure wavefield and adding the residual seismic image to the seismic image.

Abstract: Techniques are disclosed relating to reducing noise in geophysical marine survey data. Such techniques may include adapting an initial set of noise templates to recorded seismic data to generate adapted noise templates and estimating a noise component in the recorded seismic data. The estimating may include determining a degree to which noise and signal components are correlated in the recorded seismic data and masking the recorded seismic data proportionally to the degree of correlation. The adapted noise templates may then be further adapted to a difference between the estimate of the noise component and the noise templates themselves. Resultant noise templates may then be applied to denoise the recorded seismic data.

Abstract: Disclosed are advantageous designs for highly-sparse seabed acquisition for imaging geological structure and/or monitoring reservoir production using sea surface reflections. The highly-sparse geometry designs may be adapted for imaging techniques using the primary and higher orders of sea surface reflection and may advantageously allow for the use of significantly fewer sensors than conventional seabed acquisition. The highly-sparse geometry designs may be relevant to 3D imaging, as well as 4D (“time-lapse”) imaging (where the fourth dimension is time). In accordance with embodiments of the invention, geophysical sensors may be arranged on a seabed to form an array of cells. Each cell in the array may have an interior region that contains no geophysical sensors and may be sufficiently large in area such that a 500 meter diameter circle may be inscribed therein.

Abstract: A seismic streamer includes an outer sheath that forms an interior region of the seismic streamer of which a portion is filled with a gel or liquid. The streamer also includes at least one stress member placed off-center in the interior region, and multiple sensors mounted proximate to a center of the interior region, where the sensors include a pressure sensor and a motion sensor. The streamer further includes multiple tilt sensors mounted along the interior region. A method of manufacturing a seismic streamer includes placing at least one stress member off-center along a first direction, mounting multiple spacers along the stress member, and affixing sensors to respective spacers, where the sensors include a pressure sensor and a motion sensor. The method further includes mounting tilt sensors along the first direction and affixing an outer sheath to the streamer that forms an interior region of the seismic streamer.

Abstract: Deploying and retrieving streamer cleaning devices. At least some of the example embodiments are methods including transferring a streamer cleaning device to a geophysical sensor streamer. The transferring may include towing the geophysical sensor streamer through water while the geophysical sensor streamer submerged, towing a tow fish through water by way of an umbilical (the streamer cleaning device coupled within a payload area of the tow fish during the towing of the tow fish through the water), landing the tow fish on the geophysical sensor streamer and thereby abutting the streamer cleaning device against the geophysical sensor streamer, closing the streamer cleaning device around the geophysical sensor streamer, releasing the streamer cleaning device from the payload area, and separating the tow fish from streamer cleaning device and the geophysical sensor streamer.

Abstract: Inversion of enhanced-sensitivity controlled source electromagnetic data can include approximating a background response from measured controlled source electromagnetic (CSEM) response data. The approximation can include performing a first inversion of the CSEM response data using a largest singular value in a diagonal of a matrix associated with the CSEM response data to create a first resistivity model of a subsurface of a subterranean formation and iteratively performing subsequent inversions while increasing an amount of singular values in the diagonal to obtain modeled CSEM response data to create a second resistivity model of the subsurface of the subterranean formation. Inversion of enhanced-sensitivity controlled source electromagnetic data can further include storing results of the first inversion and the iterative subsequent inversions producing a resistivity map based on the first and the second resistivity models.

Abstract: A system for bridle bite adjustment can include a tow rope coupled to a paravane at a first position on a lever arm and a spur line coupled to the paravane at a second position on the lever arm. The system can also include a winch to adjust a deployed length of the tow rope. The tow rope and the lever arm can adjust a bridle bite of the paravane by when the deployed length of the tow rope is adjusted by the winch, thereby balancing tension between the tow rope and the spur line.

Abstract: Embodiments relate generally to marine geophysical surveying. More particularly, embodiments relate to an underwater application system for application of a streamer coating to a surface of a streamer. An embodiment may comprise a marine geophysical survey system. The marine geophysical survey system may comprise a streamer and an underwater application system operable to apply a streamer coating to the streamer as the underwater application system travels axially along the streamer.

Abstract: Marine survey data can be acquired at a tow line. The tow line is designed to be coupled between a marine survey vessel and a towed object. A receiver is associated with the tow line and designed to receive marine survey data at a location of the tow line. The receiver can be an optical fiber or other type of receiver.

Abstract: Methods and systems for generating an image of a subterranean formation from recorded seismic data obtained in a marine seismic survey of a subterranean formation are described. Methods and systems compute a volume of migrated seismic data obtained from the recorded seismic data. Spectrally enhanced traces of the migrated seismic data are computed in overlapping windows of the volume of migrated seismic data. The spectrally enhanced traces of the volume of migrated seismic data are used to generate a spectrally enhanced image of the subterranean formation.

Abstract: Roll data can be acquired from a magnetometer and an accelerometer of a towed object telemetry unit coupled to a towed object during rolls of the towed object in two or more different headings. The magnetometer can be calibrated based on the roll data. Turn data can be acquired from the magnetometer and the accelerometer during a turn of the towed object from a first heading to a second heading. The magnetometer can be further calibrated based on the turn data.

Abstract: Apparatus and methods are disclosed relating to a body towable behind a vessel in a body of water, an arm rotatably coupled to the body, and one or more foils disposed on the arm. The arm, when deployed, is configured to be free to rotate as the apparatus is towed through the body of water. The one or more foils are configured to generate lift as the apparatus is towed. Due to the free rotation of the arm, the foils impart tension force to the body and not torque forces.

Abstract: An apparatus can include a base assembly and a pivot assembly coupled to the base assembly. The apparatus can include a carriage coupled to the pivot assembly. The carriage can be shaped to receive a compass streamer telemetry unit (CSTU). The carriage can be configured to secure the CSTU. The pivot assembly can be rotatably coupled to the base assembly to adjust a pitch of the carriage. The carriage can be rotatably coupled to the pivot assembly to adjust roll of the carriage.

Abstract: Disclosed are advantageous designs for highly-sparse seabed acquisition for imaging geological structure and/or monitoring reservoir production using sea surface reflections. The highly-sparse geometry designs may be adapted for imaging techniques using the primary and higher orders of sea surface reflection and may advantageously allow for the use of significantly fewer sensors than conventional seabed acquisition. The highly-sparse geometry designs may be relevant to 3D imaging, as well as 4D (“time-lapse”) imaging (where the fourth dimension is time). In accordance with embodiments of the invention, geophysical sensors may be arranged on a seabed to form an array of cells. Each cell in the array may have an interior region that contains no geophysical sensors and may be sufficiently large in area such that a 500 meter diameter circle may be inscribed therein.

Abstract: Seismic data are obtained by recording simultaneously in seismic streamer, acquired by activating approximately simultaneously two or more seismic sources towed at two positions in the vicinity of seismic streamers. A residual is updated iteratively for an inversion solution for the activations of the two or more seismic sources. The iterative updating of the residuals utilizes a sequence of overlapping temporal windows containing reflection events and utilizes normal moveout corrections based on largest reflection events in each temporal window. A final updated residual is added to a final updated model result.

Abstract: Inversion for marine seismic imaging of a full reflected wavefield can include generating an image of a subsurface formation by full wavefield migrating a recorded seismic wavefield and generating numerically modeled data using the image. A mismatch between the numerically modeled data and the seismic wavefield can be determined. Responsive to determining that the mismatch exceeds an inversion match threshold, the image can be updated using the mismatch between the numerically modeled data and the seismic wavefield.

Abstract: Parameters of a sweep signal that controls operation of a marine non-impulsive source can be set. Setting the parameters can include selecting a stop frequency of the sweep signal, defining a taper of the sweep signal, and adjusting an initial phase of the sweep signal. The parameters can be set such that a magnitude of an amplitude spectrum of a combined output of a marine impulsive source and the marine non-impulsive source is greater than or equal to a magnitude of an amplitude spectrum of a marine impulsive source output at frequencies below the stop frequency. A controller of the marine non-impulsive source can be programmed with the sweep signal having the parameters set to control the marine non-impulsive source.