SEG-Y via Xarray

Opening SEG-Y Data

SEGY Backend for reading Seismic SEGY files.

`SgyBackendEntrypoint`

Bases: BackendEntrypoint

`open_dataset(filename_or_obj, dim_byte_fields, drop_variables=None, head_df=None, extra_byte_fields=None, segyio_kwargs=None)`

Open a SEGY file with a native Xarray front end.

Parameters:

Name	Type	Description	Default
`filename_or_obj`	`Union[str, PathLike]`	The SEG-Y file/path.	required
`dim_byte_fields`	`Dict[str, int]`	Dimension names and byte location pairs. This should at a minimum have the keys `cdp` or `iline` and `xline`.	required
`drop_variables`	`Union[tuple[str], None]`	Ignored	`None`
`head_df`	`Union[DataFrame, None]`	The DataFrame output from `segy_header_scrape`. This DataFrame can be filtered by the user to load select trace sets. Trace loading is based upon the DataFrame index.	`None`
`extra_byte_fields`	`dict`	Additional header information to load into the Dataset. Defaults to None.	`None`
`segyio_kwargs`	`Union[dict, None]`	Extra keyword arguments for segyio.open	`None`

Returns:

Type	Description
`Dataset`	Lazy segy file Dataset

Example

This backend is registered within Xarray and is accessed automatically when using the xr.open_dataset method for files with extensions of .segy and .sgy.

Ensure the byte locations are correct for your data.

Python

# 3D data
ds3d = xr.open_dataset(
    segyfile_path,
    dim_byte_fields={'iline':189, 'xline':193},
    extra_byte_fields={'cdp_x':181, 'cdp_y':185},
)

# 2D data
ds2d = xr.open_dataset(
    segyfile_path,
    dim_byte_fields={'cdp':22},
    extra_byte_fields={'cdp_x':181, 'cdp_y':185},
)

Saving SEG-Y Data

`SegyWriter`

Handles the writing of SEG-Y files from compatible Datasets. Usually this class would not be used and SEGY-SAK users can write SEG-Y file via the seisio accessor.

Example

Writing data with the seisio accessor.

Python

ds.seisio.to_segy()

`to_segy(ds, data_var='data', vert_dimension='samples', dead_trace_var=None, trace_header_map=None, **dim_kwargs)`

Output xarray dataset to SEG-Y format.

Parameters:

Name	Type	Description	Default
`ds`	`Dataset`	The input dataset	required
`data_var`	`str`	The Dataset variable name for the output volume.	`'data'`
`vert_dimension`	`str`	Data dimension to output as vertical trace, defaults to 'samples'.	`'samples'`
`dead_trace_var`	`Union[str, None]`	A variable in the Dataset which signifies dead traces.	`None`
`trace_header_map`	`Dict[str, int]`	Defaults to None. A dictionary of Dataset variables and byte locations. The variable will be written to the trace headers in the assigned byte location. By default CMP=23, cdp_x=181, cdp_y=185, iline=189, xline=193.	`None`
`dim_kwargs`		The dimension/byte location pairs to output dimensions to. The number of dim_kwargs should be equal to the number of dimensions on the output data_array. The sort order will be as per the order passed to the function.	`{}`

`write_text_header(text, line_numbers=True)`

Write the text header for the file. The line length limit is 80 characters.

Parameters:

Name	Type	Description	Default
`text`	`str`	The text to write, new lines have newline character `\n`. Long lines will be truncated.	required
`line_numbers`	`bool`	Add line numbers to the output text header.	`True`