Abstract: One or more images of subsurface geological features are generated based on recorded seismic data that contain controlled source components and uncontrolled source components blended together. A current recorded dataset is determined from the recorded seismic data, and one or more iterations of a separation procedure are performed on the current recorded dataset to accumulate isolated controlled source components and isolated uncontrolled source components therefrom. The one or more images are generated based on the isolated controlled source components and on the isolated uncontrolled source components.

Abstract: Techniques are disclosed relating to machine learning in the context of noise filters for sensor data, e.g., as produced by geophysical surveys. In some embodiments, one or more filters are applied to sensor data, such a harsh filter determined to cause a threshold level of distortion in measured reflections, a mild filter determined to leave a threshold level of remaining noise signals, or an acceptable filter. In some embodiments, the system trains a machine learning classifier based on outputs of the filtering procedures and uses the classifier to determine whether other filtered sensor data from the same survey exhibits acceptable filtering. This may improve accuracy or performance in detecting unacceptable filtering, in some embodiments.

Abstract: A vessel is configured to tow a marine seismic source, a spread of standard-offset streamers, and a long-offset streamer in a manner such that: a standard streamer maximum offset, measured from the at least one source to an aft-most receiver in the standard-offset streamers, is not more than 20 km; and a long-offset streamer maximum offset, measured between the at least one source and an aft-most receiver in the long-offset streamer, is longer than the standard streamer maximum offset and is between 12 km and 40 km. In some embodiments, the long-offset streamer and the standard-offset streamers are coupled to a same spreader line. In other embodiments, the long-offset streamer is coupled to the vessel by a long-offset lead-in line. In still other embodiments, the standard-offset streamers are coupled to a first spreader line, and the long-offset streamer is coupled to a second spreader line disposed aft of the first spreader line.

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: Methods and apparatus are described for performing a 4D monitor marine seismic survey that repeats a previous survey. A number of sources may be used during the 4D monitor survey that differs from a number of sources that were used during the previous survey. Shot points from the previous survey are repeated by the 4D monitor survey, and additional shot points may be produced during the 4D monitor survey that were not produced during the previous survey. Embodiments enable efficiency and data quality improvements to be captured during 4D survey processes, while preserving repeatability.

Abstract: A system and method controls impulsive source activations in a blended acquisition marine seismic survey. A component of the system generates a sequence of dither values deterministically and stores the sequence of dither values, or source activation indicators derived therefrom, in a non-transitory medium readable by a control system operable to execute shot points during the survey responsive to the values stored in the medium. According to some embodiments, generating the dither values comprises iteratively selecting from a fixed set of candidate dither values to produce a candidate sequence of dither values. The selecting is based on evaluating one or more quantitative measures of randomness and one or more quantitative measures of separation exhibited by at least a portion of the candidate sequence of dither values. Generated sequences improve deblending results by reducing coherence exhibited by the dither values in the sequences.

Abstract: A method and apparatus for marine surveying includes: towing sources in a wide-tow source geometry; towing streamers that comprise receivers; actuating at least one of the sources to create a signal; and detecting the signal with a first receiver, wherein: at least one of the source separations or the streamer separations is non-uniform, and the sources and the receivers provide a regular sampling grid for the survey area. A system includes a survey plan; sources in a wide-tow source geometry; and streamers comprising receivers, wherein: at least one of the source separations or the streamer separations is non-uniform, and the sail lines, sources, and receivers provide uniform CMP coverage for the survey area. A method includes operating a system in a survey area, the system having a non-uniform configuration with wide-tow source geometry; actuating at least one source to create a signal; and detecting the signal with a first receiver.

Abstract: A long-offset acquisition system includes a source vessel; a signal source coupled to the source vessel; and a long-offset streamer coupled to a survey vessel and including an aft-most receiver, an offset of the aft-most receiver being at least 12 km. A long-offset acquisition method includes towing a signal source with a source vessel; towing a first long-offset streamer with a survey vessel; and acquiring data with receivers of the first long-offset streamer. A long-offset acquisition method includes towing a signal source with a first survey vessel; towing a long-offset streamer with a second survey vessel, the long-offset streamer having a plurality of receivers; actuating the signal source while an offset between the signal source and at least one of the plurality of receivers is at least 15 km; and acquiring data with receivers of the long-offset streamer.

Abstract: A marine streamer includes: an optical fiber disposed along a length of the streamer; a light source; and light analysis equipment, wherein: the length is at least 20 km, a diameter of the streamer is no more than 25 mm, the optical fiber, light source, and light analysis equipment are configured to provide a receiver sampling density of at least 1 per meter, and the streamer is configured to be towed nominally horizontally through a body of water. A method of marine surveying includes: towing a streamer spread at a first depth of 10 m to 30 m with a survey vessel; and towing Distributed Acoustic Sensing (DAS) streamers at a second depth of greater than 30 m. A method includes: acquiring long-offset data with sensors distributed along the DAS streamers.

Abstract: Methods and apparatus are described for reducing noise in measurements made by one or more pressure sensors disposed in a cable having a generally longitudinal axis. Estimated axial vibration noise at a location along the cable is determined based at least in part on measurements from one or more motion sensors disposed along the cable. The estimated axial vibration noise is subtracted from pressure sensor measurements corresponding to the location. The result is noise-attenuated pressure sensor measurements corresponding to the location.

Abstract: One or more first sensors may be configured to sense seismic signals and one or more second sensors may be configured to sense electromagnetic crosstalk signals. The second sensors are not responsive to the seismic signals. The data from the first and second sensors may be recorded as first data and second data, respectively. The first data may be modified based on the second data to remove the electromagnetic crosstalk noise form the seismic data.

Abstract: Methods and systems described herein are directed to determining properties of a subterranean formation using an acoustic wave-equation in terms of a velocity model and a vector reflectivity model of the subterranean formation. The acoustic wave equation may be used with simultaneous inversion to simultaneously build velocity and pre-stack reflectivity in the form of angle gathers of a subterranean formation. The velocity and angle gathers may be employed for quantitative interpretation. The velocity and vector reflectivity may be employed to determine relative impedance and relative density of the subterranean formation for prospectivity assessment. The acoustic wave equation may extend into the angle domain to build angle gathers of the subterranean formation with enhanced resolution and amplitude fidelity. The velocity, angle gathers, and vector reflectivity reveal the structure and lithology of features of the subterranean formation and may reveal the presence of oil and natural gas reservoirs.

Abstract: A method and apparatus includes: towing a first source with a source vessel; towing a second source with a survey vessel, the survey vessel following the source vessel by at least 5 km; towing a streamer spread at a first depth with the survey vessel; and towing a pair of long-offset streamers at a second depth and following the source vessel by at least 5 km, wherein: the first depth is 10 m to 30 m, and the second depth is greater than 30 m. A method and apparatus includes: towing a first source with a source vessel; towing a second source with a survey vessel, the first source and the second source being separated by at least 5 km; towing a streamer spread at a first depth with the survey vessel; towing a pair of long-offset streamers at a second depth, wherein: the first depth is between 10 m and 30 m, and the second depth is greater than 30 m; acquiring long-offset data with long-offset sensors distributed along the long-offset streamers; and constructing a velocity model with the long-offset data.

Abstract: This disclosure presents a streamer filler material that is a low density gel formed from a two-part, mix-curable polymer, and methods of making streamers using such materials. One embodiment of the filler material features a two-part silicone gel mixed with a paraffinic oil. The two-part silicone gel can make up 15% to 25%, by weight or volume, of the mixture. Methods of making such materials include forming a first unreactive mixture having a first reactant, promoter, and/or catalyst and a second unreactive mixture having a second reactant, promoter, and/or catalyst and mixing the first and second mixtures in a paraffinic oil system to make a gel. The streamer can be loaded with the filler by pumping or extruding the mixture.

Abstract: A method includes: towing sources in a wide-tow source survey configuration; actuating at least one of the sources to create a signal; detecting the signal with a first receiver of a first plurality of streamers; and detecting the signal with a second receiver of a second plurality of streamers, wherein: the second plurality of streamers are interspersed with streamers from the first plurality of streamers in the port outer region and in the starboard outer region. A system includes: sources in a wide-tow source survey configuration and coupled to the survey vessel; a first plurality of streamers comprising a regular streamer spread and coupled to the survey vessel; and a second plurality of streamers coupled to the survey vessel, wherein: the second plurality of streamers are interspersed with streamers from the first plurality of streamers in the port outer region and in the starboard outer region.

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: Embodiments generally relates to marine geophysical surveying. More particularly, the present disclosure relates to treatment of geophysical equipment with medetomidine compounds for reduction of marine growth. A method may comprise combining at least a medetomidine compound and a wax to form a mixture; and forming an outer layer disposed on a marine geophysical equipment, wherein the outer layer comprises the mixture of the medetomidine compound and the wax.

Abstract: A proposed geometrical distribution for a first non-impulsive source and a second non-impulsive source of a source array can be received. A near-field-to-notional computation can be performed for the proposed geometrical distribution to yield a respective computed notional output of the first and second non-impulsive sources. Whether the computed notional output of the first non-impulsive source has a first amount of residue greater than a threshold amount of residue can be determined. Whether the computed notional output of the second non-impulsive source has a second amount of residue greater than the threshold amount of residue can be determined. An indication whether either of the first or second amounts of residue is less than or equal to the threshold amount of residue can be provided.

Abstract: A marine seismic survey comprises towing a first source and a first streamer spread having a length L behind a first vessel. Sensors in the streamer spread record signals from the first source over a range of offset distances X to X+L. A second source is towed behind a second vessel that does not tow a streamer spread. Sensors in the streamer spread record signals from the second source over a range of offset distances A+L to A+2L. Sensors in the streamer spread do not record signals over a range of offset distances X+L to A+L from any active seismic sources used in the marine seismic survey.

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.