March 2023

A discussion note on “Using ‘Noise-Corrected OVT Fold’ to optimise land seismic acquisition risk, costs, and quality” by C. Stork published in First Break, January 2023 was added to this website. In the note I discuss the deviant use of ’Offset Vector Tiles’ in the paper. Next the example given of shot records with much noise is not representative according to my analysis. Then there is a discrepancy between modern day dense sampling and the main survey design serving as an example of the technique of noise-corrected fold. This is followed by a few words on ‘independent fold’ and some remarks about the conclusions.

The note can be found in Discussions.

December 2021

The paper “Compensating missing source points” with subtitle “Minimizing loss of coverage in 3D seismic surveys for areas where sources cannot be deployed, yet geophones may be planted” was published in the CSEG Recorder.

See Publications for a link to the paper.

May 2020

The paper “Are carpet geometries the way to go?” is published in the May issue of First Break. Here follows the abstract:

In the recent literature the use of carpet geometries (usually with 50 x 50-m source sampling) is being defended and recommended on the basis of its high trace density that produces superior quality compared to older techniques. However, trace density is not the best criterion to judge the quality of an acquisition geometry. Earlier model studies show that geometries with the same trace density may show very different quality, with the geometry with the smallest binsize being the best, because it allows better suppression of shot-generated noise in the basic subsets of the geometry. However, for land data acquisition it is too time-consuming and too expensive to use a carpet of sources that is dense enough to create well-sampled basic subsets. Orthogonal geometry does allow for small enough binsizes while being equally affordable as carpet geometries for which highly efficient acquisition techniques have been developed, but which lack a sufficiently small binsize.

See Publications for a link to the paper.

February 2020

At the end of this month 3DSymSam – Geophysical Advice is discontinued. No advice and no courses anymore. Yet, from time to time discussions on geophysics may appear on this website and discussions via e-mail are most welcome.

November 2017

Added a recent Comment paper published in Geophysics to the list of Publications.

Added a discussion of a paper by Cooper et al in the CSEG Recorder of September 2017.

July 2016: Brick geometry revisited

Brick geometry was quite popular in the early days of land 3D seismic data, especially because of its small Largest Minimum Offset (LMOS) as compared to orthogonal geometry with continuously sampled shot lines. Narrow brick geometry also had a better stack response than narrow orthogonal. Slanted geometry has a similar LMOS advantage and does not suffer from discontinuously sampled shot lines.
Brick geometry revisited – with a slant” makes a comparison of orthogonal, slanted and brick geometry with equivalent parameters (same station intervals, same line intervals and same maximum offsets).
This paper is a useful read for every geophysicist who wants to get a better understanding of spatial continuity and its effect on imaging. It also shows how arranging shot lines differently can lead to different LMOS.

March 2016

This website was changed to some extent. More importantly: A new online version of the Survey Design Wizard (formerly called Acquisition Design Wizard) is now available.