Last year, the X27A beamline at the National Synchrotron Light Source (NSLS) became dedicated solely to X-Ray Computed Microtomography (XCMT). This is a third-generation instrument capable of producing tomographic volumes of 1-2 micron resolution over a 2-3mm field of view. Recent enhancements will be discussed. These have focussed on two issues: the desire for real-time data acquisition and processing and the need for highly monochromatic beam (.1 % energy bandpass). The latter will permit k-edge subtraction studies and will provide improved image contrast from below the Cr (6 keV) up to the Cs (36 keV) k-edge. A range of applications that benefit from these improvements will be discussed as well. These two goals are somewhat counterproductive, however; higher monochromaticity yields a lower flux forcing longer data acquisition times. To balance the two, a more efficient scintillator for X-ray conversion is being developed. Some testing of a prototype scintillator has been performed; preliminary results will be presented here. In the meantime, data reconstruction times have been reduced, and the entire tomographic acquisition, reconstruction and volume rendering process streamlined to make efficient use of synchrotron beam time. A Fast Filtered Back Transform (FFBT) reconstruction program recently developed helped to reduce the time to reconstruct a volume of 150 x 150 x 250 pixels 3 (over 5 million voxels) from the raw camera data to 1.5 minutes on a dual R10,000 CPU. With these improvements, one can now obtain a "quick look" of a small tomographic volume (~l0 6 voxels) in just over 15 minutes from the start of data acquisition.

Synchrotron X-ray computed microtomography (CMT) was applied to five basalt samples from different locations in order to determine the microgeometrical structures and physical properties of vesicles. Two vesiculated basaltic lavas and one calcite-filled vesiculated basaltic lava were collected from the Lesotho Highland, South Africa, and two basaltic scoria tephra were taken from the Lungkuan Volcano Group in northeast China. They were examined with CMT on the X27C beam line of the Brookhaven National Synchrotron Light Source. The voxel size varied from 10 to 20 µm depending on the chosen field of view of the tomographic instrument. A fast-filtered back-transform (FFBT) algorithm was employed in the tomographic reconstruction. A 3D image geometry analysis package was used to measure the vesicularity, specific surface area and interconnectivity of the vesicles. The results of the analyses showed that the bubbles have roughly spheroidal forms of different sizes. Vesicularity ranged from 45% for lavas to 80% for scoria. At least 90% of the vesicles are interconnected. Specific surface area was determined both by counting voxel faces and by use of two-point correlation functions.

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M.E. Coles, SPE, R.D. Hazlett, and E.L. Muegge, Mobil E& P Technical Center, K.W. Jones, B. Andrews, B. Dowd, P. Siddons, and A. Peskin, Brookhaven National Laboratory, P. Spanne, European Synchrotron Facility, W.E. Soll, Los Alamos National Laboratory Abstract High resolution computed microtomography (CMT) using synchrotron X-ray sources provides the ability to obtain three-dimensional images of specimens with a spatial resolution on the order of micrometers. Microimaging capabilities at Brookhaven National Laboratory's National Synchrotron Light Source have been enhanced to provide larger and higher resolution 3-D renderings of pore networks in reservoir rocks at a fraction of the time required in previous first generation scanning methods. Such data are used to model single and multiphase flow properties in digital images of real porous media. Pore networks are analyzed for tortuosity and connectivity measures, which have been elusive parameters in transport property models. We present examples of porosimetry simulation via network modeling to produce initial water saturation and residual oil distributions in a water-wet pore system. Furthermore, pore networks can provide the boundary condition framework for more rigorous simulations of displacement, such as in the lattice Boltzmann simulated waterflood example provided. Direct comparison between simulation and experiment is also possible. CMT images of a 6 mm subsection of a one inch diameter reservoir core sample were obtained prior and subsequent to flooding to residual oil. The fluid distributions from CMT, lattice Boltzmann waterflood simulation, and percolation-based network modeling were found to be highly correlated. Advances in 3-D visualization, implemented in Brookhaven National Laboratory's 3-D theater, will allow even greater digestion and interpretation of phenomena dependent upon pore interconnectivity and multipore interactions. Introduction Computed Microtomography (CMT) has been available at the National Synchrotron Light Source (NSLS) at Brookhaven National Laboratory for many years. First generation scanning methods gave high resolution images of geological and biological samples approaching 1 m resolution. First generation scanning provided necessary detail in moderate to high permeability porous media samples for transport property modeling with computational fluid dynamics methods. The time requirements of first generation methods limited the number of samples which could be investigated and restricted the potential of in-situ experimental monitoring. Implementation of array detection technology enables acquisition of larger 3-D volumes at a fraction of the time required in first generation scanning. Initial implementation, however, was limited by the resolution of fluorescing elements of the detector material, on the order of 10 m rather than 1 m. With the introduction of expansion optics, images of 2.7 m resolution have been obtained containing in the neighborhood of 3x 107 voxels. Improvements in data acquisition, transmission, and reconstruction have reduced the time requirements to produce such a volume to a few hours. Herein we document the status of CMT at the NSLS and display a variety of applications using both first generation and state-of-the-art image data on reservoir rock samples. Advances in Imaging A schematic of the CMT apparatus is provided as Figure 1, X-ray CMT produces a cross-sectional map, or slice, of linear x-ray attenuation coefficients inside a small sample. To obtain the data for a reconstructed slice, the x-rays transmitted through a single slice of the sample are recorded on a linear array of detectors. The sample is rotated, with the axis of rotation perpendicular to the plane of the incident beam, by a discrete angular interval determined by the linear resolution desired. The transmission of each ray through the sample, along a line from the source to the detector is recorded; this represents a line integral of the attenuation coefficients along this ray. The procedure is repeated for each angular view until the sample has been rotated by 180 in the x-ray beam. P. 413

High resolution computed microtomography (CMT) with synchrotron X-ray sources provides the ability to obtain three-dimensional (3D) images of specimens with a spatial resolution on the order of micrometers. Microimaging capabilities at Brookhaven Natl. Laboratory's Natl. Synchrotron Light Source have been enhanced to provide larger and higher resolution 3D renderings of pore networks in reservoir rocks at a fraction of the time required in previous first generation scanning methods. Such data are used to model single and multiphase flow properties in digital images of real porous media. Pore networks are analyzed for tortuosity and connectivity measures, which have been elusive parameters in transport property models. We present examples of porosimetry simulation through network modeling to produce initial water saturation and residual oil distributions in a water-wet pore system. Furthermore, pore networks can provide the boundary condition framework for more rigorous simulations of displacement, such as in the lattice Boltzmann simulated waterflood example provided. Direct comparison between simulation and experiment is also possible. CMT images of a 6-mm subsection of a 1-in. diameter reservoir core sample were obtained before and after flooding to residual oil. The fluid distributions from CMT, lattice Boltzmann waterflood simulation, and percolation-based network modeling were found to be highly correlated. Advances in 3D visualization will allow even greater digestion and interpretation of phenomena dependent upon pore interconnectivity and multipore interactions.