Accurate measurements and high resolution three-dimensional displays of pore geometry have been achieved using sophisticated optics, three-dimensional image analysis, and techniques of computer tomography. These new methods allow detailed analysis of low permeability pore structures with isolated secondary porosity. Examples under study include Cotton Valley tight gas sands, Smackover carbonates, and Whitestone limestone.

The procedure is to "serially section" rock samples, either by successive 2µm grindings or by microtoming brominated-epoxy/epoxy "double pore-casts." SEM images or photomicrographs of the sections are digitized, and these successive images are reconstructed into three-dimensional data sets. These data sets are then

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analyzed for such parameters as grain size and shape, pore volume, connectivity, and permeability.

Computer graphic displays are generated using techniques developed for biomedical applications. Colored images of the reconstructed three-dimensional pore structures are photographed from many viewing angles. These multiple views are combined by a special lens-mirror optical imaging system to produce "parallax panoramagrams" which show 20° of "rotation." Panoramagrams provide high resolution, high magnification displays which can be viewed with the naked eye, without special equipment.

State-of-the-art computer graphics, research quality optics, and new image analysis techniques have been used to provide a rigorous approach to understanding pore geometry. This novel synthesis shows particular potential for the study of hitherto intractable, complex structures.

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