Development Mechanism of Lacustrine High-quality Hydrocarbon Source Rocks of Nenjiang Formation in Northern of Songliao Basin

The first member of Nenjiang Formation in the northern Songliao Basin is a set of high-quality lacustrine Source rock, with an average TOC of 2.46% and an average hydrocarbon generation potential of 12.59 mg/g; The average asphalt “A” content reaches 0.2147%, and the organic parent material type is mainly composed of low-level aquatic algae. The first section of the Nenjiang Formation has entered a stage of thermal evolution with a large amount of oil generation. High quality Source rock is mainly developed in some areas of Gulong Sag and Sanzhao Sag. According to the characteristics of organic geochemical molecular biomarkers and element characteristics, this interval has high gammacerane, low Pr/Ph, and high-quality Source rock is formed in brackish water and partial reduction of deep and semi deep lake facies sedimentary environment. High productivity is the main controlling factor for the formation of this set of high-quality Source rock.