Direct geochemical studies in the Vilyui syneclise

Abstract

The article provides an analytical review of the results of direct geochemical studies of the Vilyui syneclise, one of the promising areas for oil and gas in the east of the Siberian Platform. The work objective is to demonstrate the high efficiency of direct geochemical sampling for the search for oil and gas deposits in the conditions of a terrigenous section of the studied territory. It is shown that profile contrast anomalies were identified above productive structures. At the same time, a general increase of light hydrocarbon (LH) components from the flanks to its center and the confinedness of the most noticeable microconcentrations of heavy hydrocarbons (HH) to the periclinal sections of productive structures have been established. Также отмечается пятнистый характер профильных аномалий над продуктивными структурами. This phenomenon, apparently, indicates the predominant effect of filtration migration through various weakened zones from the source of hydrocarbons (deposits). The results of our own reconnaissance work carried out in 2016 on the southern pericline of the Middle-Vilyui gas condensate deposit are presented. The verification work was carried out to evaluate the effectiveness of the equipment and research methods. Relatively high values of benzene and toluene were recorded above the zones of occurrence of deposits T1-IIа and T1-III. It is assumed that the maximum values of B/T can be confined to the zones of oil accumulations. Based on the conducted geochemical samplings and historical experience, it is concluded that in combination with other geological and geophysical methods, direct geochemical studies will increase the reliability of forecasting the prospects of oil and gas potential of poorly studied territories. A recommendation has been made for the use of geochemical samplings in adjacent territories with a similar geological section.