Hydrocarbon Charge History of Palaeogene Resivoir in Northern Dongpu Depression, Bohai Bay Basin

Aiming to determine the hydrocarbon charge history of the Palaeogene reservoir in the north of Dongpu Depression, a comprehensive analysis of 3D numerical simulation for the generation and expulsion history of the major hydrocarbon source rocks, asphalt fluorescence microscopic observation and fluid inclusion analysis were carried out in this study. There were two main stages of hydrocarbon generation and expulsion from the major hydrocarbon source rocks: the first stage was from the late Dongying depositional period of the Oligocene to the early uplift period of the late Paleogene; while the second was during the late Minghuazhen period of the Pliocene to the Quaternary accounting for 80% of the total generation. Based on the fluorescence microscopic features and the cause analysis, the asphalts discovered in the study area were divided into two types, carbonaceous bitumen, asphaltene bitumen and colloidal bitumen reflected an early hydrocarbon charge, whereas the oil bitumen reflected a second hydrocarbon charge. Hydrocarbon inclusions also indicate two distinct charges according to the diagenetic evolution sequence, inclusion petrography features combined with the homogenization temperature and reservoir burial history analysis.