DUG Insight User ManualDUG Insight LearningFrequently Asked QuestionsHorizonsHow to mark a pinchout/intersection of two surfaces using a polygon?

# How to mark a pinchout/intersection of two surfaces using a polygon?

Investigating stratigraphic traps or a stratigraphic surface which has been interrupted by a fault?  How do we map the resultant pinchout/intersection between these two horizons using DUG-Insight?  The workflow below discusses how to create a detailed polygon outlining the pinchout/intersection.

## Workflow

1. Pick the top (h1) and base (h2) horizons of your pinchout structure
2. Create a pinchout horizon using Horizon maths
• Inputs: h1 = top horizon, h2 = base horizon
• Formula: if (h1<h2, h1, nan)
• (If top horizon is greater than base horizon use top horizon.  If not use nan as value.)
1. Create a constant horizon using the Constant horizon
• Value: 0 ms
• Vertical: TWT
• Output grid: polygon which covers entire horizon area
• Spacing: 100
• Survey: Same 3D survey as original horizons
1. Merge the pinchout horizon created in step 2 and constant horizon created in step 3 using Horizon Maths
• Inputs: h1 = pinchout horizon, h2 = constant horizon
• Formula: merge (h1, h2)
• (Merge pinchout horizon and constant horizon, give priority to pinchout horizon)
1. Display in Map View.

We now have the intersection represented clearly on the merged horizon.  Create a polygon along this boundary using create polygon from contours tool.

1. Open Display tab and select contours
2. Display 0 contour in Map View
1. Create polygon from contour 0 using Create contour Polygons
1. Final polygon showing pinchout intersection.