Abstract: The Shunbei Area of the Tarim Basin is abundant in ultra-deep hydrocarbon resources,however,the spatiotemporal correlation of the geological conditions for hydrocarbon accumulation is complex and not well understood.Therefore,by analyzing testing data and using basin modeling techniques,the processes of hydrocarbon generation,migration and accumulation in the Shunbei Area were reproduced;the causes for variability in hydrocarbon property were investigated;the mechanisms of ultra-deep hydrocarbon migration-accumulation and the reservoir-formation models were revealed.The results indicated that the Middle-Late Caledonian and Late Hercynian were the critical periods for hydrocarbon migration and accumulation,whereas during the Himalayan period,hydrocarbon reservoirs were reworked and redistributed.Three hydrocarbon-generation patterns developed in the source rocks of the Shunbei Area,namely,an oil-rich/gas-poor double-peaked pattern,a balanced oil-gas double-peaked pattern,and a gas-rich/oil-poor double-peaked pattern.Strike-slip faults served as the primary migration pathways.The hydrocarbon volumes in sub-salt,inter-salt,and supra-salt layers exhibited theinversely-proportioned relationship of"one wanes,the other waxes":the Xiaoerbulake Formation and Sayarik Formation,being closer to source rocks,preferentially experienced migration and accumulation,while low-upwelling zones acted as transfer stations for hydrocarbon re-migration.Laterally,the oil and gas fields in the Shunbei Area were controlled by the main fault belts and exhibited a belt-like distribution.Vertically,the main fault zones connected to source rocks and branched upward;the greater the fault activity was, the more developed was the fracture-vuggy system.Within the same fault zone,multi-stage mixed hydrocarbon charging was the dominant factor causing variations in hydrocarbon properties at different locations.Overall, the reservoirs in the Shunbei Area were characterized by "multi-source relay hydrocarbon supply,dominant fault-controlled migration and multi-phase mixed charging accumulation".This study provides a methodological reference for future hydrocarbon exploration in the Shunbei Area.

Key words: hydrocarbon accumulation process, dynamic simulation, carbonate reservoir, ultra-deep, the Shunbei Area, the Tarim Basin