Oil-shale analysis by CP/MAS-13C n.m.r. spectroscopy

✍ Scribed by Edward W. Hagaman; Donald C. Cronauer; Fred M. Schell

• Publisher: Elsevier Science
• Year: 1984
• Tongue: English
• Weight: 613 KB
• Volume: 63
• Category: Article
• ISSN: 0016-2361
• DOI: 10.1016/0016-2361(84)90309-0

✦ Synopsis

Solid-state 13C n.m.r. (CP/MAS-13C n.m.r.) spectroscopy provides a direct method for estimating potential oil yields of oil shale formations. Relative aliphatic resonance areas correlate linearly with oil yield and provide a method for oil yield estimation that obviates the need to determine weight per cent organic carbon for each specimen. Thisdirect measurement is performed using an internal area standard, the carbonyl resonance of N-(2-'3C-propanonyl)-N,N,N-trimethylammonium chloride, to monitor spectrometer sensitivity. Oil shale samples obtained as a function of depth at a site in the Mahogany Zone of the Green River Formation show a near-constant aliphatic carbon fraction, f,,_(l -f,), and a twofold, nonlinear variation in oil yield over the vertical dimension of the sampling. Aliphatic carbon resonance band shape changes among these samples are interpreted qualitatively as reflecting a two component mixture composed of the condensed alicyclic structures which link together to form the kerogen matrix and an n.m.r.-distinct but not necessarily chemically distinct contribution from normallong chain hydrocarbon residues.