Pore structure determination using confocal scanning laser microscopy

A methodology is presented that shows how Confocal Scanning Laser Microscop y (CSLM) can be used to measure the microscopic three dimensional distribut ion of pore bodies and pore throat size in sandstones with hydrocarbon rese rvoir potential. The technique involves injection of doped epoxy into the s ample pore space, followed by non-destructive serial sectioning of the rock using laser light. Fluorescence imaging combined with image thresholding t echniques allows the pore volume structure of the sample to be reconstructe d to a depth of > 500 microns. The main problems encountered during experim entation were degraded depth resolution and laser attenuation both of which contributed to inaccuracies in the sample image. Using a method of 'point- wise thresholding' these technical difficulties can be overcome, allowing a highly accurate volume reconstruction to be made. Accounting fully for las er attenuation will in principle allow a reduction in the amount of injecte d fluorochrome concentration, and thus deeper depth penetration and imaging of the sample. Euclidean distance maps are suggested as a means of address ing the shortcomings in classical medial axis transforms for application to connectivity investigations. (C) 1999 Elsevier Science Ltd. All rights res erved.