3D Structural Modeling and Analysis of the Devonian–Permian Succession in the Tasbulak Trough, Central Kazakhstan: Insights into Trap Formation and Preservation

The Devonian–Permian succession of the Tasbulak Trough in the Shu–Sarysu Basin contains confirmed gas shows (wells 462, 1-P Izykyr, 1-P Sokyr-Tobe, and 1-P Kamenistaya) and a sedimentary cover exceeding 5500 m but still lacks a unified 3D structural interpretation capable of explaining the distribution of gas-prone intervals. This study addresses this gap by digitizing and integrating legacy well and 2D seismic datasets to construct horizon-consistent three-dimensional structural surfaces for eight target horizons. The resulting model reveals a low-deformation structural framework dominated by a previously undocumented element—the Central Tasbulak Ridge—which exerts first-order control on fault segmentation, trap geometry, and gas preservation. Structural surfaces were synthesized with stratigraphic intervals to define reservoir–seal–trap relationships, highlighting the late Visean–early Serpukhovian carbonate subformation as the primary target interval. Building on these relationships, a prospect evaluation matrix was developed to classify structural, stratigraphic (including intraformational), and combination trap types together with their corresponding sealing units. The results demonstrate long-term tectonic stability, multi-level evaporitic seals, and inheritance-guided trap evolution, providing a reference framework for assessing gas prospectivity in data-limited intracratonic basins and advancing understanding of petroleum-system architecture in stable continental settings.