Abstract: To determine the controlling factors of oil enrichment in the Upper Wilcox Formation of Perdido Belt, the commercial and non-commercial fields of the Upper Wilcox are taken as the research objects. This study integrates the analysis of effective hydrocarbon supply range, oil and gas transmission mode, matching relationship between trap formation and hydrocarbon generation and expulsion period and preservation conditions. The study discusses the controlling factors of oil and gas enrichment in Wilcox Formation and petroleum accumulation model. The study shows that the scale of hydrocarbon supply area has obvious control effect on field scale; there are three vertical migration modes in the Upper Wilcox Formation, i.e. along-source, toward-source and back-source. Among them, along-source and toward-source migration modes are advantageous. Trap formation and hydrocarbon generation-expulsion period match well, hydrocarbon supply is sufficient and reservoir scale is large; It is a necessary condition for oil enrichment and a small scale of seriously damaged reservoirs. Three accumulation models of Upper Wilcox Formation in Perdido Belt are established, among which“ double supply along-source” and“ single supply toward-source” are favorable for oil enrichment and are favorable models for searching large size fields in Perdido Belt.

Key words: Mexico, Perdido Belt, Upper Wilcox Formation, oil enrichment factors, accumulation model