Articles | Volume 22
Sci. Dril., 22, 35–42, 2017
Sci. Dril., 22, 35–42, 2017

Technical development 31 May 2017

Technical development | 31 May 2017

A comparison of the use of X-ray and neutron tomographic core scanning techniques for drilling projects: insights from scanning core recovered during the Alpine Fault Deep Fault Drilling Project

Jack N. Williams1, Joseph J. Bevitt2, and Virginia G. Toy1 Jack N. Williams et al.
  • 1Department of Geology, University of Otago, PO Box 56, Dunedin 9054, New Zealand
  • 2Australian Centre for Neutron Scattering, Australian Nuclear Science and Technology Organisation, Lucas Heights NSW 2234, Australia

Abstract. It is now commonplace for non-destructive X-ray computed tomography (CT) scans to be taken of core recovered during a drilling project. However, other forms of tomographic scanning are available, and these may be particularly useful for core that does not possess significant contrasts in density and/or atomic number to which X-rays are sensitive. Here, we compare CT and neutron tomography (NT) scans of 85 mm diameter core recovered during the first phase of the Deep Fault Drilling Project (DFDP-1) through New Zealand's Alpine Fault. For the instruments used in this study, the highest resolution images were collected in the NT scans. This allows clearer imaging of some rock features than in the CT scans. However, we observe that the highly neutron beam attenuating properties of DFDP-1 core diminish the quality of images towards the interior of the core. A comparison is also made of the suitability of these two scanning techniques for a drilling project. We conclude that CT scanning is far more favourable in most circumstances. Nevertheless, it could still be beneficial to take NT scans over limited intervals of suitable core, where varying contrast is desired.

Short summary
We compare images of drillcore from the Alpine Fault in New Zealand that were collected using X-ray computed tomography (CT) and neutron tomography (NT). Both techniques provide 3-D images of the core's internal structure, which would not be possible through visual analysis alone. We find that CT scans are more beneficial, as they can image a wider range of rock types, and this scanning technique is more practical. Nevertheless, NT provides complementary scans over limited intervals of core.