The mechanism of formation and prospects of non-structural traps in the South Caspian megadepression

Abstract

The article examines the geodynamic conditions for the formation and distribu- tion of non-structural traps in the oil and gas regions of Azerbaijan, such as the interfluves of the Kura and Gabirri, Yevlakh-Aghjabadi, Ganja, Lower Kura, the Baku archipelago, Shamakhi-Gobustan and Absheron. For this purpose, the surfaces of the Baikal basement, Mesozoic and Maikop deposits of the region were modeled and analyzed. The modeling revealed a submeridional uplift (positive tectonic element) that began to develop in the Maikop between the Kura and South Caspian basins. This has strongly influenced the folding and especially the formation of non-structural (tectonically sealed, lithologically limited, stratigraphic unconformity-associat- ed) traps in the region. As a result of the analyzes, we clarified the geotectonic characteristics of the formation of non-structural traps (tectonically sealed, lithologically limited, stratigraphic unconformity-associated) and compiled their distribution maps based on them. The analysis of these maps makes it possible to substantiate the features and reasons for the formation and distribution of non-struc- tural traps in the region. Thus, tectonically sealed traps were formed mainly in the oil and gas-bearing areas of the Kura and Gabirri interfluve, the Lower Kura, Shamakhy-Gobustan, Absheron and Baku archipelago, which are not only located in an active geotectonic zone, but likewise, the geological section of these oil and gas-bearing regions (OGBR) significantly differs from the Yevlakh-Aghjabadi and Ganja clay composition (clay rocks), and therefore, high parameters of the development of mud volcanism and clay diapirism are seen in the area. By contrast, in the Yevlakh-Aghjabadi and Ganja oil and gas regions, mainly effusive rocks have developed, which have incompetent properties and resist geotectonic – tangential-horizontal-compressive forces. Formed in this part of the region, thetraps associated with lithological wedging out have been mainly formed by covering the effusive or relief ledges. It should be noted that quantitatively, the traps with stratigraphic unconformity are developed relatively poorly and coincide with the distribution of lithologically wedge-out traps. The aim of the study was answ