Abstract: This disclosure presents processes and systems for estimating a source wavelet from seismic data recorded in a seismic survey of a subterranean formation. In one aspect, a base wavelet is determined based on recorded seismic traces obtained in a seismic survey of a subterranean formation. Processes and systems include a phase-only wavelet based on the base wavelet and the recorded seismic data. An estimated source wavelet is obtained by convolving the base wavelet with the phase-only wavelet. Properties of the subterranean formation are determined based on the estimated source wavelet and the recorded seismic data.

Abstract: Embodiments may be directed to marine geophysical surveying and associated methods. At least one embodiment may be directed to incorporation of a lock mechanism in a sensor streamer that interlocks the outer jacket with one or more of the spacers to prevent relative rotation between the outer jacket. An embodiment may provide a sensor streamer that includes an outer jacket, a plurality of spacers, and a locking mechanism. The outer jacket may be elongated in an axial direction and comprise an outer jacket surface and an inner jacket surface. The plurality of spacers may be positioned in the outer jacket at spaced apart locations in the axial direction, wherein each of the plurality of spacers comprises a spacer body having an outer spacer surface. The locking mechanism may interlock the outer jacket with at least one of the plurality of spacers.

Abstract: Sensor receiver nulls and null steering. One example embodiment is method in which a direction from a sensor position to a noise source is determined. A coordinate rotation is applied to a first set of signal values, wherein each signal value of the first set of signal values is based on an output of a corresponding component of a three-component particle motion sensor at the sensor position. The applying generates a rotated set of signal values. The coordinate rotation comprises a coordinate rotation transforming a first set of coordinate axes to a second set of coordinate axes, wherein the first set of coordinate axes has each coordinate axis aligned with a corresponding component of the three-component particle motion sensor at the sensor position, and the second set of coordinate axes comprises a first axis pointed in a direction opposite the direction from the sensor position to the noise source.

Abstract: Processes and systems are described for generating an image of a subterranean formation from seismic data recorded during a marine survey that employed a moving vibrational source. Processes and systems compute an up-going pressure wavefield from pressure data and vertical velocity data recorded in the marine survey. A direct incident downgoing vertical velocity wavefield that includes Doppler effects created by the moving vibrational source and characterizes a source wavefield and source ghost of the moving vibrational source is computed and deconvolved from the upgoing pressure wavefield to generate a subsurface reflectivity wavefield. The subsurface reflectivity wavefield is effectively free of contamination from the source wavefield, the source ghost, and the Doppler related effects.

Abstract: Marine surveys carried out with multiple source arrays comprising three or more sources are discussed. Each source of a multiple source array is an array of source elements, such as air guns. The sources of a multiple source array may be arranged in particular type of configuration that is effectively maintained while the survey vessel travels a sail line. The sources of the multiple source array are activated to acoustically illuminate a subterranean formation with acoustic signals. Two or more sources of a multiple source array may be activated to create blended seismic data. Methods to deblend, source deghost, and attenuate noise in the blended seismic data obtained by using a multiple source array are also discussed.

Abstract: Techniques are disclosed relating to calibrating sensors configured to measure both pressure and acceleration. In various embodiments, a system detects a first voltage produce by a first piezoelectric material in a hydrophone when the hydrophone is exposed to an acceleration and detects a second voltage produced by a second piezoelectric material in the hydrophone when the hydrophone is exposed to the acceleration. The system, in some embodiments, compares the first voltage and the second voltage. Based on the comparing of the first and second voltages, in some embodiments, the system determines a resistance for a variable resistor coupled to one of the first and second piezoelectric materials.

Abstract: Techniques are disclosed relating to geophysical surveying. In various embodiments, a computer system may access seismic data for a geological formation, where the seismic data is recorded, using one or more sensors, during a seismic survey in which a first vibratory source was driven using a first digital code for at least a first time interval. The first digital code, in some embodiments, may include a first plurality of subsections corresponding to portions of the first time interval. In some embodiments, the computer system may image a first location of the geological formation using a correlation of only a first sub-section of the first plurality of sub-sections with the seismic data. Further, in some embodiments, the computer system may image a second location of the geological formation using a correlation of two or more of the first plurality of sub-sections with the seismic data.

Abstract: Calibration based on twist and orientation for towed object can include determining an amount of twist as a function of length of a portion of a towed object based on output of tilt sensors in the portion of the towed object and a model that describes the twist along the portion of the towed object. An orientation of a seismic sensor can be determined based on the determined amount of twist and a position of the seismic sensor along a length of the portion of the towed object. The seismic sensor can be calibrated based on the orientation.

Abstract: Geophysical survey methods. At least some of the example embodiments are methods of performing a marine geophysical survey including: towing a plurality of sensor streamers behind a tow vessel, each sensor streamer coupled to the tow vessel by a respective lead-in cable; towing, by the tow vessel, a plurality of lead vessels with each lead vessel pulling a respective seismic source, each lead vessel pulled by a respective tow cable and at least one intermediate cable; actuating the respective seismic sources pulled by the plurality of lead vessels; and gathering seismic data by each of the sensor streamers.

Abstract: Inversion with exponentially encoded seismic data can include exponentially encoding acquired seismic data and associated synthetic seismic data, storing the exponentially encoded acquired seismic data and the exponentially encoded associated synthetic seismic data, determining a one-dimensional (1D) Wasserstein distance between the exponentially encoded acquired seismic data and the exponentially encoded associated synthetic seismic data, and generating an adjoint source based on the 1D Wasserstein distance. The example method also includes adapting a dynamic weight implementation of a sensitivity kernel to the adjoint source to build a gradient associated with the acquired seismic data and the associated synthetic seismic data, and iteratively inverting a waveform associated with the exponentially encoded acquired seismic data and the exponentially encoded associated synthetic seismic data based on the gradient. An image of a subsurface location can be generated based on results of the iterative inversions.

Abstract: A marine vibrator may include a containment housing, a sound radiating surface, and a compliance chamber. The compliance chamber may include a compliance chamber housing, a non-linear linkage assembly, and a low pressure chamber. The compliance chamber housing may define at least a portion of a compliance chamber internal volume having a compliance chamber internal gas pressure. The low pressure chamber may comprise a low pressure piston and a low pressure chamber housing. The low pressure chamber housing may define at least a portion of a low pressure chamber internal volume having a low pressure chamber internal gas pressure. The low pressure piston may be configured to move in response to a pressure differential across the low pressure piston such that a resonance frequency of the marine vibrator may be changed.

Abstract: Survey design for data acquisition using marine non-impulsive sources can include operating a first marine non-impulsive source at over a first frequency range for a first sweep length and operating a second marine non-impulsive source over a second frequency range for a second sweep length. The first sweep length can be based on available geological information of a subsurface location that is a target of a marine seismic survey, an intended speed of a marine survey vessel, and the first frequency range. The second sweep length can be based on the available geological information, the intended speed, and the second frequency range.

Abstract: Processes and systems for deblending blended seismic data with attenuated source signatures and source ghost are described. Processes and systems compute blended upgoing pressure wavefield based on blended pressure wavefield and blended vertical velocity wavefield recorded in a marine survey of a subterranean formation. Downgoing vertical velocity wavefield is computed based on near-field pressure wavefields generated by source elements of sources activated in the marine survey. Deblended wavefield is computed based on the blended upgoing pressure wavefield and the downgoing vertical velocity source wavefield. The deblended wavefield may be used to generate an image of the subterranean formation with the source signatures and source ghosts contained in the blended pressure wavefield and blended vertical velocity wavefield.

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: Estimating an earth response can include deconvolving a multi-dimensional source wavefield from near-continuously recorded seismic data recorded at a receiver position. The deconvolving can include spreading the near-continuously recorded seismic data across a plurality of possible source emission angles. The result of the deconvolution can be the earth response estimate.

Abstract: Techniques are disclosed relating to control of seismic sources such as marine vibrators. According to some embodiments, iterative learning control (ILC) systems may be used to control such seismic sources. According to some embodiments, local sensor(s) placed in, on, or near a seismic source and/or remote sensors placed in the far-field region may be used to determine a transfer function for the seismic source for such ILC control. A sensor is configured to measure the acoustic output of the marine vibrator along with signal pulses from at least one impulsive seismic signal source. The ILC is disabled when it is determined that the impulsive seismic is active based on the sensor measurements.

Abstract: Techniques are disclosed relating to geophysical surveying. In various embodiments, a marine survey vessel may tow a plurality of streamers that each include a plurality of seismic sensors. Further, the survey vessel may tow a plurality of vibratory sources. In various embodiments, a first sweep may be performed, using one or more of the plurality of vibratory sources, for a first time interval. Further, in various embodiments, disclosed techniques may include recording, during the first time interval using the plurality of seismic sensors, seismic data on a tangible, computer-readable medium, thereby creating a geophysical data product.

Abstract: In the field of marine geophysical surveying, systems and methods for controlling the spatial distribution or orientation of a geophysical sensor streamer or an array of geophysical sensor streamers towed behind a survey vessel are provided. Various techniques for changing the spatial distribution or orientation of such geophysical sensor streamers in response to changing conditions are provided. For example, crosscurrent conditions may be determined based on configuration data received from positioning devices along the length of a streamer, and a new desired orientation for the streamer may be determined based on the crosscurrent conditions. The new desired orientation may include a new desired feather angle for the streamer.

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: Managing movement of data packets along a geophysical sensor cable. At least some embodiments include a geophysical sensor cable section having an internal volume within which geophysical sensors are disposed at spaced apart locations. A digitizer is disposed within the internal volume and is communicatively coupled to sensors. A telemetry unit within the internal volume is communicatively coupled to the digitizer. The telemetry unit may comprise multiple forward ports, multiple aft ports and a controller communicatively coupled to the forward ports, the aft ports, and the digitizer. The controller may be configured to: relay downstream-directed packets received on an active forward port through all aft ports; gather sensor data from the digitizer and send the sensor data as upstream-directed packets through the active forward port; and relay any upstream-directed packets received on aft ports through the active forward port.