--> Abstract: Methods for the Determination of the Clay and Nonclay Mineralogical Content of Reservoir Sandstones, by R. E. Hughes and D. M. Moore; #91013 (1992).

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ABSTRACT: Methods for the Determination of the Clay and Nonclay Mineralogical Content of Reservoir Sandstones

HUGHES, RANDALL E., and D. M. MOORE, Illinois State Geological Survey, Champaign, IL

Whether for the purpose of increasing petroleum production or understanding geological history, determination of the mineral content of a reservoir is critical. We use x-ray diffraction (XRD) methods to assess these mineral contents. High-quality determinations require: (1) a random pack of properly ground particles, (2) an accurate measurement of the bulk clay mineral content, and (3) quantifying of individual clay minerals. New grinders yield the uniformly ground samples needed to ensure randomly oriented powder packs. Nonclay minerals are measured by comparison of XRD peak areas from standards with data from unknowns. Bulk clay content is estimated from the area of the 020 XRD peak of clay minerals. However, large errors are caused by variable intensities of the 020 peaks of indivi ual clay minerals and the low 020 intensity in many samples. Clay content also can be estimated by measuring hydroxyl weight loss during heating or point counting with a microprobe. Amounts of individual clay minerals are determined by comparing peak intensities of unknowns with those calculated from NEWMOD{TM}. Variations in the size of individual clay particles, clay minerals contained within carbonates and quartz overgrowths, and poor resolution of clay XRD peaks cause most errors. Errors are minimized by our current procedure:
A. Bulk- 2 g <0.5 mm sample goes to micronize, goes to bulk pack XRD, goes to peak areas.
B. Clay Minerals- 2 g <5 mm sample, goes to laundry bleach (100 degrees C), goes to acetic acid, goes to ultrason, goes to screen to <44 micrometers, goes to size 3 times to <16 micrometers, goes to centrifuge, smear slide, XRD, goes to peak areas.

 

AAPG Search and Discovery Article #91013©1992 AAPG Eastern Section Meeting, Champaign, Illinois, September 20-22, 1992 (2009)