New Prospective Areas for Geological Exploration in Eastern Europe
NAMESTNIKOV, YURI G., Jebco Seismic, London, England
Eastern Europe is a highly complex geological region. The region comprises platforms of various ages, each exhibiting a variety of structural styles. The major tectonic elements often straddle more than one country, with each country usually interpreting the geological features differently. This complicates the study of both geology and petroleum occurrence.
The USSR Ministry of Geology (VNIIzarubezhgeologia) has been studying the Eastern European territory for the last 25 years. For 20 years the Institute has been carrying out joint scientific research with Eastern European countries. The research was aimed at studying the various problems of the petroleum geology of this territory as well as improving techniques of geological exploration. Our study of the geological structure and petroleum occurrence was done for the territory as a whole, notwithstanding national boundaries.
In order to consider the tectonic structure of Eastern Europe, various petroleum basins are outlined. They differ in structure, stratigraphic range, and lithology of sedimentary cover, stratigraphic range of petroleum occurrence and hydrocarbon phase.
Based on a series of structural-geological features, these basins are grouped into three categories: (1) platformal, (2) fold (in fold-nappe belts and intermontane depressions), and (3) combined (at the junctions of platformal and fold areas, i.e., foredeeps). The basins are divided into petroleum subbasins.
The petroleum basins have been intensively studied by both geological and geophysical techniques, especially the upper part of the sedimentary cover. In total, 880 oil and gas fields have been discovered. Of these, gas fields predominate (48%), with oil fields making up 27% and oil and gas fields 23%. There are some gas and condensate fields (2%). Almost all of the fields are at depths of 3-3.5 km or less. They usually occur in structural traps.
To scientifically estimate the petroleum prospectivity, VNIIzarubezhgeologia has recently analyzed the lithofacies characteristics of the sedimentary sequences occurring in Eastern Europe; the palaegeographical environments of sedimentation, organic matter and its maturity, and the distribution of reservoirs and seals.
The development of structural traps, the modeling of typical structures, and the prediction of such structures at greater depths have been studied in detail.
Particular attention has been paid to the prediction of stratigraphic trap zones and their classification, as well as to the delineation of areas with reduced concentrations on nonhydrocarbons (nitrogen, helium, CO2).
We have also studied the geodynamic evolution of the territory using palinspastic palaegeographic reconstructions.
As a result of these studies a series of lithofacies maps (18 maps at 1:1,000,000 scale), a tectonic map (1:1,000,000), a petroleum distribution map, a prospectivity map (1:2,500,000), and a series of geodynamic reconstructions have been produced.
As the result of this analysis, new petroleum exploration targets have been outlined. These new targets are in stratigraphic trap zones, in deep horizons (deeper than 3-3.5 km) and in areas defined as a result of geodynamic analysis.
AAPG Search and Discovery Article #91007© 1991 AAPG International Conference, London, England, September 29-October 2, 1991 (2009)