Evaluation of the Late Cretaceous-Cenozoic Uplift and Petroleum System Modeling of the Russian Barents Sea Basin

Peter Sobolev¹, Bernhard Cramer², Nikolay Sobolev¹, Viktor Vasiliev¹, and Evgeniy Petrov^1
1VSEGEI, St.-Petersburg, Russia.
²BGR, Hannover, Germany.

The Late Cretaceous-Cenozoic exhumation of the northeastern European margin is an important event crucially impacting on the timing of petroleum generation and entrapment. For the western Barents Sea the scale of the uplift and its effect on the petroleum systems was investigated with several methods and the results are published in many articles. For the Russian Barents Sea the uplift was not considered in detail so far. Geophysical logging data from the Russian Barens Sea (more than fifteen wells) were compiled and processed. The joint interpretation of sonic, gamma-ray, resistivity logs were used to calculate porosity and shale fraction in siliciclaric rocks. Comparison of the porosity-depth lines from different wells reveals the rate of compaction for the different kinds of sediments and different level of erosion. On the other hand, we used vitrinite reflectance data for the independent evaluation of the uplift and for most of wells it is about of 500 m.

Petroleum system modeling in a 1D mode was started on the example of several wells with different tectonic environments and various kinds of petroleum systems. They include large oil and gas fields such as “Shtokmanovskoe” (gas condensate deposits in Jurassic sandstones at the deeply buried rift structure, the South-Barents basin), “Severo-Kildinskoe” (central Barents Sea, gas pool in Triassic sandstones) and “Prirazlomnoe” (oil pools in P-D reservoirs, the Pechora Sea).

Three source rocks are considered as mainly contributing to the petroleum inventory of the basins. These are Devonian carbonates, as well as sapropelic shales of Lower Triassic and Upper Jurassic ages. For the three well locations the degree and dynamics of MZ subsidence are supposed to be crucial parameters for the source rocks to be matured sufficiently for oil and gas generation. At the Shtokmanovskoe and Severo-Kildinskoe fields Upper Jurassic shales are thermally immature. The conditions in the Severo-Kildinskoe field were favorable for the gas generation during MZ. Gas condensate trapped in Jurassic reservoirs at the Shtokmanovskoe field probably migrated from the deeper Triassic source rocks. The Jurassic shales may reach the necessary thermal maturity only in the most deeply buried parts of the basin. In the Pechora Sea (the Prirazlomanoe field) favorable conditions for petroleum generation during MZ times were realized in PZ oil-prone source rocks.

AAPG Search and Discover Article #90096©2009 AAPG 3-P Arctic Conference and Exhibition, Moscow, Russia