Structural Curvature / Paleo-Curvaturetm

Curvature is a measure of shape that characterizes the deviation of a surface from a plane. In seismic data, curvature exposes stratigraphic and structural flexures that can be indicative of geologic processes.

OpenGeoSolutions has developed fast, accurate algorithms for deriving volumetric curvature for a spectrum of spatial scales from local through regional. Curvature attributes include Kdip, Keuler, Kgauss, Kmax, Kmean, Kmin, Kneg, Kpos, Krot, Kshape, Kstrike and Ktotal.

Contrasting present day curvature (Structural Curvature) with curvature calculated on data flattened to a geologic compensation level (Paleo-Curvaturetm) can provide insights into stratigraphy and differential compaction. The curvature images shown below are co-rendered with Spectral Discontinuitytm.

 

Paleo-Curvaturetm                                                        Structural Curvature

(Data Courtesy of Nexen Energy ULC)

 

Differential Curvaturetm   

Structural geologists traditionally determine the rotation of dip and azimuth between strata via a graphical approach using stereonets. For a sample by sample calculation of the structural rotation that has occurred between two seismic horizons, a computation approach is more efficient. However, structural dip and azimuth themselves are merely measures of the spatial derivatives of a surface and curvature is a function of the first and second spatial derivatives of this surface. By extension, Differential Curvaturetm as a measure of changes in structure that have occurred during the time interval between the deposition of two seismic events, can be easily determined from the sample by sample dip / azimuth rotation that has occurred over that same time period.

In this example we show;

  • Kpos (alpha=-0.3) Structural Curvature at the Lower Keg River horizon, Kpos (alpha=-0.3)
  • Paleo-Curvaturetm at the Lower Keg River horizon and Kpos (alpha=-0.3)
  • Differential Curvaturetm between Lower Keg River and the shallower Jean-Marie horizon.

Differential Curvaturetm can be used to work out the timing of post Lower Keg River deformation.

 

Structural Curvature

 

Paleo-Curvaturetm

 

Differential Curvaturetm

 

(Data Courtesy of Nexen Energy ULC)