R.I. Timshanov, A.Yu. Belonosov, S.A. Sheshukov
 
Geochemical surveys in different exploration and prospecting stages
DOI: 10.31087/0016-7894-2018-3-103-109

Geochemical surveys are involved in the complex of exploration and prospecting activities mainly in the prospecting stage when petroleum potential of the vast areas is estimated. At the same time, with the increase of sampling density and rising a level of geochemical distributions detail, it becomes possible to use geochemical survey in solving tasks of field exploration and appraisal, and also searching for the overlooked reservoirs. Model of oil reservoir manifestation in geochemical fields was upgraded on the basis of the results of detailed geochemical studies completed in the fields of the Uvatsky region (prepared to exploratory drilling). A geochemical criterion is introduced — benzene to toluene ratio (B/T) in the near-surface deposits — that characterises conditions of hydrocarbon migration from reservoir to the ground surface. The criterion proposed uses the considerable difference in benzene and toluene content in oil reservoir (B<<T), as well as dissimilarity of these hydrocarbons in terms of biochemical stability, water solubility, and, in general, ability to migrate. B/T indicator allows estimating hydrocarbon migration conditions (impermeable beds efficiency and fault zones activity) and thus diagnose the nature of high concentrations of aromatic hydrocarbons occurrence. The model proposed is supported by subsequent exploratory and development drilling. Areas of high and increased HC content in near-surface deposits are consistent with the areas of oil and gas saturated reservoirs distribution. The direct correlation of well flowrates and presence of aromatic hydrocarbons in samples is observed (the samples were taken and studied 2–3 years before development drilling started). Thus, it can be argued that the results of geochemical surveys can complement seismic and well logging data, which are used in building a reservoir model and preparation of field development plan.

 

Key words: geochemical survey; prediction of oil and gas occurrence; exploration and prospecting; oil field; hydrocarbons migration.

For citation: Timshanov R.I., Belonosov A.Yu., Sheshukov S.A. Geochemical surveys in different exploration and prospecting stages. Geologiya nefti i gaza = Oil and gas geology. 2018;(3):103–109. DOI: 10.31087/0016-7894-2018-3-103-109.

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R.I. Timshanov

Trofimuk Institute of Petroleum Geology and Geophysics of Siberian Branch Russian Academy of Sciences; IPGG SB RAS, West-Siberian branch, Tumen, Russia;

timshanovri@ipgg.sbras.ru

A.Yu. Belonosov

Trofimuk Institute of Petroleum Geology and Geophysics of Siberian Branch Russian Academy of Sciences; IPGG SB RAS, West-Siberian branch, Tumen, Russia;

belonosovay@ipgg.sbras.ru

S.A. Sheshukov

Trofimuk Institute of Petroleum Geology and Geophysics of Siberian Branch Russian Academy of Sciences; IPGG SB RAS, West-Siberian branch, Tumen, Russia;

shershukovsa@ipgg.sbras.ru