Geothermy and zoning of shale oil prospects of the Koltogor-Urengoy paleorift (southeastern part of West Siberia)

Abstract

Zoning of shale oil content at the southern segment of the Koltogor-Urengoy paleorift were done and it were correlated with geothermal field in the after Jurassic time. Territory of research is the north-western oil fields of the Tomsk region. The thermal history of the source rocks is criteria for predicting centers of oil generation and the formation of shale reservoir. It is cumulatively taking into account the temperatures of localized paleocenteres of oil generation. Researches are based on solving a direct problem of geothermy for a set of horizontal layers located in the lower half-space. Distribution of the oil generation density has been obtained and zones for searching for shale Bazhenov oil have been identified — it is the northwestern slope of the Northern-Parabel’ megamonocline; the northeastern slope of the Kaimysov arch; the Cheremshanskaya mesosaddle and the Traygorod mezoswell. The prediction is confirmed by direct signs of the oil content of the Bazhenov suite. Distribution of the oil generation density of the Bazhenov oil in different structural-tectonic conditions has shown that the intensity of hydrocarbons generation on positive structures is similar to the generation density in depression. “Traces” of anomalous heat flow are not in the rift zone there during the Cenozoic period. Zone does not correlate with the paleotemperatures distribution in the after Jurassic time. There is the reflection of the paleorift; as an object with anomalous structural characteristic; in the distribution of generation density at the Upper Jurassic shale oil. The energy relationship of the paleorift with the distribution of heat flow density and paleotemperatures of the source rocks has not been identified. Zoning of the shale oil determined promising territories for setting up geological survey. The results are worth of attention in the context of the theoretical foundations of oil and gas geology of Western Siberia; the theory of rift systems and the oil and gas potential of the West Siberian plate.