Key words: oil reservoir, oil-water contact, sandstones, bitumens, electron paramagnetic resonance.
Numerous manifestations of bituminous or so called “black sandstones” were identified in oil reservoirs of many oil fields of the Volga-Ural, Kaliningrad region and other areas, which are often associated with ancient oil-water contacts (OWC). Since the processes of natural transformation of oil in reservoirs can cover a significant volume of the deposits this makes it important for diagnostic of phenomena related to ancient OWC. The use of complex of instrumental techniques to study bituminous sandstones of the ancient OWC zones allowed us: a) to reveal transformation of minerals and inhomogeneity of hydrocarbons throughout the section of productive stratum of 15-18 meter in thick; b) to establish geological reasons and transformation mechanisms of conventional oils up to naphthides with anomalous properties; c) to demonstrate that the base of oil column serves as a collector for asphaltene precipitation from the primary heavy oil due to an influx of light crude oil in the multistage process of oil field formation; d) to estimate the time period when present-day reservoir has been filled by the light oil. The practical significance of the results obtained is discussed.
1. Mukhametshin R.Z., Role and importance of tar sands in producing formation (In Russ.), Collected papers “Prirodnye bitumy i tyazhelye nefti” (Natural bitumen and
heavy oil): edited by Belonin M.D., Proceedings of International Scientific and practical conference on the centenary of Prof. Uspensky V.A., St. Petersburg: Nedra Publ., 2006, pp. 231-245.
2. Mukhametshin R.Z., Geologicheskie osnovy effektivnogo osvoeniya i izvlecheniya trudnoizvlekaemykh zapasov nefti (Geological basis for efficient development and extraction of stranded oil): thesis of doctor of geological and mineralogical sciencesb Moscow, IGiRGI, 2006.
3. Sakhibgareev R.S., Vtorichnye izmeneniya kollektorov v protsesse formirovaniya i
razrusheniya neftyanykh zalezhey (Secondary changes of collectors in the formation
and destruction of oil deposits), Leningrad: Nedra Publ., 1989, 260 p.
4. Mukhametshin R.Z., Petrova L.M., Yusupova T.N., Nurgaliev D.K., Reconstruction of
the conditions the formation of the Devonian oil deposits of Bavlinskoye field and its importance (In Russ.), Collected papers “Opyt razvedki i razrabotki Romashkinskogo i
drugikh krupnykh neftyanykh mestorozhdeniy Volgo-Kamskogo regiona” (Experience in exploration and development of Romashkinskoye and other major oil fields of the
Volga-Kama region), Kazan': Novoe Znanie Publ., 1998, pp. 381-384.
5. Mukhametshin R.Z., Ivanov A.I., On Indication of the oil fields formation (In Russ.), Collected
papers “Novye idei v geologii i geokhimii nefti i gaza. Aktual'nye problemy geologii i geokhimii nefti i gaza” (New ideas in geology and geochemistry of oil and gas.
Actual Problems of geology and geochemistry of oil and gas), Proceedings of The 7th International Conference, Moscow: Geos Publ., 2004, pp. 354-357.
6. Berezin V.M., Gizatullina V.V., Yarygina V.O., Fixed oxidized oil in productive strata of
Bashkortostan fields (In Russ.), Proceedings of BashNIPIneft', 1983, V. 65, pp. 43-52.
7. Mukhametshin R.Z., Punanova S.A., Natural bitumen of Paleozoic deposits in Tatarstan: composition, properties, and the possibility of extracting (In Russ.), Collected papers “Vysokovyazkie nefti i prirodnye bitumy: problemy i povyshenie effektivnosti razvedki i razrabotki mestorozhdeniy” (High viscosity oil and natural bitumen: problems
and improving the efficiency of exploration and development), Proceedings of International Scientific and Practical Conference, Kazan': Fen Publ., 2012, pp. 95-99.
8. Petrova L.M., Yusupova T.N., Foss T.R. et al., Characterization of bitumens from the oilwater
contact zone of the Bavlinskoe oil field (In Russ.), Neftekhimiya – Petroleum
Chemistry, 2004, V. 44, no. 5, pp. 333-339.
9. Klubov B.A., Principal model of the formation of solid bitumen (In Russ.), Collected papers “Kondensirovannoe nekristallicheskoe sostoyanie veshchestva zemnoy kory”
(Non-crystalline condensed state of matter of the earth's crust), St. Petersburg: Nauka Publ., 1995, pp. 77-84.
10. Spravochnik po geokhimii nefti i gaza (Handbook of geochemistry of oil and gas): edited Neruchev S.G., St. Petersburg: Nedra Publ., 1998, 576 p.
11. Burov B.V., Nurgaliev D.K., Yasonov P.G., Paleomagnitnyy analiz (Paleomagnetic analysis), Kazan': Publ. of KSU, 1986, 168 p.
12. Hilton J., Greigite and the magnetic properties of sediments, Limnol. Oceanogr., 1990, V. 35, pp. 497-508.
13. Mukhametshin R.Z., Kayukova G.P., Geochemical aspects of the oil deposits formation of South-Tatar arch (In Russ.), Collected papers “Geokhimicheskoe modelirovanie i materinskie porody neftegazonosnykh basseynov Rossii i stran
SNG” (Geochemical modeling and source rock of oil and gas basins in Russia
and CIS), Proceedings of International Conference, St. Petersburg: Publ. of VNIGRI, 2000, pp. 119-127.
14. Andreeva L.N., Berezovskaya M.V., Tsyro L.V. et al., The use of instrumental methods for the characterization of the age and origin of oil (In Russ.), Proceedings of III International Conference on Petroleum Chemistry, Part 1, Tomsk: Publ. of RASKO, 1997, pp. 92-94.
15. Gilinskaya L.G., EPR spectra of V(IV) complexes and the structure of oil porphyrins (In Russ.), Zhurnal strukturnoy khimii – Journal of Structural Chemistry, 2008, V. 49, no. 2, pp. 259-268.