Application of Curvature Attributes to Kansas Subsurface Data

Timothy R. Carr¹ and Susan E. Nissen². (1) Kansas Geological Survey, 1930 Constant Avenue, Lawrence, KS 66047 (2) Consultant, McLouth, KS [email protected]

The advent of digital data and the interpretation workstation have allowed the generation and analysis of large quantities of subsurface data. Today, numerous types of maps from geologic, geophysical, and engineering data (e.g., structure, isopach, isochron, and reservoir pressure maps) can be produced simply by pressing a few buttons. Some of these maps are straightforward, while others are of attributes that may seem rather obscure to the casual interpreter. One of the less commonly used attributes is curvature; however, it is possible to extract significant new insight from the digital data with the application of curvature attributes. Curvature attributes go beyond dip and azimuth attributes and are closely related to the second derivative of the surface. Curvature attributes have a relatively long history in such areas as medicine, optics, and terrain analysis. Curvature is a two- or three-dimensional property of a curve or plane that describes how bent it is at a particular point.

Examples of the power of curvature analysis of surfaces and 3D volumes will be demonstrated using several types of data from Kansas. These examples include

á   Using regional gravity and magnetic data to map basement faults in small areas across central Kansas and identifying the relation between the faults and existing production;

á   Applying volumetric curvature analysis to traditional 3D seismic data to highlight open and closed solution-enhanced fractures beneath the MississippianÐPennsylvanian unconformity and determining the relation between the fractures and fluid production (oil and water); and

á   Mapping with a large number of stratigraphic tops in southwest Kansas to delineate pressure compartments in the Hugoton Gas Area.