Stratal Slicing using 3D Model-driven Chronostratigraphy G. de Bruin

Introduction Horizon based attribute analysis can reveal sedimentary and structural features Since horizon-tracking is time-consuming, only the key horizons are typically tracked. Therefore, only a small part of the available data is usually analyzed

Introduction To analyze more data, horizons are often shifted, which is in most cases only valid in the vicinity of the original horizon Proportional slicing or stratal slicing enables a more accurate analysis Decrease of horizon quality Geological situation Shifting lower horizon Shifting upper horizon Stratal-slicing

Introduction Stratal slicing or proportional slicing is possible in OpendTect, through the use of the linear interpolation option of the SSIS plugin Stratal slicing is performed in the chronostratigraphic or Wheeler domain

Seismic: Wheeler transformation Seismic Domain Wheeler Domain Geo-time ms A horizon in the seismic domain is represented by a time-slice in the wheeler domain Therefore: time-slicing in the Wheeler domain is horizon / stratal slicing in the seismic domain We analyze the data on time-slices in the Wheeler-domain, simply because it is much easier to display a time-slice than a horizon. Horizons have a geometry, time-slices don’t. Thus more data can be displayed and this is done faster.

Workflow Track or import 2 horizons Calculate chronostratigraphy Create Wheeler volume Load Volume in Wheeler scene Required Software: OpendTect Base SSIS plugin

Track 2 horizons Track 2 horizons* Make sure to fill all holes Check for crossing horizons * Consult OpendTect user-documentation http://www2.opendtect.org/rel/html/index.html

Calculate Chronostratigraphy SSIS > Chronostratigraphy > new Read the 2 horizons Set both to isochronous Set spacing Give a name

Create Wheeler Cube SSIS > Chronostratigraphy > Select SSIS > Create Wheeler Cube Select a seismic volume Give a name

Load Volume in Wheeler SSIS > Add Wheeler Scene Add Volume in Wheeler Scene

Time-slice through volume Drag the time-slice for stratal slicing