Geotectonic features of structure and petroleum potential of Northern Ustyurt

The authors discuss geological and geophysical, and structural and tectonic features of Northern Ustyurt architecture, which is situated in the west of the Turansky plate. They present the analysis data and results of previous studies, main stages of investigations and new data obtained in recent years. The purpose of this work was to update geotectonic features of internal structure of the region in the context of reflectors, tectono-stratigraphic units, as well as to substantiate of petroleum potential. Accumulated data and geological and geophysical materials, as well as the results of Integrated Studies of Sedimentary Basins in the Republic of Kazakhstan regional project (2009-2013) made a basis for the studies. Taking into account the results obtained during the course of previous studies, the authors give an integrated estimate of prospecting practices and methodological approaches. The concept of tectonic framework of the region was accounted for; and the analysis performed demonstrated that the concept was not perfect because of geographical zoning principle applied in the eastern part of the Northern Ustyurt. The major uncertainties in assessment of structure and potential of tectono-stratigraphic levels within the pre-Jurassic and Jurassic-Cenozoic sedimentary sequences are considered. The key features of structural geometry of the Basement Top and pre-Jurassic sequence are revealed; position and features of Palaeozoic sequence in the section are updated. The authors appraise structure and position on the II-nd order structures and individual blocks, and update their relationships in the context of main reflectors. Trends of fault tectonics elements and local structures are updated using integration of exploratory drilling, seismic and anomalous potential field data; at the same time, occurrence of hydrocarbon accumulations with certain phase content was estimated. As a result, zoning of the territory according to prospectivity level is performed, which was based on areal patterns of large troughs and highs structure, distribution of local objects of different types, morphology, and genesis. The authors substantiate high prospectivity of different-order swell-like rises and structural complications on the shoulders of Shalkarsky, Koltyk-Kulazhatsky, South Bozashinsky, Samsky, Barsakelmessky, and Sudochy troughs, and monoclines of Mansualmassky and Arystanovsky flats. They appraised highly the potential of Palaeozoic series, where large highs of massive syn-depositional type are considered to be the priority local objects. With an eye on further studies, zoning of the territory with identification of highly promising and promising zones is substantiated together with zones having uncertain potential; in accordance with this, focus areas for further prospecting were specified