Measurement Parameters and Resolution Aspects of Micro X-ray Tomography for Advanced Core Analysis

Micro X-ray Tomography (μ-XCT) is an emerging non-destructive imaging technology with large potential for application in advanced core analysis. This scanning technique provides 3-D images and quantitative information in the micron range, i.e. at pore scale level. μ-XCT will assist to gain fundamental insight on rock topology structure, in-situ physicochemical processes as well as grain contacts and micro-fractures. Especially in the Carbonate arena (e.g., Middle East), where pore structures are extremely complex, μXCT can provide a step change in our understanding of multi-phase flow properties of rock. The knowledge gained will lead to more accurate scaling relationships between microand macro(field) scales enabling better estimation of hydrocarbon recovery. Tabletop μ-XCT scanners are envisaged to provide optimal flexibility for advanced core analysis research. In this paper we discuss the various measurement parameters that play a role in μ-XCT. Signal-to-noise ratio and spatial resolution are considered as the most important parameters for μ-XCT. Some results will be presented of an assessment study towards the performance capabilities of a number of tabletop μ-XCT scanners. In this study different reservoir carbonate rock samples as well as synthetic rock samples have been used. The spatial resolution of current commercial tabletop μ-XCT scanners is in the order of 5-8 microns, which is not sufficient to probe micro pores for carbonate rock. We have also considered technical innovations to enhance the spatial resolution in tabletop μXCT. Possibly the spatial resolution in μ-XCT can be improved using nano-focus X-ray sources with sub-micron focal spot. Further improvement in spatial resolution is expected from using emerging tabletop laser plasma X-ray technology. For applications in tight carbonates, synchrotron beam line based μ-XCT offers spatial resolutions below 1 micron.