Comparative analysis of sedimentation and oil and gas potential of the west-Siberian and the north sea sedimentary basins

Category Petroleum Geology
Group GSI.IR
Location International Geological Congress,oslo 2008
Author Myasnikova, Galina; Oksenoyd, Elena; Shpilman, Aleksandr
Holding Date 07 October 2008

Considered are two sedimentary basins which were formed on the young platforms with heterogeneous basement and the influence of the global planetary processes in different periods of time on their structure and oil- and gas-bearing potential of these basins. For the comparative analysis of the sedimentation dynamics a quantitative analysis of sedimentation velocities was carried out. To standardize actual velocities of sedimentation, calculated for the intervals of various duration, there were used procedures of "gliding window" and decomposition of sedimentation process to harmonic components-cosine curves, for each of which an equation was derived. A wave-like nature of the sedimentation process was established. A unified spectrum of harmonics was obtained. The harmonic with the time period T=540 million years depicts the most global history of the basin and at the same time it defines the basin’s energy resources. The harmonic with the time period T=200-220 million years reflects the role of galaxy cycles in sedimentation; the harmonic with the period of T=60-75 million years defines the periodicity of series accumulation, which are rich in organic matter or considerably differ in formation composition. Harmonics of T=27-35 million years and T=19-21 million years control sea transgressions and regressions, hiatuses and washouts in sedimentation, formation of caprocks and reservoirs.
Calculation of harmonics spectrum was carried out in both basins for the regions which are rich in oil and gas. It is shown that formation of the North Sea basin was influenced by intensive Hersynian orogenesis in Central Europe and Neogene movements in the Alps accompanied by sliding of glaciers from the Scandinavian shield into the basin; by movements in the Atlantic Ocean. For the West-Siberian basin it was established that development of Mesozoic-Cenozoic sedimentary cover was influenced by the planet splitting in Triassic time, accompanied by heavy volcanism, by shifting of the Earth magnetic field at the boundaries of Callovian and Bathonian, Hauterivian and Barremian ages; opening of deep depressions in the Arctic Ocean.
The evolution of the both basins reflects eustatic changes of the World Ocean level and the most recent tectonic movements. To study interrelation of the sedimentation dynamics and accumulation of energy resources, the interference of the two harmonics with periods of T=200-220 million years and T=60-75 million years was analyzed. It was found that the maxima on the velocity harmonics are unequivocally correlated with the growth of the total concentration of resources. The richest in oil and gas content are the sediments which were accumulated in the environment of sedimentation, when maxima on the both harmonics coincide; also, rich with oil and gas are the sediments, which formation was defined by one of the harmonics as a maximum, and according to the other it was related with intensive growth of velocities.