Consolidated crust layering of astrarhan arch

About the author:

Victor V. Pykhalov, Cand. Sci. (Techn.), Associate Professor, Geology of Oil and Gas Department, Astrakhan State Technical University (Astrachan)

Abstract:

According to the seismic data, energetically expressed reflectors with different gradients of unclear nature are found out in the consolidated crust formation of Astrakhan Arch. Morphological layering of consolidated crust is manifested in the form of deep intracrustal troughs and «diapirs». Intracrustal ‘diapers’ are characterized by positive anomalies of the gravity in the gravity field. The constructed model of consolidated crust layering of Astrakhan Arch shows that its formation is due to the influence of intense compressive stresses and the subsequent intrusion of the lower crust to the top due to creep deformation. The study of the Paleozoic sedimentary cover morphology, lithofacies analysis,and paleoreconstruction indicate that the formation of the consolidated crust layering refers to the Early Permian. Consequently, the formation of intracrustal layering had a significant impact on the secondary conversion of pore space rocks and fractured reservoirs composing before Permian Astrakhan carbonate array. Drilling data, including studies of core material on vitrinite indicate the link between the morphology of the lower crust and the distribution of reservoir beds in D evonian-Carboniferous section of Astrakhan Arch. This link is manifested in sharp decrease of collectors in Bashkir section and their increase in the underlying sediments spread over the arches of intracrustal «diapirs». The identified pattern can be used while planning oil and gas exploration.

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