Macro Imaging of Rock Cores: Preparation, Approach, and Usefulness

HIPKE, WESLEY, and W. E. FULL, Wichita State University, Wichita, KS

Petrographic image analysis (PIA) has extracted useful data from rock thin sections taken from rock cores. These data include porosity, permeability, and recovery potential. The usual procedure is to analyze images of rock thin sections viewed through a microscope using frame-grabbing hardware and software, which are then processed using a wide array of statistical/deterministic algorithms. The results are functions relating: the imaged parameters to rock petrophysics; the definition of diagenetic classification schemes; or even the foundation for definition of chaos functions describing 3-D pore networks. Normally, only the pore network serves as input into the approach previously described.

On the macro scale, however, a different collection of images is used as input. The procedure involves imaging sections of polished rock core which represent areas as small as 2 x 2 in. or as large as 5 x 5 in. The variability observed normally on this scale includes large pores, fractures, bedding structures; in carbonates it includes mineralogy changes, fossil content, and various types of textures. The ability to differentiate any of these characteristics depends generally on the quality of hardware (resolution) and the ability to partition the rock image by defining colors or patterns. To increase discrimination power the rock slab should be stained and the pores and fractures enhanced. Examples of processing carbonate cores will be presented. Problems and the overall usefulness o the macro approach to core analysis for reservoir analysis will also be highlighted.

AAPG Search and Discovery Article #91008©1991 AAPG Mid-Continent Section Meeting, Kansas Geological Society, Wichita Kansas, September 22-24, 1991 (2009)