Prospects of oil and gas potential of the Indigiro-Zyryansky trough based on direct geochemical data

Abstract

Within Eastern Yakutia, certain prospects for oil and gas potential are associated with a number of negative structural elements of the Mesocainozoic age. Given the presence of a powerful sedimentary cover and a relatively calm tectonic situation, the Indigiro-Zyryansky trough is considered the most promising territory for oil and gas. According to the results of deep drilling conducted in the late 1980s and early 1990s, the presence of sufficiently powerful Cenozoic age strata was established. After joint processing of the drilling data with the seismic survey materials, the thickness of Cenozoic sediments in the trough is estimated at 2 – 2.5 km. The expediency of rethinking the materials of geochemical testing together with the data obtained during deep drilling is noted. According to the peculiarities of the composition of gases obtained during deep drilling and testing of wells in the section of the Indigiro-Zyryansky deflection, there are two types of natural gas. The first type is associated with Paleogene deposits and, judging by its composition, has a microbial genesis (wells No. 272-01 and 272-02). The second type of gas obtained from Upper Jurassic deposits appears to be catagenetic and heavier in composition (well No. 272-05). An analytical review of the results of direct geochemical testing is made, which also confirms the presence of at least two different types of gases. At the same time, the gas characterized as deep has clear features similar to the gases of collapsing oil accumulations. It is assumed that near-surface gases enriched with nitrogen and carbon dioxide may be associated with carbonaceous deposits of the Upper Jurassic and Lower Cretaceous. It is recommended to conduct areal geochemical testing using artificial sorbents for aromatic hydrocarbons.