Holographic 3-D laser imaging into sandstone

Abstract

With a novel imaging technique that uses holographic recording and reconstruction to perform laser-ranging into translucent media, we have imaged several grain layers into a sandstone sample. Three-dimensional microscale (10 micron lateral and 30 micron depth resolution) information on grain size and geometry was obtained as deep as 400 microns into the sample without thin-sectioning. Surficial grain features in the holographic reconstruction were associated with features observed using conventional optical and scanning electron microscopy. This imaging technique represents a new form of nondestructive evaluation of grain and pore structure in reservoir rock by acquiring full-field images at variable depths, unlike sequential scanning microscopy that requires tomographic reconstruction.