DUG Insight User ManualDUG Insight LearningFrequently Asked QuestionsHorizonsHow do I extract the number of events between 2 time horizons?

# How do I extract the number of events between 2 time horizons?

Use this workflow to calculate a rough estimate for event counts, based on average frequency and time thickness of the target zone. This example calculates the seismic event counts from TopRes to BaseRes horizons for a 3D seismic volume in time.

Step1: Create an  instantaneous frequency for stack:

1. Go to Control panel > Process and add an Instantaneous Attributes process
2. Select the volume.
3. Select the Frequency checkbox.

Step 2: Calculate average of instantaneous frequency (Ave_IF) from the top to bottom horizon:

1. Go to Control panel > Map view.
2. Click the Operations tab and select Amplitude Extraction from the Operation dropdown menu.
3. Under Horizons, use this configuration:
• Top: pick Horizon from the dropdown and select the top horizon e.g. TopRes.
• Bottom: pick Horizon from the dropdown and select the bottom horizon e.g. BaseRes.
4. Use the created volume from the Instantaneous Attributes process e.g. instantaneous attributes: frequency.
5. Use Simple Average as the property.
6. Click Run.

Step 3: Calculate time thickness from the top to bottom horizon:

1. Calculate time thickness from the top to bottom horizon:
2. Go to Control panel > Map view.
3. Click the Operations tab and select Horizon Maths from the Operation dropdown menu.
4. Add 2 symbols by clicking the blue "+" button and set:
• h1: top horizon e.g. TopRes
• h2: bottom horizon e.g. Base Res
5. Use formula: h2 - h1.
6. Click Run.

Step 4: Calculate Number of events from top to bottom horizon:

1. Go to Control panel > Map view.
2. Click the Operations tab and select Horizon Maths from the Operation dropdown menu.
3. Add 2 symbols by clicking the blue "+" button and set:
• h1: the calculated average of instantaneous e.g. Ave_IF
• h2: the calculated time thickness e.g. Thickness_time
4. Use formula: Ave_IF x (Thickness_time / 2000) or h1 * (h2 / 2000).
5. Click Run.

The results can be QC with the Event counts graphed on top of the seismic section by writing the results from step 4 to one of the unused header in the seismic:

1. Go to Control panel > Process.
2. Click the blue "+" button and add a Header Maths process.
3. Select the seismic in the Volume search box.
4. Add a new symbol by clicking the blue "+" button.
• Select the "Event counts" horizon as h1.
5. Add a new header formulae by clicking the blue "+" button:
• Select header: 105 laga: SEG-D Skew.
• Use formula: if (isnan(h1), nan, h1).

Note: To QC this event, use the IL/CL view and enable header graphs.