--> Abstract: Surface Geochemical Exploration in East Siberia: Methods and Case Histories, by Olga Shiganova, Peter Sobolev, and Svetlana Dykhan; #90078 (2008)

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Surface Geochemical Exploration in East Siberia: Methods and Case Histories

Olga Shiganova, Peter Sobolev, and Svetlana Dykhan
Geochemical Analytical Center, Siberian Research Institute of Geology, Geophysics and Mineral Resources, Novosibirsk, Russian Federation

For more than 15 years, our Institute has been conducting surface geochemical investigations to evaluate the oil and gas potential of exploration leads and prospects prior to drilling. Our geochemical exploration strategies and methods have been developed and refined by our extensive experience in different parts of East Siberia. Remote sensing and neotectonic investigations form the basis for designing our sampling network and geochemical analytical program. When possible, sampling of soil (summer) or snow (winter) is conducted along seismic profiles. Samples are extracted by thermal vacuum degassing and analyzed with gas chromatography. The resultant gas data are interpreted and integrated with all available geologic and geophysical information for the area.

The results of our surveys document very high correlation between the soil gas anomalies and structural contours of the hydrocarbon reservoir. For example, in the Omorinskoye gas condensate field there is an increase in sorbed soil gas ethane which coincides exactly with the gas-water contact in the reservoir. A similar ethane anomaly occurs along the oil-water contact in Yurubchenskoye field.

In other fields the microseepage pattern is more complex. Above the Kuyumbinskoye field, soil gas ethane anomalies are present but more discontinuous. Detailed studies of the underlying Riphean carbonate reservoir reveal a complex pattern of porosity, permeability, and oil saturation. It appears that maximum microseepage is associated with the more permeable zones in the Riphean carbonates, an observation that has since been confirmed by detailed seismic data and exploration drilling.

Surface geochemical surveys have proven to be highly cost-effective for evaluating and high-grading the petroleum potential of exploration prospects, even in geologically and logistically difficult area such as East Siberia.

 

AAPG Search and Discovery Article #90078©2008 AAPG Annual Convention, San Antonio, Texas