SEG-Y Import

SEG-Y Import

The prestack data must be sorted in either shot or station plane. Phoenix will scan all files to determine the order.

Following the SEG/SPS standard, shots and stations are identified by three numbers: LineNumber, PointNumber, and PointIndex. Of the three only PointNumber is required to be defined in the header map file.

Open the SEGY import wizard

Open the Phoenix application window and select “Project creation” ==> “SEGY data”. Note that the required and suggested headers are described on the right.

Define the header map

Click on “Open SEGY dictionary editor”. The dialog that opens is fairly self-explanatory and should be easy for experienced Flatirons users.

Click “Select SEGY file” to open one of the files to be imported, then click the “New” icon (the blank page icon halfway down on the left) to create a new header map file.

The newly created map has some default values filled in. The coordinate and elevation entries will probably be correct. However, it’s very likely that the LineNumber and PointNumber fields will be incorrect and will need to be updated.

As you edit the map keep an eye on the imported values displayed under “Trace header #1” in the lower-right. They show the results of the import operations.

It often happens that it’s unknown where values are stored in the headers. The “Scan header ranges” tab can help find them:

After the map has been defined it’s usually a good idea to view the data in the “Trace viewer” tab. Be sure to check the header values in the header plot displays – just click on the plot header to select a new value.

Select the map file and SEGY files

Close the dictionary editor and in the SEGY import dialog select the new header map.

Select one or more SEGY files. Note that the same header map is used for all of the files. The current survey consists of four small synthetic files:

Define the new project name / location

Click “Next” to go to the next page in the wizard:

There are two important options on this page – give the new project a name and select in which PhoenixData directory to store the imported data.

Most of the remaining options are easily understood. When importing really huge surveys it may make sense to both limit the maximum offset and decimate the imported traces.

Click “Next” to go to the final page.

Dataset and Merge creation

The following is confusing for new users. You can safely accept the defaults on this page and learn about “project logic” later.

The “project logic” in Phoenix is key to handling very large surveys. It divides data into two distinct layers. The “Dataset” layer contains the seismic data, the shot and receiver tables, and the trace table which holds pick information. Users don’t directly interact with dataset objects. Users interact with “Merge” objects, which use references to one or more dataset objects. The merges contain delay time models, tomography models, etc.

The current version of Phoenix allows three methods of storing Dataset information. The PostgreSQL method is the slowest but also the most robust. Future versions of Phoenix will use a variety of “Big Data” storage solutions.

The “Dataset/Merge creation options” is very important for program performance. Just leave the second option selected (assuming you’re importing more than one file) unless you have a good reason.

Click “Finish”. The import will run as a batch job, so you may continue working with Phoenix on other projects.