SEGY Swiss Army Knife for Seismic Data
SEGY-SAK is a took for manipulating SEGY format seismic data. It builds upon the work of segyio to provide a more
user friendly interface for manipulating and accessing information within SEG-Y data.
SEGY-SAK can be used as either a functional library within your own project to more easily access SEG-Y data or alternatively, a command line interface (CLI) is offered that allows you to examine, manipulate and convert SEG-Y data without writing Python scripts.
SEGY-SAK also offers a to-from converter for xarray and Python friendly formats such as NetCDF4 and Zarr*. These are
highly performant file formats designed for buffered and distributed processing, a necessity when it comes to large
seismic data volumes.
- Convert 3D SEGY to NETCDF4 and back.
- Extract sub-volumes via cropping.
SEGY-SAK can be installed by using python setuptools.
Clone the SEGY-SAK Github repository and in the top level directory
python setup.py install
The command line interface (CLI) provides an easy tool to convert or manipulate SEG-Y data. In your Python command-line
environment it can be accessed by calling segysak.
See segysak --help for options.
SEG-Y files converted using segysak -nc -F test.segy for example can be loaded into Python using xarray.
test = xarray.open_dataset('test.SEISNC')
The xarray seismic specification used by segysak to output NETCDF4 files is more performant for Python operations than
standard SEG-Y. Unlike SEG-Y, xarray compatable files fit neatly into the Python scientific stack providing operations
like lazy loading, easy slicing, compatability with multi-core and multi-node operations using dask as well as
important features such as labelled axes and coordinates.
This specification is not meant to be prescriptive but outlines some basic requirements for SEGYSAK to work.
SEGYSAK uses the convention .SEISNC for the suffix on NETCDF4 files it creates. These files are datasets with many 1D
and 2D variables and a single 3D variable called data. The data variable contains the seismic cube volume and other
variables are used to describe the coordinate space. Attributes can be used to provide further metadata about the cube.
The basic dimensions are i, j and k. These are simply sequential indicies in the inline, crossline and vertical
directions. The iline, xline and vert variables contain the associated coordinates. These 6 variables are mandatory.
Non-mandatory variables are CDP_X, CDP_Y and CDP_TRACE which can contain additional coordinate data.
Any number of attributes can be added to a SEISNC file. Currently the following attributes are extracted.
nsNumber of samples per trace.dsSample intervaltextThe ebcidc header