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.

AAPG Search and Discovery Article #91021©1997 AAPG Annual Convention, Dallas, Texas.