Origin, migration, and characterization of petroleum in the Perdido Fold Belt, Gulf of Mexico basin

Abstract

Herein, the characteristics and origin of petroleum in the Perdido Fold Belt (PFB) were studied and the petroleum migration processes and system elements are discussed. The molecular compositions and stable carbon isotopes indicate that natural gases in the PFB are mainly organic and have similar origins. Further, they are mainly sapropel type gases and originated from kerogen cracking. The oil in this region has a high API gravity and contains a relatively high sulfur content. The light hydrocarbon values indicate that most of the oil samples are sapropel type oil. Based on the geochemical characteristics of petroleum, Tithonian is considered to be the dominant source rock in the PFB. Various parameters regarding petroleum maturity suggest that the natural gases and oil are mature. The calculated temperature and vitrinite reflectance of the oil samples indicate that petroleum charging occurred from the Middle to Late Eocene. API gravity and sulfur content are related to maturity and herein, indicate that the Tithonian source rocks are mainly type II-S kerogen and the associated high API gravity of petroleum can be primarily attributed to this kerogen. Petroleum migration in the PFB was jointly controlled by salt activity and petroleum generation, wherein. The active faults and the Wilcox sandstones acted as petroleum migration pathways, allowing large petroleum reservoirs to form from the Middle to Late Eocene.