Seismic horizon correlation is aimed at mapping continuous reflectors that represent geological horizons across a seismic dataset. The process relies on several core principles:

Waveform Continuity, Stratigraphic Context, Well Data Integration, Spatial Consistency.

These principles underpin the practical steps for seismic horizon correlation in g-Space, which includes Well tie, Horizon picking, and Mapping.

Notes

Methodological Approaches

1. Phase correlation focuses on tracing reflectors by maintaining the continuity of specific phases (peaks, troughs, or zero crossings).

This method is effective in areas with clear, consistent reflectors. It involves:

• Picking a phase (e.g., peak or trough) and tracing it across the dataset.
• Ensuring that the selected phase remains consistent across traces, using g-Space tools to automatically track reflectors where possible.

2. Seismostratigraphy is the process of identifying depositional sequences and stratigraphic surfaces from seismic reflection patterns. This method is often used to:

• Identify key stratigraphic boundaries (e.g., unconformities or maximum flooding surfaces).
• Correlate horizons based on depositional features such as onlaps, downlaps, or erosional surfaces.

Begin picking horizons at well locations where the reflectors have been tied to known formations using the Well tie functionaity.

To create a new horizon go to Data manager and press Right Click Mouse on the Horizon icon. Choose Add new horizon

or on Seismic view in tool bar press Horizon picks button and press Alt + Right Click Mouse button on seismic view and choose Create new horizon

Let’s set up a workspace for horizon picking. In this example, a map is displayed showing a seismic volume, inline and crossline sections, wells, as well as inline and crossline views with linked wells, synthetic traces, and markers. The Interpretation bar provides the picking settings used in this workflow.

Subscribe to our channel and watch the video on how to pick horizons in g-Space on YouTube

Click on Horizon Pick (highlighted in red) in the top panel of the view to begin picking horizons.

The same Horizon picks tool is available outside a time section: on depth Inline, Crossline and Arbitrary line sections (see Seismic view for opening a view in the depth domain) and in the 3D Time and 3D Depth views. All of them also carry the Unlocked horizon picks and Tracking horizon picks items, so manual and tracking picks stay visible while you work. In a 3D view you pick by clicking a section shown in the scene - a 2D line, an arbitrary line, an inline or crossline section, or an inline or crossline face of a seismic volume - and the picks go to the current horizon.

Only your own horizons can be edited. When the horizon and the view are in different domains - a time horizon picked on a depth view, or a depth horizon picked on a time view - g-Space converts the pick through the current velocity model, so select one first; without it the pick is not added.

Set the picking behavior in the Picking group on the Interpretation bar. Pick mode is set to Autopicking by default, so change it there first if you want to pick manually. The mode-specific workflows are described below.

Autopicking can also be restricted to one area of the survey. Open the Module Properties panel and expand the Picking parameters group. While Pick mode is Autopicking, this group also offers the Limit auto picking to polygon checkbox (cleared by default) and the Auto picking polygon drop-down (empty by default). These two settings stay in Module Properties and are not part of the Picking group on the bar.

The drop-down lists every polygon of the project as <polygon name>-<user>, and its empty first entry means no restriction. The list is filled when a project is opened and refreshes automatically when polygons are added, renamed, deleted or imported, so a polygon stored with the project can be selected straight away.

Select the checkbox and choose a polygon to autopick only the bins inside it: the spread stops at the polygon boundary, and bins outside it are neither picked nor overwritten. The polygon limit works together with Auto picking radius limitation, so when both are set a bin has to satisfy both. Clear the checkbox or leave the polygon empty to remove the restriction. The limit applies to Autopicking only: in Tracking, Interpolation, Continuous and Autopicking -- Multi-Horizon mode the two settings are hidden and have no effect.

The Pick mode list offers Tracking, Interpolation, Continuous, Autopicking and Autopicking -- Multi-Horizon, the last of which autopicks several horizons in one pass. The Tracking, Interpolation and Continuous workflows are described below:

1. Tracking: Automatically follows seismic events across the section based on the selected pick phase. Click the left mouse button, in the example the click points are highlighted with black circles, to finish, click the left mouse button twice

Notes

In tracking mode, the software automatically follows a seismic event based on amplitude and phase consistency. This is ideal when horizons are well-defined and exhibit minimal interruptions or distortions, such as in clear stratigraphic layers. It reduces the amount of manual picking and ensures consistent interpretation over large sections.

To delete a segment of interpretation, press and hold the right mouse button and select the area to delete. You can also immediately proceed to editing and put new points on these segments.

In Tracking mode, when moving to another section, right-click the seismic view and choose Track horizon. g-Space automatically correlates the horizon on the newly opened section.

1. Interpolation: Picks points at intervals and interpolates between them to define the horizon.

Notes

Interpolation mode is useful when seismic horizons are partially obscured, interrupted by faults, or have variable continuity. The user selects key points along the horizon, and the software interpolates between these points to create a complete pick. This approach balances manual input with automatic interpretation, allowing for more flexibility in challenging areas with less-defined reflectors.

1. Continuous: Enables continuous manual picking across the section, allowing the user to define the horizon in real-time. The process looks like drawing on a seismic image.

Notes

Continuous mode is fully manual and allows the interpreter to continuously pick the horizon across the section. This mode is helpful when there are significant geological complexities, such as in areas with faulting, folding, or high noise levels, where automated tracking or interpolation might not perform accurately. The interpreter retains full control over the horizon pick, ensuring precision in difficult regions.

Hot keys for seismic section views:

Up and Down move the active section up and down in the set scale

Ctrl+Left and Ctrl+Right move crosslines with a set step

Ctrl+Up and Ctrl+Down move inlines with a set step

Or Page Up and Page Down buttons move both inlines and crosslines in the active view

During the horizon picking process, the horizon surface is updated in real-time within the map view.

When interpreting seismic volume areas remote from wells, across fault blocks, or around geological features that disrupt reflecting horizons, the ghosted view tool in g-Space is particularly useful. This tool allows the user to take a screenshot of a specific interpretation, drag it to a new location, and overlay it on the current view, simplifying the horizon picking process.

Additionally, the tool enables rotation of the screenshot, making it adaptable to various structural alignments. This method is particularly effective in complex tectonic settings, ensuring more accurate seismic horizon correlation.

Open drop-down menu in Tools in Main bar and choose Show capture view or use hot keys Ctrl + Alt + P

The Flatten Horizon tool can be very useful to effectively remove structural complexities and focus on stratigraphy.  

To flatten a seismic section to a specific horizon, right-click on the horizon name and select Set as flatten from the drop-down menu. The seismic section will then be flattened to the selected horizon. To return to the normal view, repeat the steps and choose Unset as flatten.

When a section is flattened to a horizon, Autopicking and Autopicking -- Multi-Horizon work on the flattened seismic you see instead of the originally loaded section, so an event that is easier to follow after flattening can be autopicked there. The picks are saved with their original time or depth values, so they stay in the correct position when you choose Unset as flatten.

The outcome of the interpretation consists of points, each associated with a specific set of attributes, Time in our case.

There is a drop down menu in Data manager for Horizons where user can create maps, flatten horizons, set colors, etc.  At any point user can rebuild the map of the selected horizon.

For 3D visualization, g-Space offers a feature that allows time-domain data to be displayed within the 3D depth view using the current velocity model.

This is especially useful during interpretation, as it enables reviewing results in time without requiring full data conversion to the depth domain