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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.

CoF@ght 1993, Society ofPe!mlawn Engineers, Inc. This psfxir was pfapamd W Prasantarcm at tha 199S SPE Gas Technology Sympsium held m Calgary, Aibmfa, Canada, 1S-18 March 199S This pspr was selected for~eaentatii by an SPE Program Commrttee following revm'w of informatii corstamad in an abstrsd sulxsitbsd by the authcf( s). Contents of the paper, as pm?a?mted,have not k raviewed by ttw Society of Petroleum Engineers and are subjecl to wrac.tii by the auttvx(s). W material, as presented, does not necessarily reflect any postron of ttsa Scrcisty of Petroleum Enginaera, its offsxrs, or members Papws presented at SPE meetings am aubjad to publiitiem review by Editmial Committees of the Society of Petroleum Engirwars. Elec@xic rejxodudkm, distriiticm, or storage of any pafl of this papsr for cemmercts( purpses Wfscwt tha '#M& consent cd the SocWy of Petroleum Enginaars is pd_ibited Permiss"km to mpmduce h print is restricted to an ebstract of not more than X0 W* illustraticms may not be WPW, The abstract must contain conspicuous adaxnvladgment c+ wtt8ra and by wfvxn the ps$ar was presented. Write Librarian, SPE, PO. E&s SS3S%, R&srdscm, TX 7S9S2-SS26, U.S.A., 1SS01 -972-SS2-9435. AbstractNcn-Darcy flow increases the pressure drop required to establish a desired gas well production rate, thus decreasing productivity. This increased pressure drop is exacerbated by the liquid drop-out and build-up which occurs in gas condensate wells. The additional pressure drop caused by the tw~phase non-Darcy flow can have a dramatic effect on the flowing bottom hole pressure required to maintain producing rates, especially in high rate gas condensate systems. Neglecting or underestimating this effect will cause optimistic predictions of the maintenance of gas rate plateau.Literature values for measured inertial coefficients, (which quanti& non-Darcy flow pressure drops) show a scatter of a one to two orders magnitude for a given permeability. Measurements of inertial coefficients (betas) may or may not agz"ee with literature reported values.Use of literature reported permeability -beta relationships to calculate beta may not be appropriate and may lead to significant errors. These errors increase with increasing flow rate and decreasing permeability.This paper presents transient flow beta measurements obtained in dry core samples and in samples containing different saturations of immobile liquid. Results from core samples from three different reservoirs and one outcrop are included. A method has been developed to estimate the effective beta at different liquid saturations using core samples containing various saturations of solidified paraffin wax that mimic an immobile condensate phase. Continued validation of this technique will allow simplified and inexpensive beta measurements as fimctions of saturation and permeability A relationship has been derived which allows the inertial coefficient to be estimated as a tlmction of effective permeability and effective porosity. This relationship appears to hold for almost all of the core sa...

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