Reading and Writing SEGY Seismic Data Files

The SEGY format is a standard data storage format commonly used in seismic exploration, storing seismic trace data, sampling information, and related metadata in binary form. In MATLAB, reading and writing SEGY files can be achieved using built-in functions or third-party toolkits, with relatively simple and efficient operations.

For reading SEGY files, MATLAB provides basic binary file operation functions. Users can follow the SEGY format specifications by first reading file header information—including key parameters such as sample interval and trace count—using functions like fread with appropriate byte ordering. Subsequently, seismic data can be read trace by trace, where each trace typically consists of a trace header followed by amplitude samples. For large SEGY files, a chunk-based reading strategy is recommended to prevent memory issues, implemented through loop structures with offset calculations.

When writing SEGY files, correct configuration of binary headers and data formats is crucial. MATLAB's fwrite function is well-suited for this task. The process involves first writing a compliant binary file header with proper parameter settings (e.g., sample rate, data format code), followed by sequentially writing each trace’s header and data. Special attention must be paid to byte order (endianness), ensuring consistency with standard SEGY specifications using fopen options like 'ieee-be' for big-endian format.

To simplify operations, specialized geophysical toolkits such as MATLAB’s SEGY Toolkit or open-source libraries (e.g., SegyMAT) can be employed. These tools typically offer high-level interfaces that automatically handle format details—including header parsing, data scaling, and geometry mapping—allowing users to focus on data analysis through functions like segyread for direct struct-based data import.