A proven method for acquiring highly repeatable towed streamer seismic data

Geophysics ◽  
2003 ◽  
Vol 68 (4) ◽  
pp. 1303-1309 ◽  
Author(s):  
Ola Eiken ◽  
Geir Ultveit Haugen ◽  
Michel Schonewille ◽  
Adri Duijndam
Keyword(s):  
Seismic Data ◽  
Time Lag ◽  
High Sensitivity ◽  
Seismic Properties ◽  
The North ◽  
Seismic Reservoir ◽  
The North Sea ◽  
Marine Seismic ◽  
Streamer Data ◽  
Proven Method

Seismic reservoir monitoring has become an important tool in the management of many fields. Monitoring subtle changes in the seismic properties of a reservoir caused by production places strong demands on seismic repeatability. A lack of repeatability limits how frequently reservoir changes can be monitored or the applicability of seismic monitoring at all. In this paper we show that towing many streamers with narrow separation, combined with cross‐line interpolation of data onto predefined sail lines, can give highly repeatable marine seismic data. Results from two controlled zero time lag monitoring experiments in the North Sea demonstrate high sensitivity to changing water level and variations in lateral positions. After corrections by deterministic tidal time shifts and spatial interpolation of the irregularly sampled streamer data, relative rms difference amplitude levels are as low as 12% for a deep, structurally complex field and as low as 6% for a shallow, structurally simple field. Reducing the degree of nonrepeatability to as low as 6% to 12% allows monitoring of smaller reflectivity changes. In terms of reservoir management this has three important benefits: (1) reservoirs with small seismic changes resulting from production can be monitored, (2) reservoirs with large seismic changes can be monitored more frequently, and (3) monitoring data can be used more quantitatively.

Attenuation of free-surface multiples by up/down deconvolution for marine towed-streamer data

Geophysics ◽  
2011 ◽  
Vol 76 (6) ◽  
pp. V129-V138 ◽  
Author(s):  
Mariusz Majdański ◽  
Clément Kostov ◽  
Ed Kragh ◽  
Ian Moore ◽  
Mark Thompson ◽  
...  
Keyword(s):  
Free Surface ◽  
Field Data ◽  
Near Field ◽  
Synthetic Data ◽  
Ocean Bottom ◽  
The North ◽  
The North Sea ◽  
Marine Seismic ◽  
Streamer Data ◽  
Multiple Elimination

Free-surface-related multiples in marine seismic data are commonly attenuated using adaptive subtraction of the predicted multiple energy. An alternative method, based on deconvolution of the upgoing wavefield by the downgoing wavefield, was previously applied to ocean-bottom data. We apply the deconvolution method to towed-streamer data acquired in an over/under configuration. We also use direct arrival deconvolution that results in source wavelet designature only, as a benchmark to verify the full multiple deconvolution result. Detailed synthetic data analysis, including sensitivity tests, explains each data processing step and its effects on the final result. We then apply this verified preprocessing sequence to field data from the Kristin area of the North Sea, with a focus on the direct arrival prediction using the near-field hydrophone method. Prestack evaluation of the results shows that the method applied to the field data provides designature, source-side deghosting, and attenuation of multiples. We show comparable stacked results from our method and from 2D iterative surface-related multiple elimination. The workflow has the benefit that it does not require an adaptive subtraction step or iterative application. However, an accurate direct arrival prediction is essential for the successful application of the method. This prediction is obtained using near-field hydrophone measurements that can be recorded with some commercial acquisition systems.

Large-scale siliciclastic input during the Paleocene-Eocene Thermal Maximum in the North Sea Basin

2021 ◽  
Author(s):  
Simin Jin ◽  
David Kemp ◽  
David Jolley ◽  
Manuel Vieira ◽  
Chunju Huang
Keyword(s):  
Carbon Isotope ◽  
North Sea ◽  
Climate Warming ◽  
Large Scale ◽  
Time Lag ◽  
Sediment Supply ◽  
Deep Time ◽  
The North ◽  
Thermal Maximum ◽  
The North Sea

<p>The Paleocene-Eocene Thermal Maximum (PETM, ~56 Ma) was the most marked climate warming event of the Cenozoic, and a potentially useful deep time analogue for understanding environmental responses to anthropogenic carbon emissions and associated warming. The response of sedimentary systems to the large-scale climate changes of the PETM are, however, still uncertain. Here, we present an extremely thick (~140 m) record of the PETM in cores from a well in the North Sea, offshore UK. In this well, a thick Paleocene-Eocene interval is developed owing to uplift of the East Shetland Platform in the late Paleocene. Carbon isotope data through this well, coupled with detailed sedimentological analysis, show that the PETM interval is contemporaneous with >200 sandstone turbidites layers. Mud deposition without turbidites dominated sedimentation below and above the PETM. These observations support previous work from other localities highlighting how climate warming during the PETM likely drove substantial changes in hydrological cycling, erosion and sediment supply. Spectral analysis of turbidite recurrence in the PETM interval suggests that the abundance of turbidites was modulated in part by ~21 kyr astronomical precession climate cycles, further emphasizing a potential climatic control on turbidite sedimentation. In detail, we note a kiloyear-scale time lag between onset of the PETM carbon isotope excursion and the appearance of turbidites in the succession, highlighting a delay between PETM carbon release and warming and the basin-wide response in sediment supply.</p>

Imaging the sea surface using a dual-sensor towed streamer

Geophysics ◽  
2010 ◽  
Vol 75 (6) ◽  
pp. V111-V118 ◽  
Author(s):  
Okwudili Orji ◽  
Walter Söllner ◽  
Leiv Jacob Gelius
Keyword(s):  
Seismic Data ◽  
Time Window ◽  
Finite Difference Methods ◽  
Surface Profile ◽  
Sea Surface ◽  
Data Sets ◽  
The North ◽  
Dual Sensor ◽  
The North Sea ◽  
Time Invariant

Sea-surface profile and reflection coefficient estimates are vital input parameters to various seismic data processing applications. The common assumption of a flat sea surface when processing seismic data can lead to misinterpretations and mislocations of events. A new method of imaging the sea surface from decomposed wavefields has been developed. Wavefield separation is applied to the data acquired by a towed dual-sensor streamer containing collocated pressure and vertical particle velocity sensors to obtain upgoing and downgoing wavefields of the related sensors. Time-gated upgoing and downgoing wavefields corresponding to a given sensor are then extrapolated to the sea surface where an imaging condition is applied so that the time-invariant shape of the sea surface can be recovered. By sliding the data time-window, the temporal changes of the sea surface can be correspondingly estimated. Ray tracing and finite-difference methods were used to generate different controlled data sets used in this feasibility study to demonstrate the imaging principle and to test the image accuracy. The method was also tested on a first field data example of a marginal weather line from the North Sea.

Quaternary evolution of the northern North Sea

2020 ◽  
Author(s):  
Christine Batchelor ◽  
Dag Ottesen ◽  
Benjamin Bellwald ◽  
Sverre Planke ◽  
Helge Løseth ◽  
...  
Keyword(s):  
North Sea ◽  
Seismic Data ◽  
3D Seismic ◽  
Quaternary Sediments ◽  
The North ◽  
The North Sea ◽  
Data Coverage ◽  
Northern North Sea ◽  
2D And 3D ◽  
3D Seismic Data

<p>The North Sea has arguably the most extensive geophysical data coverage of any glacier-influenced sedimentary regime on Earth, enabling detailed investigation of the thick (up to 1 km) sequence of Quaternary sediments that is preserved within the North Sea Basin. At the start of the Quaternary, the bathymetry of the northern North Sea was dominated by a deep depression that provided accommodation for sediment input from the Norwegian mainland and the East Shetland Platform. Here we use an extensive database of 2D and 3D seismic data to investigate the geological development of the northern North Sea through the Quaternary.</p><p>Three main sedimentary processes were dominant within the northern North Sea during the early Quaternary: 1) the delivery and associated basinward transfer of glacier-derived sediments from an ice mass centred over mainland Norway; 2) the delivery of fluvio-deltaic sediments from the East Shetland Platform; and 3) contourite deposition and the reworking of sediments by contour currents. The infilling of the North Sea Basin during the early Quaternary increased the width and reduced the water depth of the continental shelf, facilitating the initiation of the Norwegian Channel Ice Stream.</p>

High-resolution reservoir characterization by an acoustic impedance inversion of a Tertiary deltaic clinoform system in the North Sea

Geophysics ◽  
2010 ◽  
Vol 75 (6) ◽  
pp. O57-O67 ◽  
Author(s):  
Daria Tetyukhina ◽  
Lucas J. van Vliet ◽  
Stefan M. Luthi ◽  
Kees Wapenaar
Keyword(s):  
North Sea ◽  
Seismic Data ◽  
Reservoir Characterization ◽  
Structural Information ◽  
Sampling Rate ◽  
Seismic Inversion ◽  
Acoustic Properties ◽  
The North ◽  
The North Sea ◽  
Well Data

Fluvio-deltaic sedimentary systems are of great interest for explorationists because they can form prolific hydrocarbon plays. However, they are also among the most complex and heterogeneous ones encountered in the subsurface, and potential reservoir units are often close to or below seismic resolution. For seismic inversion, it is therefore important to integrate the seismic data with higher resolution constraints obtained from well logs, whereby not only the acoustic properties are used but also the detailed layering characteristics. We have applied two inversion approaches for poststack, time-migrated seismic data to a clinoform sequence in the North Sea. Both methods are recursive trace-based techniques that use well data as a priori constraints but differ in the way they incorporate structural information. One method uses a discrete layer model from the well that is propagated laterally along the clinoform layers, which are modeled as sigmoids. The second method uses a constant sampling rate from the well data and uses horizontal and vertical regularization parameters for lateral propagation. The first method has a low level of parameterization embedded in a geologic framework and is computationally fast. The second method has a much higher degree of parameterization but is flexible enough to detect deviations in the geologic settings of the reservoir; however, there is no explicit geologic significance and the method is computationally much less efficient. Forward seismic modeling of the two inversion results indicates a good match of both methods with the actual seismic data.

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