Seismic Unix

History

Einar Kjartansson began writing what is now called SU (the SY package) in the late 1970s while still a graduate student at Jon Claerbout's Stanford Exploration Project (SEP). He continued to expand the package while he was a professor at the University of Utah in the early eighties. In 1984, during an extended visit to SEP Einar introduced SY to Shuki Ronen, then a graduate student at Stanford. Ronen further developed SY from 1984 to 1986. Other students at SEP started to use it and contributed code and ideas. SY was inspired by much other software developed at SEP and benefited from the foundations laid by Claerbout and many of his students; Rob Clayton, Stew Levin, Dave Hale, Jeff Thorson, Chuck Sword, and others who pioneered seismic processing on Unix in the seventies and early eighties.

In 1986, Shuki Ronen brought this work to the CWP at Colorado School of Mines during his one-year postdoctoral appointment there, Ronen aided Cohen in turning SU into a supportable and exportable product.

Chris Liner (homepage), while a student at the Center, contributed to many of the graphics codes used in the pre-workstation (i.e., graphics terminal) age of SU. Liner continues to promote the use of SU in his students' research at the University of Houston.

Craig Artley, now with the Landmark division of Halliburton, made major contributions to the graphics codes while still a student at CWP and continues to make significant contributions to the general package.

Dave Hale wrote several of the heavy lifting processing codes as well as most of the core scientific and graphics libraries.

John Stockwell's involvement with SU began in 1989. He was largely responsible for the Makefile in the package. He has been the main contact for the project since the first public release of SU in September 1992 (Release 17). After Jack Cohen's death in 1996, Stockwell assumed the role of principal investigator of the SU project and has since remained in that role. The number of lines of code have more than tripled in the 11 years.

There have been many contributors to SU over the past two decades.

Syntax

The Seismic Unix routines run under the Unix terminal, and can get maximum efficiency when using it with Bourne Shell (sh) or Bourne-again Shell (bash) scripting techniques.

Simple routines

Many of the programs run simply by a command on the terminal, for instance, to visualize a seismogram, as wiggle traces

or as an image plot

More elaborated routines

It is also possible, to use bash features to elaborate more complex processing structures:

In the example above Seismic Unix will create 100 seismograms in 100 different source positions

SU Data

Here will have an explanation of how SU data is, it's headers and how they are organized in a big SU file with more than one gather:

--header—data—header—data--...

SU Programs

Seismic Unix has many of the processes needed on the geophysical processing. It is possible to use it to manipulate and create your own seismograms, and also to convert them between the SU standard file and the industry standard, the SEG Y.

Here you can find a list of the programs that the SU package has, with a brief description and a link to its help page.

Data Compression

Discrete Cosine Transform

dctcomp Compression by Discrete Cosine Transformdctuncomp Discrete Cosine Transform Uncompression

Packing

supack1 Pack segy trace data into charssuunpack1 Unpack segy trace data from chars to floatssupack2 Pack segy trace data into 2 byte shortssuunpack2 Unpack segy trace data from shorts to floats

Wavelet Transforms

wpc1comp2 Compress a 2D seismic section trace-by-trace using Wavelet Packetswpc1uncomp2 Uncompress a 2D seismic section, which has been compressed using Wavelet Packetswpccompress Compress a 2D section using Wavelet Packetswpcuncompress Uncompress a 2D sectionwptcomp Compression by Wavelet Packet Compressionwptuncomp Uncompress WPT compressed datawtcomp Compression by Wavelet Transformwtuncomp Uncompression of WT compressed data

Editing, Sorting and Manipulation

Edit + Tools

suabshw Replace header key word by its absolute valuesuazimuth Compute trace AZIMUTH given the sx,sy,gx,gy header fields and set a user-specified header field to this valuesubset Select a SUBSET of the samples from a 3-dimensional filesuchw Change Header Word using one or two header word fieldssucountkey Count the number of unique values for a given keywordsuedit Examine segy diskfiles and edit headerssugethw Sugethw writes the values of the selected key wordssukill Zero out tracessunan remove NaNs & Infs from the input streamsuquantile display some quantiles or ranks of a data setsurange get max and min values for non-zero header entriessushw Set one or more Header Words using trace number, mod and integer divide to compute the header word values or input the header word values from a filesutab print non zero header values and data for non-graphic terminalssuwind window traces by key wordsuxedit examine segy diskfiles and edit headers

Sort

susort sort on any segy header keywordssusorty make a small 2-D common shot off-end data set in which the data show geometry values to help visualize data sorting

Manipulate

fcat fast cat with 1 read per filemaxdiff find absolute maximum difference in two segy data setssegyhdrmod replace the text header on a SEGY filesuaddnoise add noise to tracessucmp CoMPare two seismic data sets, returns 0 to the shell if the same and 1 if differentsudiff,susum,suprod,suquo difference, sum, product, quotient of two SU data sets via suop2suflip flip a data set in various wayssuhtmath do unary arithmetic operation on segy traces with headers valuessuinterp interpolate traces using automatic event pickingsumixgathers mix two gatherssunull create null (all zeroes) tracessuop do unary arithmetic operation on segyssuop2 do a binary operation on two data setssupermute permute or transpose a 3d datacubesuramp Linearly taper the start and/or end of traces to zerosurecip sum opposing offsets in prepared datarecip sum opposing (reciprocal) offsets in cdp sorted datasuresamp Resample in timeresamp Resample the 1st dimension of a 2-dimensional function f(x1,x2)suswapbytes Swap the bytes in SU data to convert data from big endian to little endian byte order, and vice versasutaper Taper the edge traces of a data panel to zerosutxtaper Taper in (X,T) the edges of a data panel to zerosuvcat append one data set to another, with or without an overlapping region. Data in the overlap may be determined by one of several methodssuzero zero-out data within a time windowswapbytes Swap the bytes of various data typetransp Transpose an n1 by n2 element matrix

Filtering, Transforms and Attributes

One-Dimensional Filtering

suband Trapezoid-like Sin squared tapered Bandpass filter via SUFILTERsubfilt apply Butterworth bandpass filtersuconv convolution with user-supplied filtersueipofi Eigenimage (SVD) based POlarization FIlter for three-component datasufilter applies a zero-phase, sine-squared tapered filtersufrac take general (fractional) time derivative or integral of data, plus a phase shift. Input is TIME DOMAIN datasupef Wiener predictive error filteringsupofilt POlarization FILTer for three-component datasushape Wiener shaping filtersutvband time-variant bandpass filter (sine-squared taper)suxcor correlation with user-supplied filter

Two-Dimensional filtering

sudipfilt DIP--or better--SLOPE Filter in f-k domainsufxdecon random noise attenuation by FX-DECONvolutionsuk1k2filter symmetric box-like K-domain filter defined by the cartesian product of two sin^2-tapered polygonal filters defined in k1 and k2sumedian MEDIAN filter about a user-defined polygonal curve with the distance along the curve specified by key header wordsukfilter radially symmetric K-domain, sin^2-tapered, polygonal filtersukfrac apply FRACtional powers of i|k| to data, with phase shift

Transforms and Attributes

entropy compute the ENTROPY of a signalmrafxzwt Multi-resolution analysis of a function F(X,Z) by Wavelet Transformsuamp output amp, phase, real or imag trace from domain datasuattributes trace attributes instantanteous amplitude, phase or frequencysuenv Instantaneous amplitude, frequency, and phase via: suattributessuhilb Hilbert transformsuhrot Horizontal ROTation of three-component datasufft fft real time traces to complex frequency tracessuifft fft complex frequency traces to real time tracessugabor Outputs a time-frequency representation of seismic data via the Gabor transform-like multifilter analysis techniquesuharlan signal-noise separation by the invertible linear transformation method of Harlansulog time axis log-stretch of seismic tracessuilog time axis inverse log-stretch of seismic tracessupolar POLarization analysis of three-component datasuradon compute forward or reverse Radon transform or remove multiples by using the parabolic Radon transform to estimate multiples and subtractsutaup forward and inverse T-X and F-K global slant stackssutsq time axis time-squared stretch of seismic tracessureduce convert traces to display in reduced timesuspecfk F-K Fourier SPECtrum of data setsuspecfx Fourier SPECtrum (T -> F) of tracessuspeck1k2 2D (K1,K2) Fourier SPECtrum of (x1,x2) data set

Gain, NMO, Stack and Standard Processes

Standard Processes

suagc perform agc on SU datasudipdivcor Dip-dependent Divergence (spreading) correctionsudivcor Divergence (spreading) correctionsugain apply various types of gain to display tracesgrm Generalized Reciprocal refraction analysis for a single layersumix compute weighted moving average (trace MIX) on a panel of seismic datasumute mute above (or below) a user-defined polygonal curve with the distance along the curve specified by key header wordsunmo NMO for an arbitrary velocity function of time and CDPsupgc Programmed Gain Control--apply agc like function but the same function to all traces preserving relative amplitudes spatiallysupws Phase stack or phase-weighted stack (PWS) of adjacent traces having the same key header wordsuresstat Surface consistent source and receiver statics calculationsustack stack adjacent traces having the same key header wordsustatic Elevation static corrections, apply corrections from headers or from a source and receiver statics filesustaticrrs Elevation STATIC corrections, apply corrections from headers or from a source and receiver statics file, includes application of Residual Refraction Staticsunglitch clip outliers in data

Miscellaneous

suacor Auto Correlationsuttoz Resample from time to depthsuvibro Generates a Vibroseis sweep (linear, linear-segment, dB per octave, dB per hertz, T-power)suvlength Adjust variable length traces to common length

SU community

Seismic Unix has a very large community, with lots of laboratories and researchers on the world using it. There's a listserver group where you can get help and post your questions about SU. To subscribe to it, click here.

You can also see the old posts that the users have already discussed, to do it click here

Awards

2002 - Society of Exploration Geophysicists Special Commendation

1994 - University to Industry award from the Colorado chapter of the Technology Transfer Society