A note on variable line intervals in orthogonal geometry is added under “Discussions”.
From time to time developments in the world of seismic data acquisition that are not covered in “3D seismic survey design” may be included under the tab “Book supplements”.
Added a discussion note on “unique fold”. It explains why this concept is not useful for guiding the choice of survey design parameters.
December 2012 – Some acquisition highlights of SEG 2012
Apart from the 3DSymSam highlight mentioned under November 2012 below, a few notes on acquisition can be found in highlights SEG 2012.
November 2012 – The second edition of “3D seismic survey design” is now available at the SEG BookMart
Since the first edition of 3D seismic survey design appeared in 2002, seismic data acquisition has seen many changes, most of which have been captured in this second edition. The book by Gijs Vermeer describes in detail the properties of 3D acquisition geometries and shows how these properties naturally lead to the 3D symmetric sampling approach to 3D survey design. Many examples from the literature are used to illustrate good and less good choices of acquisition parameters. The link between survey parameters and noise suppression as well as imaging is an intrinsic part of the contents. This book should be of great interest to the designer of 3D seismic surveys, but also to every geophysicist who uses 3D seismic data to retrieve accurate information on the properties of the subsurface.
February 2009 – Acquisition Design Wizard
A web version of 3DSymSam’s Acquisition Design Wizard was installed on this website.
July 2008 (revised January 2009) – Wide-azimuth towed streamer data acquisition and simultaneous sources
Wide-azimuth towed streamer data acquisition is becoming quite popular, albeit very expensive. To increase efficiency it has been proposed to use simultaneous sources. This website now includes a paper that argues that WATS configurations with parallel source and receiver tracks cannot benefit much from simultaneous sources. Instead a zigzag WATS is proposed.
Here follows some text from the introduction
“This paper starts with the description of some characteristics of a typical WATS configuration. Next it is argued that this configuration can be viewed not only as parallel geometry but also as areal geometry, because a major objective of WATS is to acquire 3D shot gathers. If viewed as areal geometry, the inline source sampling is often quite dense, whereas the crossline source sampling is often quite coarse. Other aspects, such as binsize, edge effects and feathering, are discussed as well in the light of what would be an ideal areal geometry. Next, I argue that simultaneous sources will only help to reduce acquisition cost and time of areal WATS configurations in case more than about 8 sources are used.
Geometries that would benefit from simultaneous sources are those that require dense sampling of sources along the source lines. Narrow-azimuth geometry and zigzag WATS are discussed as examples of such geometries. This paper is rounded off with a discussion of pros and cons of zigzag WATS configurations.”
Summary and Full paper
From time to time it is argued that cable-free systems would bring freedom in the choice of receiver station locations. To learn how this is viewed in the light of 3D symmetric sampling requirements, read the note “Noise suppression, prestack imaging and freedom_of_choice”.
NMO stretch has an effect on the resolution of final stacked and migrated data that depends on the mix of offsets contributing to the final product. For the same range of absolute offsets, 2D data are less affected by resolution loss than 3D data. This is discussed in the note “NMO stretch for P- and C-waves and its link to resolution, AVO and mute offset”.
The note also discusses the link between AVO-requirements and NMO stretch, the link between mute offset as a function of depth and NMO stretch, and the note describes NMO stretch for C-waves.
Wide-azimuth towed streamer (WATS) acquisition is a new technique with potential for better subsalt imaging. It is a highly expensive technique, because it involves traversing the survey area multiple times with varying crossline offsets between streamer vessel and source vessels. The expense of the technique has led to undesirable corner cutting such as acquiring data in only two of the four source-receiver azimuth quadrants. In some papers this cost-saving method has been justified on basis of reciprocity: reciprocity would make data acquired in opposite quadrants redundant.
The paper “Reciprocal offset-vector tiles in various acquisition geometries” presented at the 2007 SEG Conference held in San Antonio, Texas, argues that in sparse geometries data acquired in opposite quadrants are complementary rather than redundant.
The paper Processing orthogonal geometry – what is missing? tries to generate interest in geometry-oriented processing techniques specifically for orthogonal geometry. It was presented at the 75th SEG Conference in Houston.
In the discussion on single sensors versus arrays arrays tend to get more beatings than they deserve. A discussion defending short arrays can now be read on this website.
The October 2004 issue of The Leading Edge featured a large number of interesting papers on Seismic Survey Design. Some comments on two of these papers have now been included.
The number of channels needed in an ideal acquisition geometry has been the subject of some debate, especially in connection with the advent of single-point acquisition (Q-technology), MEMS-type sensors, and the Infinite Telemetry system of Vibtech. The paper An ambitious land geometryy contributes to the debate. It was published in the October 2004 issue of The Leading Edge.
The Recorder, the journal of the Canadian SEG, features a new series called “Expert Answers”. The April 2004 issue includes expert answers by Gijs Vermeer and Mike Galbraith on 3D seismic survey design. In the May 2004 issue Tessman and Cooper discuss digital geophones and in the June 2004 issue various experts discuss marine data acquisition. The April 2004 issue of the Recorder also features “A comparison of two different approaches to 3D seismic survey design” by Gijs J.O. Vermeer. All papers can be downloaded from the CSEG website.
The book “3-D seismic survey design” contains a CD-Rom with some design software, including a spreadsheet for survey design optimization. It also contains a 4-page paper to explain the technique. A more elaborate paper has now been published in the October 2003 issue of The Leading Edge.
In the November/December issue of Geophysics the paper “Analyzing the effectiveness of receiver arrays for multicomponent seismic exploration” by Hoffe et al. was published. See for a short discussion Comments to Hoffe et al. See for the reply by Hoffe et al. the September/October 2003 issue of Geophysics.
The note Conventional wisdom was published earlier on this website. This note has now been expanded into an abstract for presentation at the 2003 SEG Conference in Dallas. The paper A comparison of two different approaches to 3D seismic survey design can be downloaded.
In the November/December issue of Geophysics a paper by Gibson and Tzimeas was published. It compares the resolution of a complex medium for different acquisition geometries. See for a discussion Comments to Gibson and Tzimeas paper. Their interesting reply has been published in Geophysics, 2004, 619-623. The reply now contains resolution comparisons for data with about the same range of midpoints.