Inorganic Geochemistry of Oil: First Results of the Study Using the ICP-MS Method of the East-European and West-Siberian Oil Deposits

Kirill S. Ivanov¹, Yuriy N. Fyodorov², Yuriy L. Ronkin³, Yuriy V. Yerokhin³, Olga E. Pogromskaya³, and Irina N. Plotnikova^4
1Institute of Geology and Geochemistry of Russian Academy of Sciences, Ekaterinburg, Russia
²Tumen Department of KogalimNIPIneft, Russia
³RAS,
⁴Department of Geology of Tatarstan, Russia

New data have been obtained from 59 rare, rare-earth and other elements in crude oil from the West Siberian and the giant Romashkino deposit of the Tatarstan Republic. ICP-MS analyses made with high resolution mass-spectrometer ELEMENT 2. The principle geochemical anomalies in these samples include limitedly low content of most elements, except for the elements V, Ni, Cr, Ca, Sr, Na, Rb, Cs. For the West-Siberian oils marked a PGE (platinoid) presence in substantial quantities, especially of palladium. While normalizing on contents in primitive mantle [Taylor, McLennan, 1985] in oils are established positive anomalies on U, Sr, Ti, Y, Zr, and negative anomalies on Sm, Hf, Th, Nb, Nd. The rare-earth elements in the West Siberian oils demonstrate a particular type of trend characterized by enrichment of the light lanthanides (La/Yb=16-19) and a sharply positive Eu anomaly. The crude oil samples of the Romashkino deposit, when similarly normalized against the primitive mantle distribution in oil of rare and scattered elements, manifest positive anomalies of Sr, Rb, Cs, Hf, Zr, Eu, U and negative anomalies of Ti, Th. The content of PGE is about one order lower in the Romashkino crude oil than in the West-Siberian. Rare-earth elements in the Tatarian oil show approximately one type of trend with gradual enrichment of light lanthanoids with high La/Yb ratio up to 20 units and the presence of sharply positive Eu anomaly. Oils from the West Siberia and Tatarstan are of different geochemical types. The elemental distribution in the crude oil from all studied deposits does not match such of any known crustal rock. The experimental data presented should be taken into consideration during origin of oils is being discussed. The ICP-MS method begin a new stage in oil inorganic geochemistry study.

AAPG Search and Discovery Article #90072 © 2007 AAPG and AAPG European Region Conference, Athens, Greece