Density model of the Kolomiya paleovalley along geotravers SG-I (67) Nadvirna – Otyniya – Ivano-Frankivsk

1
Ivano-Frankivsk National Technical University of Oil and Gas
2
Carpathian Branch of Subbotin Institute of Geophysics of NAS of Ukraine
3
Carpathian Branch of S. Subbotin Institute of Geophysics of the National Academy of Sciences of Ukraine

Purpose. The aim of this paper is to clarify the deep structure and prospects of the oil and gas potential in the Kolomiya paleo-valley along the seismo-geotravers SG-I (67), which run along the line Nadvirna-Kolomiya-Otyniya-Ivano-Frankivsk. Seismo-geotravers SG-I (67) and partially covers the Borislav-Pokutsky cover, crosses the Sambor and Bilche-Volitsa zones, and enters the Eastern European platform. Methodology. Geological-gravitational modeling of this geological section consists in a quantitative interpretation of the anomalous of Bouguer gravity, which is based on solving direct and inverse gravity problems for complex environments and is intended to be used for the construction of optimal geological density models of the geological section. The optimal geo-density model is a model that is consistent with the observed gravitational field, does not contradict the drilling and seismic data, and takes into account the interpreter's foresight (hypotheses). The prerequisite for the reliability of this technique is its geological subordination, the use of drilling data, seismic data, and geological-tectonic maps made according to the block structure of the basement and patterns of formation of the sedimentary complex and the zones of intersection of deep faults, which are the potential routes of fluid migration, and which create favorable conditions for the emergence of structural and lithologically or tectonically screened traps of hydrocarbons. In addition, geologic-gravity modeling is used to verify, refine, and specify the structurally dense constructions, which are performed in some other way. Results. The model of the seismo-geological section along the geotravers SG-I (67) was supplemented by the densities of the strata, which were determined from the drilling and modeling data, based on the interpretational profiles located side by side. The geometry of the structures and foundation blocks, based on the results of geological and gravity modeling, was refined. The distribution of the rock densities to a depth of 20 km was also detailed. As a result of the modeling there were revealed zones of compaction and decompaction within the stratigraphic complexes. The zones of decompaction within positive forms have been identified as promising for oil exploration. Originality. Structural and density features of the geological section along the SG-I (67) geotraverse have been clarified and detailed. This made it possible to obtain new data on the deep structure of the Kolomiya paleo-valley section and oil and gas prospects in its individual sections. It is established that the common features of the covers associated with deep-fault tectonics are displayed in the anomalous gravitational field, which indicates the reliability of the forecast of the elements of the deep tectonic and structural features of the region from the data of geological-gravity modeling. Practical significance. The obtained results testify to the high informativeness of geo-density modeling in the study of the deep structure of the Earth's crust in the complex seismic geological conditions of the Precarpathian trough. The revealed reduced density zones in the Paleozoic sediments of the Kolomiya paleo-valley are promising for setting up oil exploration works.

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