Hyperspectral Imaging, XRF and High Resolution Scanning: The Key to Quick Accurate Core Analysis

Abstract

The oil sand deposits of NE Alberta, Canada, have been evaluated in the past using up to 32 well cores per section. Each core is slabbed, logged and described by a geologist with depth corrected photographs. Destructive analysis follows to determine the bitumen saturation, clay mineralogy, and grain size distribution present. This entails spot sampling for XRD analysis and thin sections made to determine the presence of clays. Also a few samples are collected for Laser Coulter/sieving to resolve the grain size distribution. To complete all these analyses can take months, be costly, and are not repeatable or statistically relevant.

Recent research has found that hyperspectral imaging merged with X ray fluorescence and high resolution photography significantly speeds up the process, generates statistically relevant and repeatable datasets at resolutions unattainable previously due to the cost and time needed for processing. The technology uses scanners mounted on tracks which image the slabbed core from millimeters a way, generating half millimeter pixel data across the core in the near infra red part of the spectrum (920 to 2520 nm), and XRF measurements (Na to Fe) at 2.5cm sampling intervals. A digital camera is also used on the same track assembly to photograph down to a resolution of 5 microns, though the normal resolution is 44 microns – below the cut off for the finest sand grain size. A new core scanning XRF system, using Helium atmospherics, can also resolve clay types including the presence of swelling clays containing sodium atoms. Overall for a 10 meter core, about 11 GB of information is produced so that big data techniques have to be utilised during processing.

Generated output curves include bitumen saturation, porosity, grain size, sorting, mineralogy, and net to gross. Furthermore, the bitumen in the core can be electronically removed to reveal hidden sedimentary structures and trace fossils in what would previously be described as ‘massive sandstone’. Also the exact locations of any secondary tests on the A side core, such as bitumen geochemical analysis and ESEM studies, are recorded. The B side of the core can now be submitted to the Alberta Government in pristine condition. If not required for preservation, the core can be destroyed, saving significant storage costs for the operator.

This new technology dataflow can fully analyse a core in under a week and is significantly cheaper than previous lab-based analyses.

AAPG Datapages/Search and Discovery Article #90323 ©2018 AAPG Annual Convention and Exhibition, Salt Lake City, Utah, May 20-23, 2018