SPE Members Abstract The value of Computed Tomography (CT) to analyze fluid flow in porous media has been verified, using a medical CT system. A series of simple displacement experiments using Danian chalk and Berea sandstone are presented to prove the feasibility of this concept. Radial and axial cross sectional views of the cores show movement of fluid fronts and changes in saturations at fixed locations. The limitations of the medical computer software provided with the first generation CT system used in provided with the first generation CT system used in this study are discussed and some possible enhancements of the equipment and software are proposed. Introduction Computed tomography (CT) is a method for obtaining computer enhanced X-ray photographs of cross-sectional slices of an object. Tomography is derived from the Greek word, tomos, meaning section. The technique involves rotating an X-ray source and diametrically opposed detector (or a fixed series of detectors may be used) synchronously about the object to be observed. CT scanning was developed by Godfrey Hounsfield and Allen Cormack during the early 1970's and resulted in their receiving the Nobel Prize in 1979. As originally developed, the technique has been widely used in diagnostic medicine to observe internal organs and tissues. However, the range of potential applicability is much broader. As first potential applicability is much broader. As first demonstrated by Wang et al., CT can be utilized for core analysis and studies of fluid flow and enhanced recovery mechanisms. This paper documents a series of experiments designed to demonstrate the capabilities of a medical CT system and to point out equipment and software modifications that would enhance its core analysis capabilities. These experiments are qualitative rather than quantitative and are meant only to demonstrate the potential for CT scans in core analysis. In this work, Danian chalk and Berea sandstone cores were saturated with various fluids and several cross-sectional images were constructed using the CT system. The fluid front and the relative saturations of the phases at a fixed location in the core were observed as the front was displaced. The capabilities for use of the system for X-ray microanalysis were not demonstrated. Due to the speed of the equipment (about 8 sec. per section), it is possible to closely monitor per section), it is possible to closely monitor fluid saturation changes occurring in the rock pores and possibly discriminate between proposed displacement mechanisms. This technology yields the potential for quantifying porosity, fluid potential for quantifying porosity, fluid saturations and sweep efficiencies as well as monitoring changes occurring on rock surfaces such as adsorption and swelling. EXPERIMENTAL EQUIPMENT The equipment used consisted of a first generation CT system and associated software. A tungsten anode emitted X-ray photons with an energy of 130 kV. A slice width of 2 mm resulted in greatest resolution for this system. The X-ray attenuation factors or "densities" are in Hounsfield units (H.U.) and are presented in Table 1 for various media. These units are calculated using the following equation: (1) where gamma = X-ray attenuation of material gamma w = X-ray attenuation of water.