DUG Insight User ManualFrequently Asked QuestionsFrequently Asked Questions WorkflowsGenerating synthetic stacks from Intercept and Gradient volumes

Generating synthetic stacks from Intercept and Gradient volumes

An overview of the workflow:

  1. Calculate reference angle stacks from the gathers (see Angle Stacks).
  2. Calculate intercept and gradient from the gathers (see Intercept/Gradient).
  3. Use Shuey's approximation to calculate the synthetic volume (see Volume Maths).
  4. (optional) Band-limit the synthetic to match the reference stack (see Band-pass Filter).
  5. Calculate the residual using Volume Maths.

Setup

In this example, we prepared the following data:

For Angle Stacks

  • Load gathers
  • Load velocity model

For Spectral Analysis

For I/G calculation (from gathers)

Use this workflow. Repeat steps 3, 4 and 5 for additional angles.

The spectral analysis window is included as a reference.

  • Yellow = Stack
  • Orange = Synthetic
  • Red = Filtered Synthetic
  • Black = Residual

Workflow

  1. Create angle stacks from the gathers. We will be using the average of the min and max stacking angle for Shuey's equation.
  1. Calculate Intercept and Gradient from the gathers. Use angle mutes to avoid including near-offset noise and NMO stretch.
  1. Use Volume Maths and Shuey's equation to calculate the amplitude using the Intercept and Gradient results for a specific angle. Note that the trigonometric functions expect radians as input (e.g. for 30 degrees).
    • Formula: I + G * (sin(30*pi/180)^2)
  1. Depending on your data, the synthetic result may contain more high-frequencies than your angle stack, increasing the energy in the residual. By applying a bandpass filter, we can match the synthetic spectrum to the stack spectrum.
  1. Finally, calculate the residual between the stack and the synthetic using volume maths.