Study On Distribution Characteristics Of Paleogene Source Rocks In Niger Delta Basin

The Niger Delta Basin is rich in oil and gas resources and is one of the most important oil and gas exploration basins in the world.Through the sequence stratigraphic division of the target horizon,the establishment of the sequence stratigraphic framework,and the seismic facies-sedimentary facies,the distribution characteristics of the source rocks are finally studied.Based on the comprehensive analysis of drilling,logging and seismic data in the study area,the Paleogene are divided into three secondary sequences: Paleocene,Eocene and Oligocene;Eight third-order sequences have been further determined: Danian-Thanetian,Ypresian,Lutetian,Bartonnian,Priabonian,Rupelian,Chattian,the Paleogene sequence stratigraphic framework of the study area is established.Sedimentary facies interpretation is carried out through single well facies,seismic facies analysis and cross-well profile.Different types of sedimentary facies and plane distribution characteristics of sedimentary facies in each sequence are studied.It is considered that source rocks of each sequence are developed in different sedimentary environments such as shore-shallow sea,Delta front,foredelta and underwater channel distributary bay.Based on the analysis of several representative well system tracts,the development model of dark mudstone is established.It is considered that dark mudstone mainly develops in transgressive system tract and high-level system tract,and the main sedimentary facies types are foredelta,underwater channel distributary Bay and shore-shallow sea.The comprehensive study shows that the source rocks in the study area are mainly of the Ipristine,Lutaite,Barton,Puliaben and Lupertian ranks,and the depositional thickness of the source rocks of the Barton and Lupertian ranks is the largest.