Abstract: Methods of designing seismic survey and acquisition of seismic data with reduced noise using equally or optimally irregularly spaced sources or receivers are described. Specifically, prime number ratios for the station to line spacing is used to prevent harmonic leakage and other noise contaminations in the acquired seismic data.

Abstract: Computational systems and methods for randomizing the order in which multiple sources are fired in simultaneous source acquisition are described. In one aspect, pseudo-randomly shifted time delays are generated for each shot interval of a marine-survey-time line. Each shifted time delay is assigned to one or the sources. The sources within each shot interval are fired based on the shifted time delays.

Abstract: A seabed object detection system is provided. The system can include a source array. The source array can include a first source and a second source. The system can include a data processing system including one or more processors. The data processing system can determine a position of the first source and can identify a first firing time of the second source. The data processing system can initiate a first source shot of the first source at a known position and the second source at a known time. The data processing system can determine a target position and estimated position for the first source. The data processing system can determine a second position of the first source based on a difference between the target position and the estimated position. The data processing system can initiate a second source shot of the first source at a known position.

Abstract: A simultaneous sources seismic acquisition method is described that introduces notch diversity to improve separating the unknown contributions of one or more sources from a commonly acquired set of wavefield signals while still allowing for optimal reconstruction properties in certain diamond-shaped regions. In particular, notch diversity is obtained by heteroscale encoding.

Abstract: A technique for use in geophysical surveying includes imparting a plurality of humming seismic signals and a plurality of low-frequency seismic signals into a geological formation. The technique also includes receiving returned seismic energy of the plurality of humming seismic signals and the plurality of low-frequency seismic signals after interacting with the geological formation and recording the returned seismic energy.

Abstract: A seabed object detection system can include a source array and a data processing system. The source array can include a first source and a second source. The data processing system can include one or more processors. The data processing system can determine a first position of the first source and can identify a first firing time of the second source. The data processing system can initiate a first source shot of the first source at the first position and the second source at the first firing time. The data processing system can determine a target position and estimated position for the first source. The data processing system can determine a second position of the first source based on a difference between the target position and the estimated position. The data processing system can initiate a second source shot of the first source at the second position.

Abstract: Seismic data are acquired using a seismic source comprising a plurality of seismic sub-sources disposed in a body of water at a plurality of depths and activated with different time delays. Far-field signatures are determined for the plurality of seismic sub-sources at each of the plurality of depths. A composite ghost-free far-field signature of the seismic source is determined from the far-field signatures for the plurality of seismic sub-sources at each of the plurality of depths and different time delays.

Abstract: Techniques are disclosed relating to geophysical surveying. In some embodiments, a marine survey vessel tows multiple sensor streamers in addition to vibratory sources deployed relative to the sensor streamers. In some embodiments, the vessel tows vibratory sources emitting energy within different frequency bands in different deployment zones. In some embodiments, one or more sources are driven with different sweep functions, different activation patterns, and/or different sweep lengths. Various disclosed techniques for manufacturing a geophysical data product may potentially simplify equipment used for towing sources, reduce survey complexity without reducing resolution, increase resolution without increasing survey complexity, improve energy content recovered from deep reflections, and/or reduce the environmental impact of emitting seismic energy.

Abstract: Determining a far field signature of a source array can include receiving data associated with a sea surface state and determining a coherent portion and an incoherent portion of a reflection coefficient of the sea surface based on the received data. A notional source signature of each source of the source array can be determined based on the coherent portion, the incoherent portion, and near field data associated with each of the sources, and the far field signature of the source array can be determined based on the notional source signatures of each of the sources. The notional source signature and the far field signature can be stored. A seismic image of a subsurface location can be generated based on the determined far field signature.

Abstract: Seismic data are acquired by actuating a first source at a first time and one or more additional seismic sources each with their own characteristic times with respect to a time of signal recording, the sources substantially collocated and at different depths. A first wavefield is determined that would occur if the first source were actuated at a selected time with respect to an initiation time of the recordings and being time adjusted for the water depth. One or more additional wavefields are determined that would occur if the one or more additional sources were each actuated at said selected time with respect to said initiation time, and being time adjusted for water depths of the one or more additional sources. The first wavefield and the one or more additional wavefields are combined to determine a deghosted source wavefield corresponding to actuation of a single seismic energy source.

Abstract: Methods and systems for marine survey acquisition are disclosed. In one embodiment, a method is provided that may deploy a marine seismic spread that includes a first seismic source, a second seismic source and a streamer with a receiver. The second source may be disposed at a distance from the first seismic source in an inline direction. The distance may be selected to produce one or more pairs of shot points during a seismic survey. The shot points within a pair may be disposed within a range that is used to calculate a pressure source gradient between the shot points within the pair. The method may shoot the first seismic source and the second seismic source substantially simultaneously. The method may record seismic data associated with shooting the first seismic source and the second seismic source. The method may calculate the pressure source gradient for respective pairs of shot points.

Abstract: Top-mount cable management structures are provided to mount to an upper surface of an electronics rack, over a cable pass-through in the upper surface. The cable management structure includes a base structure to mount to the upper surface of the rack, and reside over the cable pass-through. The base structure includes a sidewall with at least one cable opening to allow one or more cables which pass-through the cable pass-through to also pass-through the sidewall of the base structure. A cover structure is provided mounted to the base structure. The base and cover structures together define a substantially enclosed housing disposed over the cable pass-through when the cable management structure is operatively positioned over the upper surface of the electronics rack and the one or more cables pass-through the at least one cable opening in the sidewall of the base structure.

Abstract: Methods and systems for computing notional source signatures from modeled notional signatures and measured near-field signatures are described. Modeled near-field signatures are calculated from the modeled notional signatures. Low weights are assigned to parts of a source pressure wavefield spectrum where signatures are less reliable and higher weights are assigned to parts of the source pressure wavefield spectrum where signatures are more reliable. The part of the spectrum where both sets of signatures are reliable can be used for quality control and for comparing the measured near-field signatures to modeled near-field signatures. When there are uncertainties in the input parameters to the modeling, the input parameters can be scaled to minimize the differences between measured and modeled near-field signatures.

Abstract: Marine seismic vibrators in a marine seismic vibrator array for use in a seismic survey are activated to produce a source gradient wavefield to survey a target structure. The seismic survey may comprise a marine seismic survey conducted in a body of water.

Abstract: According to an embodiment, there is provided a system and method of collecting seismic data using a predetermined pattern of source activations that is intended to control the properties of the resulting seismic signal. One embodiment utilizes a seismic source array (or, more generally, any collection of controllable sources) to create a series of spaced apart in time source activations, with the spacing and number of such activations being used to shape the resulting signal. In one method of building sweeps, the guns are fired at an increasing rate (decreasing time separation) as time goes by. Other patterns may be generated by decreasing the firing rate as time goes by, or some combination of the foregoing. In an embodiment, the rate of the increase or decrease in the firing rate will change from pattern to pattern.

Abstract: Variable depth multicomponent sensor streamer. At least some of example embodiments including perform a geophysical survey by: setting a first target depth for first depth positioning device of a sensor streamer, the first depth positioning device associated with a first sensor of the sensor streamer, the first sensor at a first offset, and the first target depth based on tension in the sensor streamer proximate the first sensor; setting a second target depth for a second depth positioning device of the sensor streamer, the second depth positioning device associated with a second sensor of the sensor streamer, the second sensor at a second offset greater than the first offset, the second target depth based on tension in the sensor streamer proximate the second sensor, and the second target depth greater than the first target depth; towing the sensor streamer through the water; and obtaining data from the sensors.

Abstract: Heat sinks that cool electronics are mounted within a subsea housing or vessel. Springs are used to provide pressure between the heat sinks and a vessel wall. Vessel wall deformation caused by external seawater pressure is absorbed by the springs, which maintain a pre-load force according to the spring characteristics. The mechanism also allows for rack mounting of the electronics without the need for manual access in the relatively compact vessel or housing.

Abstract: Systems and methods for acquiring blended and unblended seismic data during a single seismic survey. The blended and unblended seismic data is generated with a plurality of sources that are fired in a dedicated sequence. The sequence involves firing all the sources at a first time, advancing the sources along a given path, firing only a first source at a second time, later than the first time, advancing the sources, firing again all the sources at a third time, later than the second time, advancing the sources, firing only a second source at a fourth time, later than the third time, and so on until a desired subsurface is fully surveyed.

Abstract: The output spectrum of a controllable swept-frequency acoustic source at a given frequency can be controlled by making the rate of change of frequency equal to the desired output power spectrum divided by the squared envelope amplitude of the source output signal, both measured at the time after the start of its frequency sweep at which the sweep frequency passes through the given frequency. The system and method can also be used to correct for propagation effects outside the source by dividing the desired spectrum by the propagation effect. The method can further be used either to obtain an output spectrum of a desired shape from a source operating at maximum output or to design a sweep of a minimum feasible duration that will result in an output spectrum of a specified shape and with a specified amplitude.

Abstract: Wide azimuth data acquisition systems using at least three streamer sets achieve shorter survey time and enhanced angular coverage relative to conventional systems using two streamer sets. Various techniques such as high-density seismic source activation and alternating surveyed bands with skipped bands lead to data quality similar to the conventional system, while maintaining the increased productivity advantage.

Abstract: A method for calculating intermodulation noise generated with one or more land seismic sources. The method includes receiving seismic data (g) generated by actuating the one or more land seismic source with a single sweep; selecting a number of detectors (a-f) that detect a subset (ga-gf) of the seismic data (g); estimating earth responses (ha1-hf1) based on (i) the subset seismic data (ga-gf) and (ii) a ground force (gf) of the one or more land seismic source; calculating plural intermodulation noises (noiseA1-noiseF1) for the number of detectors based on the earth responses (ha1-hf1); and removing the plural intermodulation noises (noiseA1-noiseF1) from corresponding detector signals (ga-gf) to mitigate the intermodulation noise effect.

Abstract: Seismic data are acquired using a seismic source comprising a plurality of seismic sub-sources disposed in a body of water at a plurality of depths and activated with different time delays. Far-field signatures are determined for the plurality of seismic sub-sources at each of the plurality of depths. A composite ghost-free far-field signature of the seismic source is determined from the far-field signatures for the plurality of seismic sub-sources at each of the plurality of depths and different time delays. A source response is removed from the seismic data using the far-field signatures of the seismic source.

Abstract: Wide azimuth data acquisition systems using at least three streamer sets achieve shorter survey time and enhanced angular coverage relative to conventional systems using two streamer sets. Various techniques such as high-density seismic source activation and alternating surveyed bands with skipped bands lead to data quality similar to the conventional system, while maintaining the increased productivity advantage.

Abstract: A method for detecting faults of individual wave sources in a marine source array includes acquiring near-field data using sensors, the sensors being located near the individual wave sources. The method further includes generating an index for each of the individual wave sources based on (A) the near-field data and (B) information on the geometry of the marine source array that enables localizing the individual wave sources and respective sensors relative to one another. The method also includes comparing the index for each of the individual wave sources with a corresponding reference index for determining whether a fault has occurred.

Abstract: The invention relates to continuously or near continuously acquiring seismic data where at least one pulse-type source is fired in a distinctive sequence to create a series of pulses and to create a continuous or near continuous rumble. In a preferred embodiment, a number of pulse-type seismic sources are arranged in an array and are fired in a distinctive loop of composite pulses where the returning wavefield is source separable based on the distinctive composite pulses. Firing the pulse-type sources creates an identifiable loop of identifiable composite pulses so that two or more marine seismic acquisition systems with pulse-type seismic sources can acquire seismic data concurrently, continuously or near continuously and the peak energy delivered into the water will be less, which will reduce the irritation of seismic data acquisition to marine life.

Abstract: A method controls a delay of an air-gun in an aquatic seismic source. The method includes a step of receiving an attribute of the air-gun during the aquatic seismic survey; a step of calculating, based on a time-delay algorithm that uses the attribute, the asynchronization time of the air-gun; a step of determining whether the asynchronization time is smaller than a given time threshold; a step of instructing a controller to (1) wait for a predetermined time before calculating again the asynchronization time of the air-gun if the asynchronization time is smaller than the given time threshold, or (2) calculate an updated asynchronization time for the air-gun based on the attribute if the asynchronization time is larger than the given time threshold; and a step of sending the updated asynchronization time to a gun controller of the air-gun for adjusting a delay time for firing the air-gun.

Abstract: A method of processing seismic data acquired consequent to actuation of a seismic source is described. The method comprises taking the result of the following process into account when processing the seismic data where the process comprises estimating the effect of uncertainty in the position and/or orientation of the seismic source relative to the measuring receiver on processing the seismic data by estimating a source wavefield from data acquired by a near-field measuring receiver and from a first parameter set including at least one parameter indicative of the position and/or orientation of the seismic source relative to the measuring receiver, varying the value of at least one parameter of the first parameter set, estimating the source wavefield from the data acquired by the measuring receiver and from the varied first parameter set and obtaining information about the uncertainty in the estimate of the source wavefield.

Abstract: A method for acquiring marine seismic data includes towing a seismic energy source in a body of water and towing a seismic sensor at a selected distance from the seismic energy source. The seismic energy source is actuated a plurality of positions, a distance between each of the plurality of actuations being randomly different than any other such distance. Seismic energy detected by the seismic sensor is substantially continuously recorded through a plurality of actuations of the at least one seismic energy source. The recording includes recording a geodetic position of the at least one seismic energy source and the at least one seismic sensor at each actuation.

Abstract: System and method for actuating first and second marine acoustic sources in a firing sequence, the firing sequence including at least a first actuation of the first source followed by a first actuation of the second source followed by a second actuation of the first source and a second actuation of the second source. The method includes towing the first source at a depth in water substantially equal to a depth of the second source; establishing a series of reference time instants; actuating the first source with a variable first time delay relative to the series of reference time instants; and actuating the second source with a variable second time delay relative to the series of reference time instants such that time intervals between consecutive activations of the first and second sources are also variable.

Abstract: A method and a system of acquiring and processing multi-source broadband marine seismic data in such a way that at least a part of said acquired data is partially or fully de-ghosted on the receiver side and then partially or fully re-assembled to a pre-stack dataset. At least one non-uniformly horizontal streamer is towed and at least two seismic sources emit seismic signals at spaced apart positions. Further presented is a method of processing marine seismic data by using the thus resulting notch diversity in these two (or more) seismic records to de-ghost the dataset, gathering two or more recorded seismic signals having substantially the same source-sensor offset and substantially the same common mid-point at different sensor depths, the sensor depths at least different enough to enable identification of seismic signals originating from ghosting. The gather is de-ghosted, thus obtaining seismic data with significantly broader bandwidth.

Abstract: A technique facilitates the acquisition of seismic data at a substantially reduced source volume. The methodology generally comprises conducting a seismic survey with seismic sources that have a reduced source volume to collect seismic data. The low frequency data which is lost due to the reduced source volume is replaced with data acquired from a complementary method, such as a receiver-side acquisition method. The two sets of data are combined to provide a comprehensive seismic survey image without requiring conventional seismic source volume.

Abstract: Method and marine acoustic source array for generating an acoustic wave in a body of water. The marine acoustic source array includes a first depth sub-array set of first acoustic source points configured to be provided at a first depth (z1), the first acoustic source points having different inline first locations along a longitudinal axis (X); and a second depth sub-array set of second acoustic source points configured to be provided at a second depth (z2), the second acoustic source points having different inline second locations along the longitudinal axis (X). The first locations do not coincide along the longitudinal axis (X) with any of the second locations.

Abstract: A disclosed subsurface imaging method begins by obtaining initial signals from a geophysical survey that has been acquired with multiple geophysical energy sources actuated in a plurality of firing sequences, each sequence having a known time delay between the firing times of each source. The initial signals are grouped into gathers of signals acquired from multiple firing sequences. For each gather, initial estimates of the first and second source wave fields are determined. Quieted signals for the first source are then generated to represent the initial signals minus a current estimate of the second source wave field. A coherent energy separation operation is applied to the quieted signals to obtain a refined estimate for the first source wave field.

Abstract: A device is provided for producing an acoustic signal in a liquid medium. The device includes a pneumatic chamber to contain a compressed gas volume, at least one pneumatic exhaust port allowing the compressed gas volume to be released out of the pneumatic chamber, and a shuttle movable along a translational axis during an opening phase, between two positions: a closed position in which the compressed gas volume is enclosed within the pneumatic chamber, and an open position in which the compressed gas volume is released out of the pneumatic chamber through the pneumatic exhaust port, to produce the acoustic signal in the liquid medium. A hydraulic brake is used to brake the shuttle during the opening phase. The hydraulic brake includes a hydraulic chamber and having a hydraulic exhaust area of a hydraulic volume out of the hydraulic chamber, and includes a control for controlling the acoustic signal.

Abstract: There is a method for obtaining control of a source array configured to generate seismic waves. The method includes accessing an interface unit attached to a fixed structure that is substantially stationary in water, the interface unit being connected to a source array; entering a passcode to the interface unit to gain access to the source array; downloading a shooting sequence or a driving signal to a controller of the source array; and actuating the source array to generate seismic energy into water.

Abstract: A technique enables measuring of the actual firing sequence times in a seismic survey application. The actual firing sequence times are then employed in simultaneous source resolution methods. For example, simultaneous seismic sources may be deployed in a survey region. The seismic sources are then fired, and the actual firing times are determined and recorded for use in optimizing the seismic survey.

Abstract: Method for marine seismic acquisition using both monopole (91) and dipole (92) source types. Through a combination of source design and operation and/or combination or summing of the data in a processing step, the source ghost is either attenuated or, if desired, enhanced (93). The properties of the two different source types allow them to be adjusted so that the first down going wave from each has either opposite polarity or the same polarity, whereas the source-ghost wave will have, respectively same polarity or opposite polarity. This allows cancellation or enhancement of the source ghost. If the survey also employs two-component sensor acquisition, then the combined data sets may be both sensor de-ghosted and source de-ghosted.

Abstract: The maximum output of a seismic source array may be reduced by activating the individual seismic sources within these seismic source array in a pattern that is extended in time rather than by the presently employed conventional simultaneous activation of a large number of individual seismic sources. Methods are disclosed which take data shot with patterned sources and may use a sparse inversion method to create data with the about same image quality as that of conventional sources. In this manner the output of the maximum impulse of a seismic source array may be reduced by an amplitude factor of about 10 in the examples shown here, corresponding to a reduction of about 20 dB while maintaining virtually the same seismic image quality. The disclosed methods may be used in combination with any simultaneous sourcing technique. In addition, the disclosed methods may be used with a plurality of source arrays.

Abstract: Method for generating an excitation signal for a first vibratory seismic source so that the first vibratory seismic source is driven with no listening time. The method includes a step of determining a first target spectrum for the first vibratory seismic source; a step of setting a first group of constraints for the first vibratory seismic source; and a step of generating a first excitation signal for the first vibratory seismic source based on the first group of constraints and the first target spectrum. The first seismic traces recorded with plural receivers can be identified when the first vibratory seismic source is driven with no listening time, based on the first excitation signal.

Abstract: Method and marine acoustic source array for generating an acoustic wave in a body of water. The marine acoustic source array includes at least one sub-array. The at least one sub-array includes a float from which plural source points are attached. The source points may be provided on a curved line, straight line, or other desired shape so that a variable-depth source is obtained with a single float. The source points may be divided into groups and the groups may be provided on the curved line, straight line or other desired shape.

Abstract: Controller and method for determining a driving signal of a vibro-acoustic source element that is configured to generate acoustic waves in water. The method includes estimating at least one physical constraint of the vibro-acoustic source element; modeling a ghost function determined by a surface of the water; setting a target energy spectrum density to be emitted by the vibro-acoustic source element during the driving signal; and determining the driving signal in a controller based on at least one physical constraint, the ghost function, and the target energy spectrum density.

Abstract: Methods and apparatus for generating borehole seismic surveys are disclosed. The methods and apparatus enable more accurate surveys than previous surveying systems. In some embodiments, firing of remote seismic sources is synchronized with data recording in a borehole. In some embodiments, the synchronization is based on a universal time standard. In some embodiments, GPS positioning technology is used to predict firing times and synchronize firing times with downhole and surface recording.

Abstract: Controller and method for adapting a frequency sweep for a vibro-acoustic source element that is configured to generate acoustic waves during a seismic survey. The method includes driving a seismic source element to generate a current frequency sweep; recording seismic data with plural seismic sensors in response to the current frequency sweep; selecting, during the seismic survey, a data subset of the seismic data, wherein the data subset has a size less than 10% of the seismic data; calculating with a processing device an attribute based on the data subset; and calculating a new frequency sweep based on the attribute.

Abstract: A technique facilitates obtaining seismic data in a marine environment. An array of acoustic sources is deployed in a marine environment. The array can be utilized for creating acoustic pulses that facilitate the collection of data on subsea structures. The methodology enables optimization of acoustic source array performance to improve the collection of useful data during a seismic survey.

Abstract: Control mechanisms, computer software and methods for driving vibrational source arrays underwater. An incoherent acquisition scheme drives individual source elements simultaneously and incoherently while a coherent acquisition scheme drives high-frequency individual source elements simultaneously and incoherently and low-frequency individual source elements simultaneously and coherently. Thus, denser coverage and an increased energy input is achieved for the source arrays.

Abstract: Method for generating an excitation signal for a first vibratory seismic source so that the first vibratory seismic source is driven with no listening time. The method includes a step of determining a first target spectrum for the first vibratory seismic source; a step of setting a first group of constraints for the first vibratory seismic source; and a step of generating a first excitation signal for the first vibratory seismic source based on the first group of constraints and the first target spectrum. The first seismic traces recorded with plural receivers can be identified when the first vibratory seismic source is driven with no listening time, based on the first excitation signal.

Abstract: A technique facilitates obtaining seismic data in a marine environment. An array of acoustic sources is deployed in a marine environment. The array can be utilized for creating acoustic pulses that facilitate the collection of data on subsea structures. The methodology enables optimization of acoustic source array performance to improve the collection of useful data during a seismic survey.

Abstract: A method for managing a multi-vessel seismic system including a first vessel, having a recording system and towing a streamer integrating seismic sensors, and a second vessel, including at least one seismic source performing shots. The second vessel sends to the first vessel a plurality of series of shot predictions. For each shot, the second vessels activates the seismic source according to the predictions and sends to the first vessel shot data relating to the shot. The first vessel activates the recording system. If the first vessel has not received the shot data relating to at least one performed shot, it sends a request to the second vessel and receives in response the missing shot data. For each performed shot and the related shot data, the system selects seismic data and combines the selected seismic data with the related shot data to obtain combined data allowing a seabed representation.

Abstract: Control mechanisms, computer software and methods for driving vibrational source arrays underwater. An incoherent acquisition scheme drives individual source elements simultaneously and incoherently while a coherent acquisition scheme drives high-frequency individual source elements simultaneously and incoherently and low-frequency individual source elements simultaneously and coherently. Thus, denser coverage and an increased energy input is achieved for the source arrays.

Abstract: A method and apparatus for acquiring seismic data. In one embodiment, the method includes: moving a first air gun array in the water at a first depth and a second air gun array in the water at a second depth greater than the first depth, in which the total volume of the first air gun array is less than the total volume of the second air gun array, in which the first air gun array is separated from the second air gun array by a distance substantially equal to a shot point interval, firing seismic energy through the first and second air gun arrays through the water into the earth, and recording seismic signals reflected from strata in the earth beneath the water.