Increased resolution of seismic data from a dual‐sensor streamer cable

Carlson, David; Söllner, Walter; Tabti, H.; Brox, Eli; Widmaier, M.

doi:10.1190/1.2792572

Cited by 71 publications

(54 citation statements)

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“…Low-frequency seismic: the next revolution in resolution Figure 4 illustrates the ultra-low frequency response of the ghost function (Carlson et al, 2007). The phenomenon is comparable on both the source and receiver sides of any towed streamer survey.…”

Section: Appea Journal 2014-71mentioning

confidence: 99%

“…Figure 7 shows dual-sensor streamer data acquired above the Jotun gas field in the Norwegian North Sea. Wavefield separation processing (Carlson et al, 2007) removed the receiverside ghost effects, increasing the ultra-low frequency amplitude content by an additional octave, while also increasing the high-frequency content. A conventional source array was used, and no effort was made in processing to address the sourceside ghost effects.…”

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confidence: 99%

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Low-frequency seismic: the next revolution in resolution

Long

Reiser

2014

The APPEA Journal

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Ultra-low seismic frequencies less than about 7 Hz cannot be produced by conventional air gun arrays, for any configuration and for any towing depth. There is a profound difference between improving low-frequency recovery by removing source and receiver ghosts (achievable) and improving lowfrequency injection on the source side (an unrealised dream).If 1-7 Hz amplitudes could be usefully injected into the earth, it would be possible to facilitate much sharper seismic representation of geological contacts and internal features, and seismic inversion would yield robust and precise predictions of reservoir properties-without well control. The net result is fewer exploration and appraisal wells, greatly reduced exploration and development risks, and optimised recoverable reserves.Furthermore, an emerging seismic pursuit known as full waveform inversion (FWI) makes the bold promise that raw seismic field gathers can be directly used to invert for the highest achievable velocity models, almost without any human intervention. These models will bypass the traditional lack of low-frequency information in band-limited seismic data, and facilitate the aforementioned ambition of seismic inversion without well control. FWI, however, is confronted by the paradox that ultra-low-frequency seismic gathers are the necessary input for stable results. This paper describes new technologies that may enable the injection of strong 2-7 Hz amplitudes into the earth, and explains in simple terms how FWI can already be pursued as a robust complement to the prediction of accurate reservoir properties.The low-frequency revolution is already here. KEYWORDSLow-frequency, ghosts, deghosting, dual-sensor, seismic inversion, FWI, reservoir characterisation, seismic. INTRODUCTIONConventional air gun source arrays used for towed streamer (marine) seismic surveys cannot produce significant amplitudes below about 7 Hz. This 0-7 Hz range will be referred to as 'ultralow frequencies' . Although it may be counterintuitive, ultra-low frequency amplitudes can greatly improve vertical (temporal) seismic resolution, as demonstrated in Figure 1. Assuming that equal amplitudes are recovered in processing for all frequencies of relevance, additional low-frequency amplitudes will significantly attenuate sidelobe amplitudes on the zero phase wavelet representing elastic impedance boundaries in the earth. Note also in Figure 1 how additional low-frequency amplitudes do not affect the width of the central event. Overall, the interference between neighbouring reflection events in vertical columns of thin stratified layers will be minimised, thus optimising vertical resolution.Ultra-low frequency amplitudes are also critical for quantitatively precise estimation of elastic reservoir properties, which will be discussed later. Figure 2 is a comparison of two-dimensional towed streamer results over the Møre Margin area of the Norwegian North Sea. Note how the additional low-frequency amplitudes recovered in the ghost-free data have contributed to reduced sidel...

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Section: Appea Journal 2014-71mentioning

confidence: 99%

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confidence: 99%

Low-frequency seismic: the next revolution in resolution

Long

Reiser

2014

The APPEA Journal

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“…These new technologies include dual-component and multicomponent streamers (Carlson, 2007;van Manen et al, 2012;Mellier et al, 2014). Directional information can be included in data acquired with these new types of hardware and the recorded wavefield can therefore be decomposed into upgoing and downgoing wavefields.…”

Section: Introductionmentioning

confidence: 99%

A low-frequency deghosting method: Analysis and numerical tests

2017

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The low-frequency component of seismic data can be beneficial for several reasons: improved signal penetration into the earth, enhanced resolution, and better constrained inversion results. We have developed a detailed analysis of a deghosting solution for the low-frequency spectrum of marine seismic pressure data. The advantages of this low-frequency deghosting method are: (1) it can be applied in the spatial domain, (2) it is applicable for horizontal streamers and for streamers with a mild depth variation, and (3) it is a fast-track solution that can be used flexibly as a preprocessing, or premigration step. The disadvantages of this method are: (1) it is an approximation to the full-deghosting operator and cannot infill the ghost notches of the spectrum, except near 0 Hz, and (2) it has decreasing effectiveness with a larger source/receiver depth. Numerical tests on the synthetic and field data sets indicate that this method is promising in deghosting data, up to at least half the frequency of the first nonzero ghost notch.

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“…Additionally, Hicks et al (2014) demonstrate that advanced processing of flat streamer data could reveal results similar to advanced processing of a variable depth streamer. On the other hand, multicomponent receivers are used to measure pressure and particle velocity (Carlson et al, 2007) at the same depth. Using proper processing techniques, both methods reduce the notches in the frequency spectrum that are related to the ghost reflections from the surface (Ikelle and Amundsen, 2005).…”

Section: Introductionmentioning

confidence: 99%

Low-frequency acoustic signal created by rising air-gun bubble

Wehner

Landrø

2017

GEOPHYSICS

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In the seismic industry, there is increasing interest in generating and recording low frequencies, which leads to better data quality and can be important for full-waveform inversion. The air gun is a seismic source with a signal that consists of the (1) main impulse, (2) oscillating bubble, and (3) rising of this air bubble. However, there has been little investigation of the third characteristic. We have studied a low-frequency signal that could be created by the rising air bubble and find the contribution to the low-frequency content in seismic acquisition. We use a simple theory and modeling of rising spheres in water and compute the acoustic signal created by this effect. We conduct tank and field experiments with a submerged buoy that is released from different depths and record the acoustic signal with hydrophones along the rising path. The experiments simulate the signal from the rising bubble separated from the other two effects (1 and 2). Furthermore, we use data recorded below a single air gun fired at different depths to investigate if we can observe the proposed signal. We find that the rising bubble creates a low-frequency signal. Compared with the main impulse and the oscillating bubble effect of an air-gun signal, the contribution of the rising bubble is weak, on the order of 1/900 depending on the bubble size. By using large air-gun arrays tuned to create one big bubble, the contribution of the signal can be increased. The enhanced signal can be important for deep targets or basin exploration because the low-frequency signal is less attenuated.

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Increased resolution of seismic data from a dual‐sensor streamer cable

Cited by 71 publications

References 1 publication

Low-frequency seismic: the next revolution in resolution

Low-frequency seismic: the next revolution in resolution

A low-frequency deghosting method: Analysis and numerical tests

Low-frequency acoustic signal created by rising air-gun bubble

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