川中地区中新生代构造沉积演化及成藏OA

The Meso-Cenozoic of the Sichuan Basin is well-developed with tight sandstone gas reservoirs,which exhibit big potential for exploration and development.Taking the tight sandstone gas reservoirs of the Jurassic Shaximiao Formation in the Central Sichuan Area as a case study,this paper thermometry,paleopressure restoration,and reservoir diagenetic stage analysis,thereby clarifying the hydrocarbon accumulation history and its stages.Combined with the tectonic-sedimentary evolutionary history of the Sichuan Basin,the controlling effect of tectonic-sedimentary evolution on hydrocarbon accumulation in the Shaximiao Formation since the Meso-Cenozoic is revealed.The results indicate that during the Late Triassic,influenced by the Indosinian orogeny,continental coal-measure source rocks of the Xujiahe Formation were deposited,accompanied by the formation of compressive reverse faults.In the Early-Middle Jurassic,intense subsidence and sedimentary filling led to the development of lacustrine argillaceous source rocks in the Ziliujing Formation and thick mudstones intercalated with massive sandstones in the Shaximiao Formation.During the Cretaceous-Paleogene,the strata experienced continuous subsidence followed by uplift:in the Late Cretaceous,the source rocks entered the peak period of hydrocarbon generation and expulsion,while the reservoirs were compacted due to compaction and cementation,resulting in the formation of overpressured gas reservoirs.Since the Late Cretaceous,long-term uplift and denudation of the basin have caused a significant decline in formation pressure,triggering gas diffusion and adjustment,which led to the formation of low-pressure to normal-pressure gas reservoirs.