Relationship Between Source Rocks And Sedimentary Facies Of Enping Formation In Huizhou Sag

The Pearl River Mouth Basin is an important petroleum-bearing basin in the northern part of the South China Sea.Its geographic location is the southern end of China's vast continent,the intersection of the Eurasian plate,the Indian Ocean plate and the Pacific plate.The Huizhou sag studied in this paper is located In the middle of the Zhuyi Depression in the Pearl River Mouth Basin,the Xijiang Sag is on the west,the Lufeng Sag is connected in the east,the northern uplift in the Pearl River Estuary in the north,and the Dongsha Uplift in the south.It is a proven hydrocarbon-rich depression.This article takes the Enping Formation in Huizhou Sag as the research object.Based on previous studies,under the guidance of petroleum geology,sequence stratigraphy,sedimentology,etc.,through comprehensive analysis of data such as drilling and logging,the The sedimentary study of the Enping Formation of Paleogene in Huizhou Sag and the comprehensive evaluation of source rocks explored the relationship between the two,and came to the following understanding:The lithology of the Enping Formation in Huizhou Sag is mainly gray sandstone and mudstone with coal lines,and they mostly appear in the form of interlayers.Among them,the source rock is mainly gray mudstone,accounting for up to 87%;Secondly,gray black,black and coal are few.The sediments of the Enping Formation in Huizhou Sag are mainly the shallow lake system and braided river delta system.The shallow lake system is widely developed in the middle of the basin,and the braided river delta sedimentary system is distributed around the depression.The kerogen types of the source rocks in the Enping Formation in Huizhou Sag are good,and they are mainly type II1 and II2.They are mainly medium-good source rocks,which are generally not very mature.The development and distribution of source rocks are affected by the sedimentary environment and are closely related to the sedimentary facies.The source rocks of Enping Formation in Huizhou Sag are mainly kerogen type II1 and II2,which corresponds to the "shallow lake-river" sedimentary system.The source rocks have high organic matter abundance,and light-coloredmudstones alternate with dark-colored mudstones and coal beds.It reflects that during the deposition process,it is relatively close to the source,there is temporary shallow water coverage,the source is sufficient and provides a periodic hypoxic-oxygen-deficient environment.Coal measure source rocks developed at a time when the deposition rate and settlement rate were relatively high and balanced.