Petrographic X-Ray Diffraction (XRD) Analysis

X-Ray Diffraction (XRD) allows assessment of clay types and clay volumes that cannot be determined by Thin Section or SEM analysis. Bulk and Glycolated Clay XRD analysis also provides:

Whole rock mineralogy and clay fraction mineralogy
Allows comparison of XRD mineralogy and mineralogy calculated from thin section analysis
Presence / absence of key minerals and risks (such as swelling clays and / or acid soluble minerals)

XRD analysis should not be used as a substitute for statistical thin section petrology or scanning electron microscopy. For example, bulk XRD analysis can not differentiate between quartz types (monocrystalline, chert, cements, etc.) and therefore cannont be used solely for reservoir characterization. In any petrographic study, a small subset of samples may be selected for XRD analysis if either prior examination (such as thin section petrology or SEM analysis) suggests it will provide useful data.

Diffractograms shown the bulk sample (red) and clay fraction (blue). Note how the clay fraction (blue) shows much larger peaks for the clays, which allows more precise determination of their relative abundances.