断裂主控区小尺度碳酸盐岩缝洞储集体发育特征与分布模式

he Ordovician carbonate reservoirs in the Tahe Oilfield are characterized by deep burial depth, strong heterogeneity, and diverse reservoir types, among which small-scale fracture-cavity reservoirs (millimeter to tens of centimeters) in fault-dominated zones represent a significant new frontier for oil and gas exploration and development. Based on integrated analysis of core, logging, and seismic data, this study systematically investigates the geological characteristics and controlling factors of these reservoirs, establishing a developmental model that reveals small fractures are predominantly vertical and high-angle (75.7%), while cavities are mainly calcite-filled (chemically filled types dominate), with localized effective storage space preserved. Seismically manifested as "chaotic weak reflections" or "small weak bead-like" features, these reservoirs show enhanced development within 400 m of NE-trending faults and their intersections, with distribution jointly controlled by Caledonian karstification (reflected by Upper Ordovician residual thickness) and fault-fold deformation (characterized by principal curvature), where dissolution intensifies in high-strain zones and further expands in areas where coherence attributes reveal superposition of overlying drainage systems and faults. The reservoirs develop through a ternary "fault-fold-paleokarst" coupling model, exhibiting deep vertical extension (400 m below T74 interface) that distinguishes them from epigene karst-dominated reservoirs in weathering crust areas, providing both a theoretical basis for predicting concealed small fracture-cavity reservoirs in Tahe and guidance for exploring analogous complex carbonate reservoirs.