DETERMINATION OF POROSITY STRUCTURE IN CROSS-TROUGH LAMINATED SANDSTONES USING COMPUTED MICROTOMOGRAPHY

Computed X-ray microtomography (CMT) was used to reconstruct 3-dimensional images of the porosity for three field-oriented samples of fine to medium-grained, micaceous, cross-trough laminated sandstone from the Towaco Formation (Newark Supergroup) in New Jersey. CMT analysis was done using beamline X27a at the National Synchrotron Light Source, Brookhaven National Laboratory. Standard petrographic and volumetric calculations of porosity for these samples agree with the values obtained by CMT techniques. Digital CMT images, with resolutions between 3.4 and 6.8 microns, allow us to quantify the spatial distribution, shape, orientation and connectivity of porosity for these sandstones. Preliminary results indicate that these microscopic porosity characteristics correlate strongly with the type, scale and orientation of macroscopic cross-lamination features. Understanding the correlation between micro-porosity structure and macroscopic sedimentary structure will allow us to better predict fluid flow anisotropy based on macroscopic features.