Create a SEG-Y file

Create from numpy array (or binary file) and SEG-Y headers

There is often such a workflow:

  1. Display SEG-Y format data orig.segy in specialized software, such as Petrel.

  2. Use Python code to process this data and obtain new data afterprocess, which is in NumPy array format

  3. To display this processed data in specialized software, it needs to be converted back to SEG-Y format and use the headers from the original data, i.e., using the NumPy array afterprocess and the header of orig.segy to create a new SEG-Y file out.segy.

You can use cigsegy.create_by_sharing_header to create a new SEG-Y file out.segy whose headers are same as orig.segy.

# read orig.segy to numpy array
>>> orig = cigsegy.fromfile('orig.segy', 9, 21)
>>> orig.shape
# (589, 762, 1001)

# do some prosess
>>> afterprocess = do_some_process(orig)
>>> afterprocess.shape
# (589, 762, 1001)

# assume the iline/xline/istep/xstep of **orig.segy** are 9/21/1/1
>>> cigsegy.create_by_sharing_header('out.segy', 'orig.segy', afterprocess, \
    keylocs=[9, 21, 1, 1])

# using binary file instead of numpy array
# assume shape = (589, 762, 1001) = (n-inline, n-crossline, n-time)
>>> cigsegy.create_by_sharing_header('out.segy', 'orig.segy', 'afterprocess.dat', \
    (589, 762, 1001), keylocs=[9, 21, 1, 1])

If afterprocess is a sub-volume, i.e., only process a part of orig.segy, you can set start=(iline_start, xline_start, time_start) to create a new SEG-Y file.

For example:

# read orig.segy to numpy array
>>> orig = cigsegy.fromfile('orig.segy', 9, 21)
>>> orig.shape
# (589, 762, 1001)

# cut orig, only process a part of orig array
# offset is (100, 400, 300)
>>> toprocess = orig[100:520, 400:700, 300:900]
>>> afterprocess = do_some_process(toprocess)
>>> afterprocess.shape
# (420, 300, 600)

# create 'out.segy' using afterprocess (data) and a part
# of header in 'orig.segy'
>>> cigsegy.create_by_sharing_header('out.segy', 'orig.segy', afterprocess, \
    keylocs=[9, 21, 1, 1], start=(100, 400, 300))

Note

For all create-like functions, you can speacify the textual to custom textual header, e.g.,

# you can special the first 12 lines of textual header
>>> textual12 = "xxxxx"
>>> cigsegy.create_by_sharing_header('out.segy', 'orig.segy', afterprocess, \
    keylocs=[9, 21, 1, 1], start=(100, 400, 300), textual=my_info)
>>> cigsegy.textual_header('out.segy')
# xxx

Create from numpy array and some parameters

# d is a numpy array, d.shape == (n-inlines, n-crosslines, n-time)
>>> cigsegy.create('out.segy', d, format=5, start_time=0, iline_interval=15, ...)