Genesis of pre-Jurassic oil deposits of Rogozhnikov group of fields by gravity exploration and geochemistry data (Tyumen region)

Abstract

Determination of "the major source" of hydrocarbons of pre-Jurassic oil-and-gas bearing complex defines the genesis of oil accumulations in pre-Jurassic base of Western Siberia and, consequently, the strategy and basis for prospecting technology. The main aim of the study is to inform specialists about author's results in application of gravity exploration and geochemical testing-within the Rogozhnikov license area (the Krasnoleninsk arch), which was recognized as "etalon" to study the problem of "the major source". The methods used in the study are complex interpretation of data of seismic survey, gravity exploration and drilling on the basis of geodensity modeling, petroleum-geological interpretation of "zones of deconsolidation", the layer-by-layer analysis of core of productive, above and under productive depositions on the content and molecular-mass distribution of oil hydrocarbons by the methods of organic geochemistry. As a result of studies on a traverse of the Rogozhnikov license area the authors have revealed the zone of deconsolidation of pre-Jurassic complex of formations, identified with the secondary reservoirs. The upright migration of oil hydrocarbons from Jurassic generation zones into pre-Jurassic deconsolidated formations was determined. The Jurassic concept of "the major source" is confirmed. The territories of focusing of already known reservoirs in ground floors of a sedimentary cover are determined as prior areas for prospecting. The geodensity modeling is recommended as a reliable and inexpensive method for detecting zones of deconsolidation in the foundation.

Keywords

• pre-Jurassic basis
• geodensity modeling
• secondary reservoirs
• geochemical researches of a core
• vertical migration
• oil genesis