Peter Aaron

An exploration‐scale wide azimuth towed streamer case study

Wide azimuth towed streamer surveys (WATS) have recently proven quite successful at improving illumination and attenuating multiple energy in difficult subsalt imaging environments. However, they present new challenges in terms of survey design, acquisition and processing methodology and operations. In particular, the sheer volume of data acquired requires pragmatic approaches to data processing. A 2007 deepwater Gulf of Mexico WATS survey of exploration scale (10,000 km2) illustrates these challenges and demonstrates the need for increased fold and cross-line offset.

Enhanced demultiple by 3D SRME using dual-sensor measurements

In recent years, dual-sensor recording has been introduced to marine seismic acquisition with reported benefits such as the increased bandwidth of the acquired seismic signal, improved signal-to-noise ratios due to deep-tow streamers, and operational efficiency due to an increased weather window.

A Robust Strategy for Processing 3D Dual-sensor Towed Streamer Data

A dual-sensor streamer records not only the pressure field but additionally the vertical component of the particle velocity field. Properly matched records may be used to separate the total wavefield into up- and down-going parts. In this paper, we presen

Data regularization for 3-D SRME: A comparison of methods

Summary This paper discusses and compares different strategies for data regularization prior to the application of 3-D SRME. It is shown that synthetic analysis can be utilized to determine whether azimuth corrections are needed during data regularization. It is shown that only in certain instances this is needed, depending on the azimuth between the dipping reflectors and the acquisition direction. Also, the reflector dips, offset ranges and the reflectors depths are important. For geometries where azimuth corrections are needed, a comparison is made between two well-known solutions: Forward DMO followed by inverse DMO (DMO-DMO -1 ) regularization, and Fourier regularization with azimuth correction. It is shown that the latter shows better performance in terms of amplitude fidelity, as well as dealing with practical issues such as irregular sampling due to feathering of the streamers. Application of the Fourier regularization method to a field data set shows that the method is very capable of predicting complex 3-D multiples in the presence of multiple diffractions.

Simultaneous Sources: A Controlled Experiment On Different Source Configurations

The simultaneous firing of marine sources can provide a significant uplift in terms of acquisition efficiency. However, the seismic interference resulting from one or more “other” sources needs to be well understood and the appropriate processing techniques need to be investigated. This paper uses the well known BP Wide-Azimuth Towed Streamer (WATS) synthetic dataset to carry out a controlled investigation into the effect of additional noise in 3D surface-related multiple elimination (SRME), depth migration and source separation. Two different simultaneous source configurations are considered: a front and tail and a side by side survey design. Results show that the front/tail configuration gives naturally cleaner results after 3D SRME and migration, but some source separation should always be applied; 3D SRME or migration alone isn’t enough to suppress the additional noise.

Lessons Learned from the First Exploration WATS Data Processing

Previous to now, Wide Azimuth marine surveys have generally been organized along prospect development scale. This paper concerns a 2007 Deep Water Gulf of Mexico Wide Azimuth Towed Streamer (WATS) project executed on much larger exploration scale. The size of the data volumes and the challenges introduced by WATS acquisition geometries demand a pragmatic approach to processing the data. In this paper, data processing insights and results are presented which have been achieved to date. Comparisons between seismic images from initial results to legacy Narrow Azimuth Towed Streamer (NATS) are shown, as well as imaging utilizing various classes of acquired traces. Furthermore, significant experiences in applying processing technologies such as tomography and 3-D SRME are also reviewed.

Application of 3-D SRME And Multiple Diffraction Removal In the Makassar Straits, Indonesia.

It is recognized that 3-D related noise problems and multiple attenuation in particular can be benefit from currently non-standard acquisition techniques, like, for instance, multi-azimuth (Widmaier et al. 2002) and streamer overlap (van Borselen et al. 2005). However processing solutions are still required for historical and new standard marine acquisition datasets. Especially for the application of 3-D Surface Related Multiple Elimination (SRME), the issues of limited crossline sampling and aperture have to be addressed. A variety of methods for dealing with these issues have been proposed in the literature, which can be broadly categorized into a) a full wavefield interpolation or reconstruction, followed by a large number of 3-D inline convolutions to create a dense grid of multiple contributions (MCs) and finally summation in the crossline direction of those MCs (see, for instance, Baumstein and Hadidi, 2004), or b) calculation of 3-D inline convolutions to create MCs wherever possible using the existing data followed by sparse inversion in the crossline direction (van Dedem and Verschuur, 2002; Hokstad and Sollie, 2003). The hybrid approach described in van Borselen et al. (2005) consists of a more limited sailline regularisation and reconstruction in the crossline direction and sparse inversion of the subsequently increased number of crossline MCs. Major advantages are the reduced number of 3-D inline convolutions that need to be calculated compared to full reconstruction approaches, while with more MCs the sparse inversion becomes easier to parameterize and provides better results. This 3-D prediction approach is used in the current case study.

Dual-sensor Enhanced 3D Surface-related Multiple Elimination

In recent years dual-sensor recording has been introduced to marine seismic acquisition with reported benefits such as the increased band-width of the acquired seismic signal, improved signal-to-noise ratios due to deep-tow streamers, and operational efficiency due to an increased weather window. This abstract describes another advantage of dual-sensor measurements, namely the opportunity it provides to better predict and subtract surface-related multiples from marine seismic data compared to using conventional data acquisition. Using a dataset from offshore Greenland, it is demonstrated that dual-sensor acquisition leads to a more accurate set of predicted multiples with respect to phase and amplitudes. As a result, the adaptive subtraction of the multiples can be carried out in a more constrained and robust manner, leading to better multiple elimination and better primary preservation.

Simultaneous Source – Preprocessing and Imaging Challenges

This paper discusses a simultaneous source wide azimuth acquisition experiment which was performed in the Gulf of Mexico. Out of a total of 4 sources, two of them were fired simultaneously, with all firing times being randomized within a small window. Sta

True-azimuth Versus Zero-azimuth 3-D Multiple Prediction – Two Case Studies

The paper discusses two different strategies for data-driven 3-D multiple prediction in marine seismic data processing. A comparison is made between methods that make use of zero-azimuth assumptions, where multiples are generated for source and receiver p