SEG-Y

SEG-Y
Name	SEG-Y
Type	Data format
Introduced	1975
Developer	Society of Exploration Geophysicists
Extension	.sgy, .segy
Latest release	Revision 2.0 (2017)
Genre	Seismic data interchange

SEG-Y SEG-Y is a binary interchange format for storing reflection seismic data, created to facilitate exchange among geophysicists, survey contractors, oil companies, service companies, and software vendors. Originally developed by the Society of Exploration Geophysicists, SEG-Y became a de facto standard for seismic processing, interpretation, and archival workflows used by organizations such as ExxonMobil, Schlumberger, BP, Shell, and Chevron. The format's longevity is tied to broad adoption across institutions like the United States Geological Survey, British Geological Survey, Norwegian Petroleum Directorate, and academic centers including Massachusetts Institute of Technology, Stanford University, Imperial College London, and University of Texas at Austin.

Overview

SEG-Y was introduced to address interoperability among producers and consumers of seismic reflection data; it complements earlier formats such as SEG-D and later standards like SEG-2. The design emphasizes a fixed textual header and binary headers enabling compatibility with mainframe systems at institutions like IBM, Hewlett-Packard, and Sun Microsystems while supporting modern platforms from Microsoft, Apple, Red Hat, and Canonical. Prominent exploration companies including Anadarko Petroleum, TotalEnergies, Repsol, Petrobras, Equinor, and ConocoPhillips long relied on SEG-Y archives alongside national datasets from Norway, United Kingdom, United States, Canada, Australia, and Brazil. Academic research at Columbia University, Oxford University, ETH Zurich, and Caltech often uses SEG-Y for teaching seismic processing and migration methods associated with names like Walter M. Smith, Enders A. Robinson, and Jon Claerbout.

File Format and Structure

A SEG-Y file consists of a 3200-byte textual header and a 400-byte binary header followed by a sequence of trace headers and trace data samples. Vendors such as Halliburton, Baker Hughes, WesternGeco, and CGG provide acquisition systems that output traces in this layout, while software suites from Landmark, Paradigm, Petrel, OpendTect, and Madagascar implement readers and writers. The textual header historically used EBCDIC encoding for compatibility with IBM mainframes but later allowed ASCII to accommodate systems from Microsoft and Apple; this choice affects interoperability across platforms used by NOAA, NASA, and ESA. The binary header encodes sample interval, sample format code, number of samples, and other metadata used by processors at Schlumberger Research, Chevron Energy Technology Company, and academic groups at University of Houston and University of Calgary.

Headers and Trace Data

Trace headers provide per-trace metadata such as trace sequence number, source and receiver coordinates, elevation, depth, and sample count; these fields are critical to processing steps like stacking, filtering, and migration performed using algorithms developed by researchers at Stanford, MIT, and Delft University of Technology. Vendors and service companies—WesternGeco, PGS, TGS, Shearwater, Spectrum—map acquisition parameters into trace header offsets standardized by the Society of Exploration Geophysicists committee work including contributors from Petrobras, Saudi Aramco, and National Oilwell Varco. Sample formats supported include IBM floating point, IEEE 32-bit float, 16-bit integer, and 32-bit integer, affecting data handling in libraries such as Seismic Unix, ObsPy, GDAL, and HDF5-based tools used by CERN, NOAA, and AWI.

Variants and Revisions

SEG-Y has undergone revisions to address changing needs: the original 1975 edition, an informal wide adoption era, and the formal Revision 1.0 and Revision 2.0 updates led by SEG committees with input from companies like BP, Shell, and academic bodies including University of Leeds and Curtin University. Revisions introduce optional extended textual headers, support for 64-bit offsets, and standardized vendor-specific trace header extensions adopted by commercial products from IHS Markit, OpenWorks, and Kingdom Suite. Regional initiatives—Norwegian Petroleum Directorate, BGS, Geoscience Australia—drive profile specifications that coexist with vendor extensions used by Petrobras and Pemex.

Usage and Applications

SEG-Y is ubiquitous in exploration and production activities: seismic interpretation, velocity model building, depth conversion, time migration, and reservoir characterization workflows used by geoscientists at ExxonMobil, Chevron, TotalEnergies, and Equinor. Academic studies in seismic tomography, full-waveform inversion, and passive seismic analysis at institutions such as MIT, Princeton, University of Cambridge, and University of Tokyo also use SEG-Y for data exchange. Public repositories and consortia—the USGS, IRIS, OpenTopography, and the UK National Geoscience Data Centre—distribute datasets in SEG-Y for research into earthquakes, basin analysis, and CO2 sequestration projects spearheaded by research networks including the European Research Council and National Science Foundation.

Tools and Implementation

Open-source tools and libraries provide reading, writing, and visualization capabilities: Seismic Unix, OpendTect, Madagascar, ObsPy, and Segyio are widely used alongside commercial packages from Paradigm, Landmark, and Schlumberger. Developers integrate SEG-Y support in languages and environments including Python, C/C++, Fortran, Java, Julia, and MATLAB, leveraging frameworks like NumPy, SciPy, pandas, and TensorFlow for machine learning research at Google DeepMind, IBM Research, and Microsoft Research. Cloud platforms—Amazon Web Services, Google Cloud Platform, Microsoft Azure—host SEG-Y archives for large-scale processing using HPC centers such as NERSC, PRACE, and national laboratories like Lawrence Berkeley, Sandia, and Los Alamos.

Standards and Governance

Governance of the format is overseen by the Society of Exploration Geophysicists through standards committees and working groups that include participants from Schlumberger, Halliburton, CGG, PGS, and national geological surveys. Standards development intersects with organizations and events such as SEG Annual Meeting, EAGE, AGU Fall Meeting, and SPE conferences where experts from Imperial College London, University of Alberta, and King Abdullah University of Science and Technology discuss best practices. Adoption and conformance testing involve service companies, software vendors, and academic labs contributing to interoperability efforts supported by industry consortia and government agencies including DOE and CSIRO.

Category:Seismic data formats