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== What does curvature reveal about the subsurface? ==
 
== What does curvature reveal about the subsurface? ==
 
Curvature is an extremely useful seismic attribute, as it can help us image the shape of features in the subsurface.  For instance, anticlinal features would have a positive curvature, while synclinal features would have a negative curvature.  Flat features, or those with a constant dipping place would exhibit a curvature close to zero.
 
Curvature is an extremely useful seismic attribute, as it can help us image the shape of features in the subsurface.  For instance, anticlinal features would have a positive curvature, while synclinal features would have a negative curvature.  Flat features, or those with a constant dipping place would exhibit a curvature close to zero.
[[File:Curvature_2.jpg|thumb| Three-dimensional quadratic shapes expressed as a function of positive (kpos) and negative (kneg) curvature. <ref name=marfurt>[http://library.seg.org/doi/book/10.1190/1.9781560801900 Chopra, Satinder, and Kurt J. Marfurt. Seismic Attributes for Prospect Identification and Reservoir Characterization. Society of Exploration Geophysicists, 2007]</ref>]]
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[[File:Curvature_2.JPG|thumb| Three-dimensional quadratic shapes expressed as a function of positive (kpos) and negative (kneg) curvature. <ref name=marfurt>[http://library.seg.org/doi/book/10.1190/1.9781560801900 Chopra, Satinder, and Kurt J. Marfurt. Seismic Attributes for Prospect Identification and Reservoir Characterization. Society of Exploration Geophysicists, 2007]</ref>]]
  
 
== Types of curvature ==
 
== Types of curvature ==
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=== Grabens ===
 
=== Grabens ===
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Similarly to faults, curvature will image the curving slope of the horizon at the fault edges that define the graben.  An example of this is shown in the figure. [[File:Curvature_7.JPG|thumb| (upper a) seismic section with interpretted horizon indicated by a red dotted line. (upper b) time-structure map, with the graben circled (lower a) Dip-magnitude map (lower b) Maximum curvature showing the maximum curvature <ref name=marfurt>[http://library.seg.org/doi/book/10.1190/1.9781560801900 Chopra, Satinder, and Kurt J. Marfurt. Seismic Attributes for Prospect Identification and Reservoir Characterization. Society of Exploration Geophysicists, 2007]</ref>]]
  
 
== References ==
 
== References ==

Revision as of 05:59, 10 October 2017

Curvature is aseismic attributes which is a measure of similarity between waveforms or traces in 2D or 3D seismic volumes. This attribute is designed to emphasize discontinuous events, like faults in structural interpretation . In map view - or time slices - it can also be used to aid in stratigraphic interpretation.

What is curvature?

Geometrically, curvature (k) is defined as the radius of a circle that is tangent to a curve. Mathematically it can be represented as k= 1/r, where k is the curvature, and r is the radius of the circle that is tangent to a curve. The smaller the radius of curvature is, the more bent the curve is. And, if the radius of curvature is infinite, then the curvature (k) would be very small having essentially zero curvature and approximating a straight line.

An illustrated definition of 2D curvature. [1]

Curvature can be calculated in both 2D and 3D, where in 3D it attempts to fit circles, and not just a curve to the surface. A circle with a minimal radius where the curvature is very small and tight would be defined as the maximum curvature (kmax), while a second circle, perpendicular to the first, would have a greater radius than the maximum curvature, and would be defined as the minimum curvature (kmin) for that quadratic, curved surface.

What does curvature reveal about the subsurface?

Curvature is an extremely useful seismic attribute, as it can help us image the shape of features in the subsurface. For instance, anticlinal features would have a positive curvature, while synclinal features would have a negative curvature. Flat features, or those with a constant dipping place would exhibit a curvature close to zero.

Three-dimensional quadratic shapes expressed as a function of positive (kpos) and negative (kneg) curvature. [1]

Types of curvature

Add and discuss Fig 6 from Chopra and Marfurt

Subsurface features identified with the curvature attribute

Many subsurface features can be imaged in 3D seismic with curvature attributes. As with all attributes, the ability to identify features in the subsurface is dependent on the quality of the seismic data. Some of the more common features for which curvature is commonly used are discussed below.

Fractures

Compaction features

Channel edges

Fault edges

Grabens

Similarly to faults, curvature will image the curving slope of the horizon at the fault edges that define the graben. An example of this is shown in the figure.

(upper a) seismic section with interpretted horizon indicated by a red dotted line. (upper b) time-structure map, with the graben circled (lower a) Dip-magnitude map (lower b) Maximum curvature showing the maximum curvature [1]

References

See also

External references

ADD IHS reference

Categories