AAPG GEO 2010 Middle East
Geoscience Conference & Exhibition
Innovative Geoscience Solutions – Meeting Hydrocarbon Demand in Changing Times
March 7-10, 2010 – Manama, Bahrain
3D Microanalysis of Geological Samples with Nanofocus Computed Tomography
(1) GE Sensing & Inspection Technologies, Wunstorf, Germany.
During the last decade, Computed Tomography (CT) has progressed to higher resolution and faster reconstruction of the 3D-volume. Most recently it even allows a three-dimensional look inside of geological samples with submicron resolution. This allows sophisticated analysis of hydraulic parameters like porosity and permeability or volumetric information about distribution and quantitative content of specific minerals providing important information for petrophysicists.
In recent years major steps in important hardware components like open microfocus or even nanofocus X-ray tube technology on the one side and the development of highly efficient and large flat panel detectors on the other, allowed the development of very versatile and high resolution commercially available laboratory CT systems like the nanotom®. Electromagnetic focusing of the electron beam allows generating X-ray beams with an emission spot diameter down to well below one µm which is essential for CT examination with voxel-sizes in the sub-micron range. These characteristics with respect to spatial resolution principally allow CT measurements that can compete with many absorption contrast setups at synchrotron radiation facilities.
The paper will compare CT results of sophisticated conventional tube-based with synchrotron radiation based scans and showcase several geological applications which were performed with the nanotom, the first 180 kV nanofocus CT system tailored specifically for highest-resolution scans of samples up to 120 mm in diameter and weighing up to 1 kg with exceptional voxel-resolutions down to <500 nm (<0.5 microns). In order to cover the widest possible range of samples, the system is equipped with the first commercially available 180kV/15W high power nanofocus tube. This source can be operated in four different modes. The so-called nanofocus mode provides an X-ray spot size of down to approximately <0.9 µm which can be used for highest resolution CT scans with submicrometer voxel size. On the other hand the high power mode (up to 15 Watts at the target) has enough penetration power to examine high-absorbing samples.