Retraction notice to “Tight oil accumulation mechanisms of Triassic Yanchang Formation Chang 7 Member, Ordos Basin, China”

Abstract

Abstract The sedimentary environment, petrology, pore throat structure, migration and accumulation power, and accumulation process are analyzed to study the oil accumulation mechanism and distribution of Triassic Chang 7 Member tight oil in Ordos Basin. Chang 7 tight oil reservoirs are mainly semi-deep lake – deep lake sandy debris flow deposits and delta front underwater distributary channel deposits. The results of field emission scanning electron microscopy, CT scans and other high-resolution microscopy techniques show the physical properties of Chang 7 oil reservoirs are poor, micro- and nano-meter pore throats are developed, inter-granular pores and feldspar dissolved pores are the main pores, and tube- and strip-shaped pores are favorable reservoir space. The hydrocarbon generation and accumulation simulation of tight oil reservoirs shows that the hydrocarbon charging power of Chang 7 high-quality source rocks is strong. The oil saturation of the Chang 7 were more than 50% in the accumulation phase and even reached 70% or more with the continued power increase and oil enrichment. The source and reservoir rocks of Chang 7 tight oil coexist, so the hydrocarbons migrated under high pressure to migrate along relatively high permeable superimposed sands, reticular fractures and other pathways, and formed large-area continuous or quasi-continuous lithologic oil reservoirs.