ABSTRACT: Anisotropy and Computer Mapping--Reading Between the Lines

Jeffrey M. Yarus, Grigory Kushnir

Geologic data is commonly anisotropic, the property of having a preferred direction of correlation. Faulted surfaces, anticlines, synclines, and elongated marine bars are some of the simpler geologic features that exhibit anisotropy. More complex surfaces include porosity and permeability. Point data collected from such surfaces comprise mapping variables that are assumed to be more or less "regionalized." In many instances, the sample density and distribution are irregular, further complicating interpolation. Manual contouring can be difficult and requires local experience in a given area. Machine contouring of such data is more difficult, requiring not only local experience, but also a familiarity with gridding and neighborhood theory.

One way in which to increase the precision of computer mapping is by using ancillary information about the anisotropic properties of the surface. This can include qualitative (indicator) and quantitative information from sources such as seismic data, better controlled shallower horizons, and general geologic history. Using anisotropic information in the process of computer mapping results in honoring not only the primary data, but also the overall geologic interpretation. This paper describes the results of computer mapping using all available information about anisotropy. Kriging and non-Kriging methods are discussed and results using both theoretical and real surfaces are given.

AAPG Search and Discovery Article #91002©1990 AAPG Rocky Mountain Section Meeting, Denver, Colorado, September 16-19, 1990