The Evaluation Of Meso-Neoproterozoic Source Rocks In The Northern Bohai Bay Basin

The Bohai Bay Basin is a large-scale basin rich in oil and gas resources in eastern China.The Changchengian System,the Jixianian System and Qingbaikouan System of the Meso-Neoproterozoic are extensively developed in the northern part of the Bohai Bay Basin.The stratigraphic thickness is large and the research potential is huge.The Meso-Neoproterozoic marine carbonate rocks in the northern part of the Bohai Bay Basin are widely distributed and the sedimentary rocks are thick and have great economic and social benefits for the study of carbonate rocks as source rocks.Due to the low degree of exploration in this area and the lack of downhole data,this paper aims to comprehensively evaluate the Meso-Neoproterozoic source rocks in the northern part of the Bohai Bay Basin,based on field outcrop data and predecessors research data.Which lays a foundation for studying the reservoir formation conditions and exploration potential of deep reservoirs in this area.A total of 75 samples source rocks were selected from the Meso-Neoproterozoic outcroping areas in the northern part of the Bohai Bay Basin.The total organic carbon,all-rock micro-component identification and petrophysical analysis were carried out.The qualitative and quantitative detection of chloroform extract and important biomarker of hydrocarbon source rock was carried out by gas chromatography-mass spectrometry.The Meso-Neoproterozoic strata in the northern part of the Bohai Bay Basin are mainly black,gray-black shale and marine carbonate.Based on the previous research results and the actual situation of the source rocks in this area,the lower limit of organic matter abundance of shale source rock in this area is set at 0.3% and the lower limit of carbonate rock source is 0.15%.Based on the comprehensive evaluation,the shale of the Meso-Neoproterozoic Xiamaling Formation,Tieling Formation and Hongshizhuang Formation in this area are good source rock,However,due to the thick layer of Wumishan Formation,still have a certain hydrocarbon potential.There are many kinds of biomarker compounds in this area.According to the results of the analysis of saturated hydrocarbon biomarker compounds,the organic matter of the source rocks of the Meso-Neoproterozoic are mainly derived from the lower organisms such as bacteria and algae,and the organic matter type is better.The prosperity of phytoplankton and the strong activity of bacteria in the middle and late Proterozoic algae are the important prerequisites and material basis of the organic matter in the Meso-Neoproterozoic hydrocarbon source rocks.The hydrocarbon generation in the Neoproterozoic region is much larger than that in the northern part of Hebei Province.