2019 AAPG Annual Convention and Exhibition:

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Long-Wave Infrared Core Imaging for Oil and Gas Applications

Abstract

Traditionally, imaging spectroscopy has been focused on the visible - near infrared (VNIR) and short-wave infrared (SWIR) segments of the electromagnetic spectrum. While of undoubted value, these wavelength ranges cannot identify anhydrous silicate and sulfate phases and the information generated can be hampered by low reflectance in dark and fine-grained lithologies. We have developed a core imaging workstation that combines a long-wave infrared (LWIR) hyperspectral camera with a SWIR hyperspectral camera and a high resolution RGB line scan camera. The LWIR hyperspectral camera measures 96 bands of high quality spectral information between 8 and 12 microns at a spectral resolution of ~100nm. Both the hyperspectral cameras have a spatial resolution of 0.4mm, while the RGB camera has a resolution of 0.12mm. The LWIR records fundamental absorption features related to a bonds between oxygen and a variety of cations, which allows for identification and mapping of anhydrous silicates, with quartz and feldspar the most important for oil & gas applications. In addition, the LWIR allows for mapping of anhydrous sulfate minerals, and enhanced identification and mapping of carbonates and other unconventional cores, especially in dark and fine-grained lithologies. The combination of LWIR and SWIR therefore provides a powerful tool for a wide range of minerals. In addition to mineral identification, the LWIR is sensitive to changes in the particle size of minerals, especially quartz and carbonate. We describe the processing routines we have developed to capture these variations and demonstrate how they provide important information as to the nature of minerals (i.e. sediment vs. cement), and how these data can be applied to sedimentary and sequence stratigraphic studies.