Влияние траппового магматизма на нефтегазоносные горизонты (юг Сибирской платформы)

Abstract

The lack of determination of the hydrocarbon distribution regularities in the areas with widely developed basalt complexes significantly complicates the estimation of the prospects for the oil and gas potential of the ancient platforms. This is a challenge for the researchers of the Siberian Platform, which has recently become a new Russian oil and gas extraction base. For a long time, preceding the mass introduction of trap magma, the platform was subjected to intense deflection compensated by sedimentation with the formation of a large number of hydrocarbon deposits in the lower horizons of the sedimentary cover. The influence degree of widely manifested within the Siberian platform trap magmatism on the ontogenesis of oil and gas deposits has become the goal of the studies, which involve identification of the dependence between the thickness of the Osa production horizon and reservoir intrusions of dolerites, dependence of the phase state of deposits and the temperature gradient in individual fields in the south of the Siberian platform. The study uses the correlation methods for the lithologic and stratigraphic sections of the largest hydrocarbon deposits: Verkhnechonsky, Yaraktinsky, Kovykta, Srednebotuobinsky and others. The information is represented graphically in the diagrams. Having analyzed the data obtained according to the results of deep drilling in the known fields in the south of the Siberian platform, the authors have built linear graphs of the relationship between the thicknesses of the Osa productive horizon, salt-bearing fluid seal of Usolskaya suite and reservoir intrusions of Usolsky sill dolerites. Also the graphs of deposit phase state dependence on the temperature of fluid generation are constructed on the basis of the calculation of the possible formation depth of the field. There is a direct relationship between the thicknesses of fluid seal and reservoir intrusions of dolerites. It means that the horizon is preserved in the case when the fluid seal thickness increases as dolerite reservoir thickness increases. Gas condensate deposits are formed at higher temperatures.