Theory

A CDP (Common Depth Point) — also called CMP (Common Midpoint) — is a unique identifier assigned to a reflection point on the surface halfway between a seismic source and receiver.

The CDP number (or bin number) represents which midpoint bin that trace belongs to — grouping all traces that reflect from roughly the same subsurface point.

Why CDP Numbers Are Important?

• They define the geometry of stacking and velocity analysis.
• Processing steps such as velocity picking, NMO, and stacking are done on CDP gathers, not random traces.
• CDP numbers link traces that share the same subsurface reflection point.

Without correct CDP numbering, stacking and imaging would combine traces from different physical locations, creating severe artifacts.

Why Do We Need to Recreate CDP Numbers?

We recreate (or regenerate) CDP numbers when the existing numbers:

• Are missing (e.g., in raw field data).
• Are wrong due to incorrect geometry assignment.
• Don’t match the updated bin grid (after coordinate reprojection, merging, or resampling).
• Need to be recomputed after any geometry change (e.g., line shift, regridding, or merge of two surveys).

When Do We Recreate CDP Numbers?

We’ll recreate CDP numbers:

• During geometry definition or rebuild (after loading SPS or P190 navigation files).
• After editing coordinates (correcting shifts, mismatches, projection changes).
• Before velocity analysis or stacking, if QC shows inconsistent CDP grouping.
• When integrating data from different acquisition phases into one project.
• Before 3D binning, when defining the inline/xline structure.

Input data

SEG-Y data handle

connect/reference to Output SEG-Y data handle.

Original trace headers

connect/reference to the input trace headers. These trace headers are going to be updated with new CDP numbers after assigning the trace headers stack geometry.

Trace headers Stack Geometry

this information uses to create new CDP numbers by using the stack geometry trace headers information.

Output file name

specify the output gather name after recreating the CDP numbers.

Parameters

Use bins for compare

this parameter allows the user to compare the previous and updated bins information.

Settings

Number of threads

One less than total no of nodes/threads to execute a job in multi-thread mode. Limit number of threads on main machine.

Skip

By default, FALSE(Unchecked). This option helps to bypass the module from the workflow.

Output data

There are no output vista items for this module. There will be a output gather which needs to be defined in the Input data tab.

Information

There is no information available for this module so the user can ignore this.

Examples

Actions

There are no action items available for this module.

Video lesson

YouTube video lesson, click here to open [VIDEO IN PROCESS...]

Related articles

Yilmaz. O., 1987, Seismic data processing: Society of Exploration Geophysicist

* * *   If you have any questions, please send an e-mail to: support@geomage.com  * * *