Mitigation of the 3D Cross-line Acquisition Footprint Using Separated Wavefield Imaging of Dual-sensor Streamer Seismic

Long, Andrew; Lu, Shaoping; Whitmore, D.; LeGleut, Hui; Jones, Richard T.; Chemingui, Nizar; Farouki, Mazin

doi:10.3997/2214-4609.20130005

Cited by 5 publications

(3 citation statements)

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“…It has been demonstrated that the concept of virtual source imaging (Wapenaar et al, 2010) can be extended to multi-sensor streamer acquisition to utilize sea surface reflected downgoing wavefield energy that provides the missing near-surface information. Recent case studies (e.g., Long et al, 2013 andRønholt et al, 2014), demonstrate how separated wavefield imaging from dualsensor systems can be used to remove acquisition footprints and shallow coverage gaps that are evident if only the primary reflections are used ( Figure 5). The shallow overburden can not only be imaged seamlessly, but also complemented by AVO/AVA analysis facilitated by the virtual source concept.…”

Section: Improving Near-surface Imagingmentioning

confidence: 99%

Dual Sensor Towed Streamer: From Concept to Fleet-Wide Technology Platform

Widmaier¹,

Day²

2015

Proceedings

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discuss the lessons learnt from the roll out of dual-sensor technology in PGS' fleet.T he launch of the dual-sensor towed streamer technology in 2007 is seen by many in the industry as the most important milestone in marine seismic technology in the last decade. The introduction of the technology triggered a significant interest and demand for broader bandwidth seismic data and increased the industry-wide awareness of the geophysical benefits of such broadband data for both frontier exploration and production monitoring in mature basins. It also resulted in the rapid development of new acquisition and processing technology, both concerning the source and receiver side, as well as changes to seismic vessel design and equipment. The geophysical benefits of broadband data and the availability of up-and down-going wavefields as part of the dual-sensor deghosting methodology are now routinely exploited throughout the entire seismic value chain, including seismic imaging and reservoir characterization.After the first 2D dual-sensor survey in 2007, which was quickly followed by the first 3D acquisition commencing on New Year's Eve 2008, PGS has steadily converted its seismic fleet from hydrophone-only to dual-sensor streamers. The pace of the technology roll-out has been largely driven by the life-cycle of existing streamer inventory and the equipment needs for newly launched seismic vessels as part of an ongoing fleet renewal process. The fleet-wide roll-out of dual-sensor technology will finally be completed in the 4 th quarter of 2015 with the upgrade of the last Ramform vessel. Given the scale and complexity of replacing and industrializing a complete acquisition platform, there have naturally been significant lessons, some of which we will be sharing in this article. We will also discuss some of the acquisition and processing technologies that have been developed and/ or adapted in order to fully utilise this new marine seismic technology platform. Robust ghost removal for deeper streamer towTo be successful in today's challenging E&P environment, petroleum geoscientists must detect and properly image increasingly complex reservoirs by resolving the fine detail of ever smaller hydrocarbon accumulations. High quality seismic data plays a key role in this task and is of great significance in the effort to reduce overall E&P risk. The demands placed on modern seismic data are multifold, but critically the data needs to enable the identification and delineation of leads/prospects based on pre-stack seismic and to quantify key reservoir properties to increase the probability of successfully separating lithology-fluid facies. All of these goals must be achieved in 3D using all the dimensions of the seismic data, mainly pre-stack, and later on 4D (time-lapse). It has been well understood for some time that data richer in both low and high frequency information would form the optimum input for improved reservoir delineation and high-resolution imaging and that improvements in the signal-to-noise ratio of the recorded data ...

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Section: Improving Near-surface Imagingmentioning

confidence: 99%

Dual Sensor Towed Streamer: From Concept to Fleet-Wide Technology Platform

Widmaier¹,

Day²

2015

Proceedings

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“…It is this difference in polarity that facilitates proper wavefield separation. Figure 1 shows a shallow imaging example from a 3D dual-sensor towed streamer survey over the Tenggol Arch area in offshore Peninsular Malaysia (Long et al, 2013). Water depth is approximately 70 m. This survey was acquired in 2011 using a 12 x 4050 m dual-sensor streamer spread with 75 m separation and 15 m streamer depth.…”

Section: Seismic Imaging Of Shallow Anomalies With Dual-sensor Towed mentioning

confidence: 99%

“…By utilising broad-band dual sensor seismic data it is now possible to use the complete wave-field to image the overburden in great detail in complex geological settings. For example, Long et al (2013) and Rønholt et al (2014) presented shallow water case studies that illustrated how the free surface multiple reflections, i. e. down-going wave-field can be used to image the overburden, and remove the acquisition footprint that is evident if only the primary reflections are used. The fact that the 3D seismic acquisition footprint can be effectively eliminated, and that the shallow sub-surface can be imaged in great detail, opens up the possibility that exploration seismic data can be used to identify and interpret shallow anomalies with confidence.…”

Section: Introductionmentioning

confidence: 99%

Detection, Delineation and Characterization of Shallow Anomalies Using Dual Sensor Seismic and Towed Streamer EM data

McKay¹,

Widmaier²,

Bhuiyan³

et al. 2014

Proceedings

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Recent developments in broadband marine seismic and EM technology enables high-resolution imaging and improved characterisation of shallow anomalies. In particular, broad-band dual sensor seismic data enables separated wavefield imaging that produces high resolution images of the shallow sub-surface even when a wide 3D seismic spread is employed in shallow water. In addition, by using the full wavefield in, for example, full waveform inversion, shallow velocity variations associated with channels, pock-marks and gas-pockets can be imaged. By using a Towed Streamer EM system it is now possible to acquire Controlled Source Electromagnetic (CSEM) data simultaneously with seismic data using a single vessel. CSEM data enables the sub-surface resistivity to be determined, and the simultaneous acquisition enables CSEM data to be acquired efficiently, cost-effectively and early in the exploration cycle. By combining the high-resolution structural and velocity seismic images with images of sub-surface resistivity, it is possible to determine the origin, potential drilling hazard, and resource potential of shallow anomalies.

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Fast imaging with surface-related multiples by sparse inversion

Herrmann

2015

Geophysical Journal International

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In marine exploration seismology, surface-related multiples are usually treated as noise mainly because subsequent processing steps, such as migration velocity analysis and imaging, require multiple-free data. Failure to remove these wavefield components from the data may lead to erroneous estimates for migration velocity or result in strong coherent artifacts that interfere with the imaged reflectors. However, multiples can carry complementary information compared to primaries, as they interact with the free surface and are therefore exposed more to the subsurface. Recent work has shown that when processed correctly multiples can improve seismic illumination. Given a sufficiently accurate background velocity model and an estimate for the source signature, we propose a new and computationally efficient two-way wave-equation based linearized inversion procedure that produces accurate images of the subsurface from the total upgoing wavefield including surface-related multiples. Modelling of the surface-related multiples in the proposed method derives from the well-known surface-related multiple elimination method. We incur a minimal overhead from incorporating the multiples by having the wave-equation solver carry out 2 Tu and Herrmann the multiple predictions via the inclusion of an areal source instead of expensive dense matrix-matrix multiplications. By using subsampling techniques, we obtain high-quality true-amplitude least-squares migrated images at computational costs of roughly a single reverse-time migration with all the data. These images are virtually free of coherent artifacts from multiples. Proper inversion of the multiples would be computationally infeasible without using these techniques that significantly brings down the cost. By promoting sparsity in the curvelet domain and using rerandomization, out method gains improved robustness to errors in the background velocity model, and errors incurred in the linearization of the wave-equation with respect to the model. We demonstrate the superior performance of the proposed method compared to the conventional reverse-time migration using realistic synthetic examples.

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Mitigation of the 3D Cross-line Acquisition Footprint Using Separated Wavefield Imaging of Dual-sensor Streamer Seismic

Cited by 5 publications

References 5 publications

Dual Sensor Towed Streamer: From Concept to Fleet-Wide Technology Platform

Dual Sensor Towed Streamer: From Concept to Fleet-Wide Technology Platform

Detection, Delineation and Characterization of Shallow Anomalies Using Dual Sensor Seismic and Towed Streamer EM data

Fast imaging with surface-related multiples by sparse inversion

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