Marine Seismic Streamer Research Articles

Combined onshore and offshore wide-scale seismic data acquisition and imaging for carbon capture and storage exploration in Havnsø, Denmark

Strong global actions for climate change include carbon capture and storage (CCS) as a feasible solution to reach carbon neutrality and raise opportunities for detailed subsurface investigations. An acquisition set-up designed for onshore-offshore zones was maximized for wide-scale high-resolution structural imaging and implemented to cover a domal structure of interest for CCS utilization close to the town of Havnsø (Denmark). The challenges of the combined acquisition and processing of land and marine multisensor data along a 42 km seismic profile are analyzed, the suggested solutions are applied, and the limitations are discussed. On the onshore side, a nodal array and a seismic landstreamer system were simultaneously used, whereas along the transition zone, a marine seismic streamer and ocean-bottom seismometers were added to record the seismic response generated by two seismic vibrator sources. The adopted sensing domains (velocity, acceleration, and pressure) were studied, and different processing steps were evaluated to enable their processing and subsequent data set merging. Results suggest, as the best approach, a separate prestack processing of the different data sets and the computation of new geometries and new surface-consistent residual static correction after their merging. The data acquired in the transition zone illuminate, for the first time, the subsurface geology of the region, delineating an expected domal closure. The final seismic section shows high continuity of the reflections with good resolution along the entire profile, identifying the main reservoir structure and the surrounding areas, which are important to ensure reservoir integrity and safe exploitation over longer time scales. Shallow and deep reflections are consistent with the stratigraphic column from a well log near the profile. The presented study shows a comprehensive workflow for processing such a multisensor data set in onshore and transition zone settings.

Numerical investigation of the effect of convex transverse curvature and concave grooves on the turbulent boundary layer along a cylinder in axial flow

Axisymmetric turbulent boundary layers that develop around streamwise oriented long cylinder-like objects can be found in many applications, such as towed array sonars or marine seismic streamers. In many of these applications, turbulent fluctuations within the boundary layer flow can have a negative impact compared with laminar flow conditions. The aim of the present work is to design a surface modification that influences the turbulent boundary layer around a cylinder in axial flow in order to reduce turbulent fluctuations. To design the surface we consider recent findings regarding the turbulence damping effects of groove-like surface structures and combine these insights with the effect of convex transverse curvature on turbulence. We use large-eddy simulations to investigate the flow around a cylinder of modified design and around a reference circular cylinder. Both flows have a radius-based Reynolds number of Rea≈1.23⋅104. The modified design leads to a 20 % decrease in the average wall shear stress and results in local reductions in the turbulent intensities, Reynolds stress, the temporal velocity spectrum, and the turbulent dissipation rate. The analysis within the anisotropy-invariant space reveals a tendency towards flow relaminarization. However, the new design has no effect on turbulent pressure fluctuations. We provide suggestions on how to further improve the surface design to achieve even greater flow stabilization.

Recent advances with wide-tow multi-sources in marine seismic streamer acquisition and imaging

Recent advances with wide-tow multi-sources in marine seismic streamer acquisition and imaging

The Design of the Marine Seismic Streamer Controller System Based on Ethernet Technology

The Design of the Marine Seismic Streamer Controller System Based on Ethernet Technology

Modeling and Research on Power System of Distributed Sensor Networks for Long Streamers in Marine Seismic Exploration.

The electric power system plays an important role in sensor networks. In the marine seismic exploration streamer system (MSESS), an underwater power system transmits high-voltage direct current to all nodes in the streamer through a daisy chain structure. As offshore oil exploration develops toward deep water, it is necessary to study long streamers with large-scale sensor networks for deep water exploration. When the length of a streamer is increased to a certain value, the output current of the power supply increases sharply. This results in the activation of the overcurrent protection and the power supply shuts down. This paper puts forward an accurate model for an underwater power system applied to MSESS. Using the Newton iteration algorithm and a reverse algorithm, equations established by the model are solved and laboratory test results are used to verify the accuracy of the model. Based on simulation and analysis of the model, we explain why the power system crashes when the streamer is too long. Software that can quickly calculate the maximum number of nodes (the maximum length with which the system works normally) is developed and it is significant for the design of MSESS. The method of research could also be applied to relevant work such as large-scale sensor networks with daisy-chaining power supply in land seismic exploration.

Imaging the Shallow Subsurface Structure of the North Hikurangi Subduction Zone, New Zealand, Using 2‐D Full‐Waveform Inversion

AbstractThe northern Hikurangi plate boundary fault hosts a range of seismic behaviors, of which the physical mechanisms controlling seismicity are poorly understood, but often related to high pore fluid pressures and conditionally stable frictional conditions. Using 2‐D marine seismic streamer data, we employ full‐waveform inversion (FWI) to obtain a high‐resolution 2‐D P wave velocity model across the Hikurangi margin down to depths of ~2 km. The validity of the FWI velocity model is investigated through comparison with the prestack depth‐migrated seismic reflection image, sonic well data, and the match between observed and synthetic waveforms. Our model reveals the shallow structure of the overriding plate, including the fault plumbing system above the zone of slow‐slip events to theoretical resolution of a half seismic wavelength. We find that the hanging walls of thrust faults often have substantially higher velocities than footwalls, consistent with higher compaction. In some cases, intrawedge faults identified from reflection data are associated with low‐velocity anomalies, which may suggest that they are high‐porosity zones acting as conduits for fluid flow. The continuity of velocity structure away from International Ocean Discovery Program drill site U1520 suggests that lithological variations in the incoming sedimentary stratigraphy observed at this site continue to the deformation front and are likely important in controlling seismic behavior. This investigation provides a high‐resolution insight into the shallow parts of subduction zones, which shows promise for the extension of modeling to 3‐D using a recently acquired, longer‐offset, seismic data set.

Position Prediction of Marine Seismic Streamer Cables Using Various Kalman Filter Methods

Abstract Towed seismic streamer cables are extensively employed for offshore marine petroleum exploration. With the increasing need for accurate streamer steering due to rising number and length of streamers and decreasing intrastreamer separation, as well as new types of survey configurations, accurate modeling, positioning, and path prediction of the streamers are imperative. In the present study, a variety of models and methods have been implemented and utilized for data assimilation of full-scale seismic streamer position data for a marine seismic streamer, followed by path prediction ahead of time. The methods implemented are described, including various models used with the Kalman filter, extended Kalman filter, and ensemble Kalman filter, with comparison and evaluation of prediction results. One particular method, the Path-In-the-Water ensemble Kalman filter (PIW-EnKF), appears to be the most robust method with good prediction results compared to the other methods, as well as having low computational cost. As a case study with full-scale data, the PIW-EnKF is further employed for estimation and prediction of a complete streamer spread.

Oilfield Service Patent Contests Get Heated

From the highest courts of the US judicial branch to the C-suite, contests involving patents have recently come to the fore in the innovation-hungry US oilfield services industry, even as filings and litigation have recently declined. In the past few months, the US Supreme Court has ruled on two disputes involving oilfield services firms, providing guidance on the extent to which patent protection applies beyond US borders and reaffirming a controversial process by which a patent’s validity is reexamined. The decisions come as companies adopt a more tactical approach in their pursuit and defense of intellectual property (IP). The most recent ruling, which came in June, found that Schlumberger’s geophysical services subsidiary WesternGeco could recover lost profits for infringement abroad of four of its US patents by rival Ion Geophysical. The technology in question involved control systems for marine seismic streamer steering devices, separately falling under WesternGeco’s Q-Marine brand and Ion’s DigiFin brand. Ion was shipping the components overseas to customers, which then assembled the technology for their own use. The first chapter of the saga came in 2012 when a federal jury ruled in favor of WesternGeco in its infringement suit against Ion, finding that the practice caused WesternGeco to lose multiple survey contracts. The case was turned on its head, however, when an appeal by Ion resulted in the US Court of Appeals for the Federal Circuit reversing the lost profit award. A subsequent appeal by WesternGeco elevated the case to the US Supreme Court. While Ion’s appeal was pending, the companies were involved in separate proceedings, initiated by Petroleum Geo-Services, that challenged the validity of the WesternGeco patents before the Patent Trial and Appeal Board (PTAB) under a process called inter partes review (IPR). Challenged in the other US Supreme Court decision this year involving oilfield service firms, IPR is a procedure that takes a patent challenge to the US Patent and Trademark Office (USPTO) rather than before a jury in a district court. The PTAB invalidated the four patent claims that formed the basis for the federal jury verdict, and, upon appeal by WesternGeco, the Federal Circuit in May determined that three of the four patents were invalid. Meanwhile, in the original case, the US Supreme Court in June ruled in a 7–2 decision that infringement did occur under Section 271 of the Patent Act—which covers the exporting of components for a patented invention for assembly abroad—and that WesternGeco was in fact entitled to lost-profit damages for infringement. The court determined that “the conduct in this case that is relevant to the statutory focus clearly occurred in the United States.” In a subsequent statement to JPT, Schlumberger said it was “pleased” with the high court’s decision. “More importantly,” the company said, the ruling “reinforces our position that, as a technology innovator, we receive the full protection of the Patent Act against those who infringe US patents.”

Comparison of Two Models for Prediction of Seismic Streamer State Using the Ensemble Kalman Filter

Towed marine seismic streamers are extensively utilized for petroleum exploration. With the increasing demand for efficiency, leading to longer and more densely spaced streamers, as well as four-dimensional (4D) surveys and more complicated survey configurations, the demand for optimal streamer steering has increased significantly. Accurate streamer state prediction is one important aspect of efficient streamer steering. In the present study, the ensemble Kalman filter (EnKF) has been used with two different models for data assimilation including parameter estimation followed by position prediction. The data used are processed position data for a seismic streamer at the very start of a survey line with particularly large cable movements due to currents. The first model is a partial differential equation (PDE) model reduced to two-dimensional (2D), solved using a finite difference method (FDM). The second model is based on a path-in-the-water (PIW) model and includes a drift angle. Prediction results using various settings are presented for both models. A variant of the PIW method gives the overall best results for the present data.

Full waveform inversion comparison of conventional and broadband marine seismic streamer data, NW Shelf Australia

In this paper, we illustrate the application of frequency- domain FWI to two 2D data sets acquired simultaneously offshore North West Australia (NWA); one data set was recorded with a conventional streamer, and the other with the use of variable depth streamer configuration. First we discuss the two data sets, and our frequency-domain FWI algorithm. We then present each FWI result, and discuss the superiority of the broadband FWI results obtained with the variable depth streamer data. SUMMARY The lack of low-frequency information in conventional marine seismic streamer data inhibits the success of frequency-domain full waveform inversion (FWI). Low frequencies are typically absent in marine seismic data due to the low-cut spectral responses of airgun sources and hydrophone receivers, and the fact that the air-water interface produces source and receiver ghost reflections which create notch frequencies in the data amplitude spectrum. Advances in broadband streamer acquisition, such as the variable depth towed streamer, allow us to extend the low and high bounds of the useful frequency bandwidth in the seismic data spectrum. We illustrate the application of frequency-domain FWI to two 2D seismic data sets acquired simultaneously offshore North West Australia. Both data sets were acquired together, one with a conventional streamer, and the other with a variable depth streamer configuration. Our examples demonstrate that the FWI results are clearly superior when using the broadband variable depth streamer data, compared to using the conventional streamer data.

Research on improving conventional marine seismic streamer data imaging quality using OBS data from Northern South China Sea

It is very important to convert the seismic data from the time domain to the depth domain. Here we discuss the approaches of inverse modeling of travel times for determination of the P-wave velocity (Vp) using OBS data, and also using the inverted velocity to improve the conventional marine seismic streamer data imaging quality. The migration section of the single channel seismic data is used to define the model horizons and help to control their geometry. Wide angle hydrophone data of OBS are used to determine P-wave travel times. The picked travel times from various shots are inverted for P-wave interval velocities using RayInvr, which calculated theoretical travel times via ray tracing. Damped least squares optimization is performed to fine tune the fits between observed and calculated travel times. In the end, two conventional marine seismic streamer data's migration sections are compared and the result shows that the section using the inverted velocity of OBS data is much better than that using the velocity of conventional velocity analysis method to the streamer data.

Multisensor streamer recording and its implications for time-lapse seismic and repeatability

Effective time-lapse, or 4D, processing seeks to extract the 4D signature with minimal background noise to help understand reservoir behavior in the production phase and to optimize producer and injector well placement. Nonrepeatability of source and sensor positions in the presence of overburden heterogeneity limits our ability to repeat seismic data and to deliver 4D signals with low background noise levels. To compensate for imperfect receiver repositioning, wavefield-regularization techniques can enable wavefield matching on a grid common to both data vintages. Often there is a trade-off between reducing the receiver-positioning mismatch and crossline interpolation error from wavefield spatial aliasing. Through the use of towed multisensor marine seismic streamers that record collocated pressure (P) and acceleration measurements (Y and Z) and the application of a matching-pursuit interpolation technique, a 3D dealiased, reconstructed, and deghosted pressure wavefield can be obtained on a densely sampled grid that permits wavefield matching to prior positions in a highly effective way. From analysis on field multisensor streamer data, implications for time-lapse seismic and repeatability are investigated.

Strong noise attenuation method based on the multiuser kurtosis criterion

The strong noise produced by the leakage of electricity from marine seismic streamers is often received with seismic signals during marine seismic exploration. Traditional denoising methods show unsatisfactory effects when eliminating strong noise of this kind. Assuming that the strong noise signals have the same statistical properties, a blind source separation (BSS) algorithm is proposed in this paper that results in a new denoising algorithm based on the constrained multi-user kurtosis (MUK) optimization criterion. This method can separate strong noise that shares the same statistical properties as the seismic data records and then eliminate them. Theoretical and field data processing all show that the denoising algorithm, based on multi-user kurtosis optimization criterion, is valid for eliminating the strong noise which is produced by the leakage of electricity from the marine seismic streamer so as to preserve more effective signals and increase the signal-noise ratio. This method is feasible and widely applicable.

Optimized deghosting of over/under towed-streamer data in the presence of noise

Seismic exploration is widely used to locate geologic formations for hydrocarbon accumulations. In a typical marine seismic survey, one or more marine seismic streamers are towed behind a survey vessel. As the streamers are towed, acoustic signals, commonly referred to as “shots,” are produced by the seismic source. These travel down through the water column into strata beneath the water bottom surface, where they are reflected from the various geologic formations and travel back to the sea surface. One well-known marine seismic problem is that these upgoing waves are then reflected with inverted polarity at the sea surface because of the air/water interface. Hence, the sensors in the seismic streamer cable record not only the desired wavefield (i.e., the upgoing wave-reflected signal from various subterranean geologic formations), but also their reflections from the sea surface (the downgoing wave). The undesired downgoing reflected signal is known as the “receiver ghost.” Depending on the incidence angl...

Velocity images from stacking depth-slowness seismic wavefields

We present synthetic and real data examples processed using a depth imaging method for long-offset multichannel seismic data via the intercept-time-slowness (τ–p) domain. The refracted and reflected information contained in the wavefield is processed simultaneously. Our scheme uses common midpoint data that is transformed to the τ–p domain and mapped to the depth-slowness (z–p) domain using a downward continuation algorithm. The velocity function for downward continuation may be obtained iteratively from the diving ray trajectory within the slowness-depth wavefield or estimated using an independent method. Horizontal events within the z–p wavefield are isolated by applying a mute function corresponding to the downward continuation velocity function in the z–p domain. Stacking the resulting wavefield gives an image trace that may be superimposed on the velocity function to form a velocity image. Following testing on synthetic data the method is applied to two long-offset marine seismic streamer data sets with offsets up to 18 km, from the northeast Atlantic margin. These examples demonstrate the potential of the method to obtain velocity images in difficult geological locations, where conventional processing has been less successful.

Filling the gap: integrating nodes and streamer data for geophysical monitoring

E. Ceragioli, A. Kabbej, and A. Gonzalez Carballo of Total, and D. Marin of CGG, discuss how sparse distribution of seabed node receivers can complement conventional marine seismic streamer technology in the surveying of sensitive or obstructed targets with an example from an ultra deep water oil and gas field project.

Acoustic emitters for use in marine seismic surveying

An acoustic emitter for coupling in series in a marine seismic streamer is provided with an annular housing and an annular piezoelectric emitting element positioned coaxially within the housing. This form of construction permits the electrical or electro-optical transmission line which normally runs along the axis of the streamer to pass through the centre of the emitting element, while also permitting the emitter to be spooled with the streamer.

Two-dimensional full wavefield inversion of wide-aperture marine seismic streamer data

Summary A 2-D full wavefield inversion method is presented for the processing of wide-aperture data. The diversity of information contained within such datasets may be handled in a complete manner by first matching the traveltimes of the main events and then progressing to waveform fitting of the data through explicit full wavefield modelling. Our wavefield inversion scheme is based upon a finite difference solution of the 2-D elastic wave equation in the time distance domain. The strength of adopting such an approach is the ability to generate all possible wave types within a given 2-D model (multiples, converted waves, etc.) and thus to simulate and accurately model complex seismic wavefields. The aim of the inversion is to find the 2-D P-wave velocity model that minimizes the least squared difference between the observed and synthetic data across the full range of offsets. Following extensive testing on synthetic data, the wavefield inversion scheme has been applied to wide-aperture real marine seismic streamer datasets. We present results from the synthetic testing and the wavefield inversion of wide-aperture real data out to 12 km offset that was recorded on a single streamer. Even though current computational restrictions allow only a small subsection of the data to be analysed, these examples demonstrate the potential value of wide-aperture 2-D full wavefield inversion.

Modelling and Control of Towed Marine Seismic Streamer Cables

Summary Full-scale measurement data have revealed that slowly varying fluctuations in the course of survey vessels performing marine seismic data acquisition with towed recording (streamer) cables are capable of forcing the in-sea hardware in longitudinal and transverse directions. This may give rise to undesired low-frequency oscillations in the depth of streamer cables. The interaction between the transverse and longitudinal motions takes place at the location of the depth-control devices that are mounted along the streamers. A quasi-static model that describes the low-frequency dynamics of streamer cables is proposed for the purpose of controller design and analysis. The simulation study showed that the overall depth-control performance is sensitive to appropriate tuning of controller gains, selection of sampling period and application of dead bands. A successful depth control will rely on the number and lift capability of the mounted depth-control devices.

Cable strum self-noise cancellation for sonar towed arrays

Nonacoustic self-noise observed on marine seismic streamers and towed sonar arrays represents a serious problem for acoustic source detection at low frequency. Towed array self-noise, also known as cable strum, consists of mechanical vibrations induced by vortex shedding. Transverse vibrations in the array body subject each hydrophone pressure head to local accelerations. The resultant acoustic response can be several orders of magnitude stronger than the water-borne acoustic signals of interest. In this paper, a beamspace, time-domain adaptive signal processing architecture for the coherent rejection of broadband nonacoustic self-noise is presented. The approach is based on the recognition that most vibrational modes of a towed array propagate at phase speeds substantially less than those of acoustic signals in the water column. This property supports the formation of a signal-free, strum reference using the same sensor that samples the acoustic data. The approach removes the need for additional measurement channels, such as accelerometers or strain gauges, to independently sense the undesirable distortions introduced by cable strumming. The phenomenology underlying flow-induced self-noise for towed arrays is discussed and characterized using k-w analysis. An overview of the method is presented and cancellation performance is demonstrated using snapshots of passive sonar towed array data. [Work sponsored by the Department of the Navy, under Air Force Contract F19628-95-C-0002. Opinions, interpretations, conclusions, and recommendations are those of the author and are not necessarily endorsed by the U.S. Air Force.]