Abstract
The North Ustyurt Oil and Gas Region (OGR) in terms of territory is located within the borders of two countries. The majority of it is situated within the territory of Western Kazakhstan, while a smaller part (to the east) is in Western Uzbekistan. Geographically, the North Ustyurt OGR is bounded to the north by the Caspian Lowland, to the east by the Aral Sea, and to the west by the North-Buzashin Oil and Gas Zone. From a tectonic perspective, its northern-northwestern boundary is marked by the North Ustyurt fault system, separating the North Ustyurt from the Caspian Depression with Upper Paleozoic complexes. The southern-southwestern boundary is formed by the Central Ustyurt dislocations and the Tokubay-Tuakyr thrust-and-fold system, while the eastern boundary is defined by the Aral-Kyzylkum uplift zone. In comparison to neighboring oil and gas regions, the hydrocarbon potential of the North Ustyurt Oil and Gas Region (OGR) is indeed less pronounced, but recent discoveries in the Tepke area suggest that it is not fully explored. In the Kazakhstani part of the region, approximately 10 fields have been found in the Jurassic, Cretaceous, and Paleogene fields, while in the Karakalpakstan part of Uzbekistan, there are 17 fields in Mesozoic and Paleozoic deposits. For this region, structural and tectonic control over hydrocarbon presence is evident. All identified fields are associated with steps, uplift zones, and monoclines located on the periphery of major flexure systems. Additionally, there are broad patterns in the distribution of fields based on the phase state of hydrocarbons, albeit at a relatively coarse scale: western areas are characterized by oil, north-eastern areas contain dry methane gas, and eastern-southeastern areas, bordering Uzbekistan, have gas condensate fields. The volumetric distribution of oil and gas fields clearly corresponds to three hypsometrically uplifted segments of flexures: the Arystanov Step, Akkulka Fold, and Shagyrly-Shomyshtinsky Prominence (Figure 1). It is important to note that all of these segments are bounded by significant faults, which does not exclude the possibility of hydrocarbon recharge from deep hydrocarbon generation centers [1].