鄂尔多斯盆地洪德地区中生界地层沉积构造演化及勘探前景OA

The Mesozoic strata in the Hongde Area on the western margin of the Ordos Basin have experienced multiple tectonic movements,resulting in complex and diverse structures.To clarify the hydrocarbon accumulation patterns of the Mesozoic strata in this area and to guide subsequent exploration,an integrated workflow combining well-seismic integration,seismic horizon flattening,and tectonic evolution analysis was applied to investigate the sedimentary-tectonic evolution charac-teristics.The results show that the Mesozoic strata in the Hongde Area have experienced four tectonic evolution stages:a tectonic uplift stage(end of the Triassic),a stable subsidence stage(Jurassic),a rapid subsidence stage(Early Cretaceous),and a tectonic inversion stage(Late Cretaceous).Two fault systems were mainly developed,namely the Indosinian and Himalayan fault systems.During the Indosinian stage,faults were dominated by north-east-trending and north-west-trending orientations,controlling the formation of fault-block traps.During the Himalayan stage,affected by compressional stress,the north-east-east-trending strike-slip faults developed and divided the study area into multiple north-east-trending rhombic fault blocks.The Early Cretaceous was the main hydrocarbon charging peri-od,with abundant hydrocarbon supply from high-quality source rocks of the Chang 7 in the central basin;large-scale accumulations formed on the western structur-al highs.Continuous subsidence of the Tianhuan Depression during the Early Cretaceous resulted in a structural configuration that is low in the west and high in the east,with early reservoirs damaged.Tectonic inversion occurred in the Late Cretaceous,and uplift of the western margin led to secondary adjustment of reservoirs,forming the present structural-lithologic reservoirs,which are characterized by low oil saturation,low oil-bearing amplitude,low-resistivity reservoirs,and complex oil-water relationships.Fault-block structural traps formed in the Indosinian stage are favorable zones for large-scale hydrocarbon accumulation,whereas low-am-plitude structural traps formed in the Late Cretaceous are key domains for refined exploration.The results provide guidance for subsequent exploration of the Mesozo-ic strata in the Hongde Area.