Local flexures due to incomplete horizon clean-up

In the 3D structural modeling workflow, you may encounter situations in which the created horizons do not show the anticipated offset. There may be local flexures where the horizons are dragged up or downwards (see figure below). These flexures can have multiple causes, see section 'Cause' below.

Where encountered

• model > 3D Structure > Construct Surfaces
• model > 3D Structure > Fault Cutoff Line Edits

Cause

Local flexures can manifest themselves at different stages during modeling and can have multiple causes:

1. Not covered in this section:
   • Flexures of 3D grid layers around fault model inconsistencies
   • Flexures in the 3D structural model due to boundary effects
   • Pulling fault cutoff line nodes through faults
2. Covered in this section: flexures due to incomplete horizon clean-up

This section discusses local flexures as a result of incomplete horizon clean-up, where a node located on the other side of a fault leads to local pulls (up or down).

How to fix the issue

To avoid creating local flexures, you can use the Horizon Clean-up tool, or manually edit the surfaces.

The strongly recommended approach is to use the Horizon Clean-up tool and select an appropriate clean-up distance in which you ensure that nodes close to the fault surfaces (whatever side they fall on) are set to 'inactive'. Such nodes will be ignored by the gridder.

You can also use manual editing to remove the data in the close proximity of the fault. Any items sticking through the fault should be either removed or set to inactive.

Result

When you have removed data sticking though the fault or used appropriate Horizon Cleanup distances, nodes which could potentially be misinterpreted with respect to their location to the fault are likely to be excluded from the gridding operation. A successful gridder result is shown below.