Interlaboratory Comparison of Thin Section Epoxy Impregnation Procedures

Michael D. Wilson, Alan P. Byrnes

Evidence of ineffective blue-dye epoxy impregnation is encountered all too commonly in thin sections. A study involving ceramic disks was conducted to compare the efficiencies of a variety of epoxy impregnation procedures used by major laboratories. Disks were sent to five commercial and four major oil company thin section laboratories which then impregnated the disks and returned them for analysis. Porcelain disks were used because of their high degree of uniformity, white color, rock-like composition and pore geometry, uniform pore size, and high pore connectivity.

Impregnation efficiency was determined by calculating the pore volume invaded using helium porosimetry and by determining the areas and distances of invasion based on extent of blue-dye invasion in cross-sectional cuts through the disks. Techniques which proved very highly effective are vacuum or vacuum/pressure impregnation in which the epoxy was added to the sample container subsequent to evacuation. Relatively ineffective are vacuum techniques, at room or elevated temperatures, where the sample is submerged in epoxy prior to evacuation. The key to effective impregnation is to remove air from the sample before it is covered by epoxy. Factors which have little or no influence on the effectiveness of impregnation include type of blue dye, epoxy type, and presence of fluorescent dye. H gh-quality thin sections can be prepared using less-effective techniques if care is taken to prepare them from the outer edge of the impregnated sample.

AAPG Search and Discovery Article #91038©1987 AAPG Annual Convention, Los Angeles, California, June 7-10, 1987.