Studies on 1H-relaxation and free radicals in kerogen

Bakr, M.; Aoki, Masahiko; Sanada, Yuzo; Yokono, Tetsuro

doi:10.1016/0016-2361(88)90278-5

Cited by 4 publications

(2 citation statements)

References 6 publications

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“…As shown by investigations, not only oils and bitumoids themselves, but also their heterocyclic components such as asphaltenes, asphaltogenic acids, and resins (benzene, benzene-alcohol) are carriers of genetic information, due to which they were used for oil survey, extraction, and processing and also in theoretical studies [16][17][18][19]. Current procedures allow one to isolate these components as polycrystalline solids; investigation of their EPR spectra precludes the dependence of the line width and shape on the sample viscosity, which makes it possible to observe the more informative anisotropic spectra at room temperature and thus to obtain more reliable results, especially when evaluating the concentration of the paramagnetic centers.…”

Section: Introductionmentioning

confidence: 99%

EPR spectra of V(IV) complexes and the structure of oil porphyrins

Gilinskaya

2008

J Struct Chem

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For natural bitumoids, the effects of the structure of vanadyl-porphyrin complexes on the EPR spectra were investigated. The ambiguity of the hyperfine structure (its presence or absence) corresponding to four nitrogen atoms in the spectra of oil vanadyl porphyrins correlates with the changes in the second coordination sphere of the nearest environment of the metal ion, namely, in methine bridges.

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Section: Introductionmentioning

confidence: 99%

EPR spectra of V(IV) complexes and the structure of oil porphyrins

Gilinskaya

2008

J Struct Chem

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“…Microstructural studies have indicated that most, if not all, pores have a partial lining of organic matter, which is preferentially oil-wet. It is well established that kerogen contains free radicals 7,8 , which act as paramagnetic centra. It is speculated that they are as effective in relaxing nuclear spins in oils.…”

Section: Oil-watermentioning

confidence: 99%

Unusual Logs in an Unusual Formation: NMR in Athel Silicilyte

Looyestijn¹,

Alixant²,

Hofman³

1998

Proceedings of SPE European Petroleum Conference

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TX 75083-3836, U.S.A., fax 01-972-952-9435. AbstractThe log evaluation of an expelling source rock is notoriously challenging because the kerogen and the generated oil coexist in the source rock. The Athel silicilyte is both an overpressured light-oil reservoir and a world-class source rock. In this unique geological setting found in the South Oman Salt Basin, reservoir characterisation is intimately associated with source rock evaluation. In the absence of any direct geological analogue, the initial petrophysical model was calibrated against extensive core analyses. Porosity interpretation was then based exclusively on wireline bulk density measurements. The limitations of this approach only became apparent as attempts to reconcile data from various sources failed. While efforts aimed at obtaining representative core material and establishing reliable core analysis procedures, in-situ calibration of the petrophysical model was also actively pursued. NMR logging was primarily introduced to reduce uncertainties affecting density-derived porosities in the presence of variable, unknown organic matter content. The first NMR log run in a silicilyte well could not be fully reconciled with density data. Laboratory NMR confirmed the log measurements, but more questions were raised when significant NMR signal was recorded on dry, cleaned samples at the time when new field data could not be explained. Athel silicilyte is unique, and with no reference to confirm or to invalidate new data and interpretation, consistency and integration are key to improving our understanding of the rock. A thorough review of NMR acquisition procedures and processing algorithms was undertaken with logging contractors; job planning was improved, new logging procedures were implemented, tool malfunctions were identified and remedied, processing methods were upgraded. Laboratory procedures were revisited, and NMR core measurements were complemented with additional, independent core analyses.Whereas the initial emphasis was on "effective" porosity determination, NMR logs and core measurements provided new insight into the Athel silicilyte rock. This includes: (i) strong indications that the rock may be mixed-wet; (ii) encouraging results in the area of permeability estimation; and (iii) indeed higher confidence in the assessment of effective porosity. A TOC (Total Organic Carbon) log can also be derived, which could find further application in source rock evaluation and the characterisation of organic-rich reservoirs. Integration of all available log data using a statistical approach now provides a consistent reservoir description, with limited core calibration requirements. Having successfully integrated NMR data to unravel the organic content of the rock, the improved petrophysical model provides the basis for sound reservoir characterisation, the foundation for better exploration, appraisal and development decisions.

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