Alaska 2D land line 31-81

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Overview

This 2D land data, from the National Petroleum reserve Alaska, is provided by the U.S. Geological Survey. It is a short line with small statics. There is ground roll and noise bursts, but there is also good signal. Data includes unprocessed prestack data, final stack, and images of previous stack. Scripts for processing with Seismic Unix (su) are available. This is a good line to start experimenting with open data and su because there is a full processing sequence including data download, reformat, header loading, gain, prestack f-k filter, brute velocity estimation, brute stack, residual statics, final velocity analysis, final stack, and two types of post stack migration (phase shift and Kirchhoff migration). This 2D land data comes with executables for su release 43R1 on Linux, which is useful if su is not installed on your system.

How to obtain a copy of the data

The simplest way to obtain a copy of the data is via download; use the tar file with Seismic Unix processing scripts (from drop box or same thing from amazon) described below in the section "A tar file with Seismic Unix processing scripts". To access the U.S. Geological Survey data collected from 1974 until 1981 in the National Petroleum Reserve Alaska, click here. Search for line 31-81 to find SEG Y files of the raw field data and processed stack section. The observer's log, surveyer's log, and scanned image of the stack section are also available.

There are many other 2D lines available at this web site.

Terms of use

There are no usage constraints on this data. Users should credit the U.S. Geological Survey as the data source.

Seismic Unix processing scripts

Seismic Unix scripts to process 2D land lines

To access a general overview of the survey and example su results, click here. In addition to the general overview website, click here for a paper describing "how to process an internet downloadable 2D land line data set through a very basic processing sequence using Seismic Unix."

The paper, "Open Data/Open Source: Seismic Unix scripts to process a 2D land line," is also available here.

A tar file with Seismic Unix processing scripts

A copy seismic unix, and scripts to download and process Alaska line 31-81 can be obtained using these directions. There are also some presentations, a paper, and other support data in the tar file.

Please log onto a Linux computer, open the web browser, and go to: http://dl.dropbox.com/u/37269048/open_seismic_data/alaska31-81.tar.gz. The file should automatically download. Or (there have been issues reported in China), right click on: http://s3.amazonaws.com/open.source.geoscience/open_data/alaska/alaska31-81.tar.gz and then select Save Link As... Next, open a terminal window and type the following dialog:

cd
mkdir open_data
find . -name alaska31-81.tar.gz

On my computers it finds the file as Downloads/alaska31-81.tar.gz or /tmp/alaska31-81.tar.gz. Continue the dialog with:

mv ../Downloads/alaska31-81.tar.gz open_data
cd open_data
tar -xvf alaska31-81.tar.gz

This will untar the directory. When it completes, type:

cd alaska31-81
cat readme

Creating a reproducible document using Seismic Unix and Madagascar.

If the development or production version of Madagascar is installed, there should be a copy of the SConstruct file to process this line using Seismic Unix. Seismic Unix also needs to be installed. Creation of a reproducible document is also possible. Apply the processing with the following commands:

cd ${RSFSRC}/book/data/alaska/line31-81
scons view
scons lock
cd ..
scons read

External links

find literature about
Alaska 2D land line 31-81
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