Friday, 3 June 2016

Angle Stacks and CMY Blending

CMY Blending is a very powerful Cognitive Interpretation technique in GeoTeric that can be used to reveal faults and stratigraphic or carbonate features. In this example we will look at using Structurally Oriented Semblance on angle stack data from the Taranaki Basin, New Zealand. After conditioning the data (noise attenuation and spectral balancing) for all three angle stacks, we can create SO Semblance attributes. This can be done in the Fault Expression tool or also in the Batch Processor: Processes>Attributes>Edge Attributes>SO Semblance. For more information on edge attributes click here: http://blog.geoteric.com/2013/05/edge-attributes-which-one-should-i-be.html

Quite often, geological features can be masked by a full stack volume. Therefore looking at three angle stacks in single blend can help the interpreter reveal geological features more clearly.


To create a CMY blend using the angle stack SO Semblance volumes, click on Tools>New Colour Blend. The Near, Mid and Far SO Semblance volumes can be put in the respective inputs. After clicking on “set blend”, the result can be previewed on any slice or a horizon. The most crucial step is to select “Uniform Stretch” to make sure the scaling parameters are equal between the volumes blended. The default RGB scheme can then be switched to CMY. This unique ability to preview the colour blend on any slice or horizon prior to actual generation allows the interpreter to save a considerable amount of time and work more efficiently.


In the image below for example, we have the full stack SO Semblance, where the channel edges are not continuous everywhere and some channel features are quite subtle.


While in the CMY blend below, the parts of the channels where the edges appear washed out are more clearly delineated. It also effectively shows where in the blend each angle stack’s contribution is. In the red circle for example the far stack response shows a clearer edge which has been potentially masked by the full stack. 


The unique, quantitative nature of GeoTeric’s colour blends also means that they can be interpreted on directly in GeoTeric without any compromise on resolution, however the user is also free to export them using the various links such as the Link to Petrel or DecisionSpace. The colour blends transferred using the links will retain more of the resolution compared to those that are exported as SEGYs. 






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