Stratal Slicingusing 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

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

Introduction

Geological situation Shifting lower horizonShifting upper horizon

Stratal-slicing

Decrease of horizon quality

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 Domainm s

Geo-

tim

e

A horizon in the seismic domain is represented by a time-slice in the wheeler domainTherefore: 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

http://www2.opendtect.org/rel/html/index.html

1. Track 2 horizons*

2. Make sure to fill all holes

3. Check for crossing horizons

* Consult OpendTect user-documentation

Calculate Chronostratigraphy

1. Read the 2 horizons

2. Set both to isochronous

3. Set spacing

4. Give a name

SSIS > Chronostratigraphy > new

Create Wheeler Cube

SSIS > Chronostratigraphy > Select

SSIS > Create Wheeler Cube

1. Select a seismic volume

2. 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