Paleocurrent Determination by Cross-Bedding and Bedform Interpretation of Borehole Images: Building a Catalog of Reference Cases
ENDERLIN, MILTON B., and DAVID M. RUBIN
One important goal of borehole image analysis is to determine paleocurrent directions. Although borehole imaging technology has achieved such high resolution that small-scale detail can be routinely recorded, the geometric complexity of three-dimensional bedding structures displayed in cylindrical sections makes interpretation extremely difficult. Comparing real borehole images to a catalog of computer-simulated images can aid such paleocurrent assessment.
Reconstruction of bedform morphology from cross-bedding has been the primary
method for paleocurrent determination. Previous computer models of bedform
morphology have generated orthogonal three-dimensional block
diagrams with
associated directional plots of migration vector, cross-bed dips, and bounding
surface dips. To directly compare such
block
diagrams with actual borehole
images, simple techniques have been developed to convert the
block
diagrams into
simulated borehole images. These techniques not only make the orthogonal to
cylindrical coordinate transformation but also allow variable borehole and
bedform size. This approach can be used build a catalog of simulated borehole
images that can be compared with actual images, to facilitate borehole
interpretation.