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Transforms to enhance correlation of mechanical well logs (1975)

Robinson, J. E.

Springer

Mathematical geology 7 (1975), S. 323-334

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ISSN: 1573-8868

Keywords: crosscorrelation ; stratigraphy

Source: Springer Online Journal Archives 1860-2000

Topics: Geosciences , Mathematics

Notes: Abstract Mathematical correlation of geologic sections from mechanical well logs depends on comparison of frequency components derived from the recorded amplitude variations of the well logs as they respond to changes in lithology. Techniques have been developed that compensate for changes in thickness of units within lithologic sequences and for moderate numbers of missing and truncated beds. However, accurate correlation depends on time stratigraphic units being composed of relatively consistent sequences of rock lithologic units. Correlation is uncertain in areas where time stratigraphic sequences exhibit considerable facies variation. Visual correlation experiences similar problems but the human eye can sort out facies changes more easily and may be better than mechanical correlation in problem areas. Both mechanical and visual correlation can be enhanced by the application of relatively simple transforms to the basic log data. They are applied by computer to digital logs and are designed to magnify specific diagnostics of the more continuous beds while subduing distracting events and noise. Both mechanical and visual correlation are improved by the use of transformed logs; moreover, the digital logs permit optically pleasing displays that maintain the overall advantage of trained geologists over mechanical intervention.

Type of Medium: Electronic Resource

URL: http://dx.doi.org/10.1007/BF02081704

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Estimation of nitrogen-15 levels in derivatized amino acids using gas chromatography quadrupole mass spectrometry with chemical ionization and selected ion monitoringAbbreviation: HFBA = heptafluorobutyric anhydride. (1978)

Robinson, J. R. ; Starratt, A. N. ; Schlahetka, E. E.

Chichester : Wiley-Blackwell

Biological Mass Spectrometry 5 (1978), S. 648-653

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ISSN: 0306-042X

Keywords: Chemistry ; Analytical Chemistry and Spectroscopy

Source: Wiley InterScience Backfile Collection 1832-2000

Topics: Chemistry and Pharmacology

Notes: The data indicate that a commercial, low resolution mass spectrometer can be used with chemical ionization and selected ion monitoring, without a data system, to estimate nitrogen-15 isotopic enrichment with a sensitivity and precision adequate for many biological studies. This was demonstrated using derivatized amino acid mixtures with separation and direct introduction into the mass spectrometer via a gas chromatograph. The method can discriminate between mean levels separated by 0.1 atom % 15N with 68% confidence at the 0.1 nmol level. Labeled dansylamide samples, inserted by probe, were also measured for 15N content.

Additional Material: 3 Ill.