松辽盆地北部西斜坡区萨尔图油层油气富集主控因素及成藏模式OA

Saertu reservoir in western slope area of northern Songliao Basin exhibits typical characteristics of exter-nal source accumulation,with complex patterns of hydrocarbon enrichment that constrain the progress of fine explo-ration.Based on geophysical,geochemical and exploration practical data,the basic geological conditions,main controlling factors of enrichment and accumulation patterns of hydrocarbon accumulation in this area are systemati-cally analyzed.The results indicate that the oil in Saertu reservoir of western slope area primarily originates from the mature source rocks of Qing-1 Member in Qijia-Gulong Sag,with hydrocarbon accumulation after long-distance lat-eral migration.A composite transport system composed of faults,unconformities and continuous sand bodies is the key to efficient long-distance migration of hydrocarbon across the slope zone.The regional monocline background,higher in the west and lower in the east,macroscopically controls the overall direction of westward hydrocarbon mi-gration,while the superimposed nose-like structural belts serve as favorable units for hydrocarbon enrichment.Based on trap genesis,3 types of accumulation patterns are summarized,including structural traps,lithological traps and composite traps.The research deepens the theoretical understanding of distal hydrocarbon accumulation in slope areas and provides important guidance for oil and gas exploration in western slope of Songliao Basin and similar areas.