Biomarker Characteristics Of The Xiamaling Formation In The Mesoproterozoic In Xiahuayuan Area Of Yanliao Rift

Many oil and gas reservoirs and high quality source rocks have been found in the strata,which indicates that the mesoproterozoic group has a certain oil and gas exploration potential.Sedimentary environment and source of parent material is the important influence factors of formation and evolution of the hydrocarbon source rocks.For clear the environment ande source types of hydrocarbon source rock in the ancient sedimentary,this paper takes Xiamaling Formation in north China as the research object,through the rock pyrolysis analysis,analysis of characteristics of biomarkers and various organic geochemical methods,discusses the hydrocarbon generation potential,sedimentary environment,organic matter and organic matter types of Xiamaling source rock,achieve the following:?1?The content of organic carbon of Xiamaling Formation is high,the fourth and third members are high-quality-good hydrocarbon source rocks,and the organic matters types are dominated by kerogen I and II₁.The second member is a medium hydrocarbon source rock,and the organic matters types are mainly II₁and II₂.The first member is differential source rock,dominated by kerogen II₂.Tmax is low,and relatively stable.The fourth and third members are low maturity stages,while the second and first members are maturity stages.?2?The carbon number of n-alkanes is distributed from n-C₁₃to n-C₃₂,which is dominated by low carbon number,without obvious odd-even advantage,indicating that the source type of organic matter is mainly low aquatic organisms?algae,bacteria,etc.?.The distribution of series of high-abundance tonified terpane,low ratio tricyclic terpane and C₂₄tetracyclic terpane also indicate that bacteria and other prokaryotes are important.?3?The ratios,Ts/?Ts+Tm?,C₂₉Ts/(C₂₉H+C₂₉Ts)and C₃₀*/C₃₀H were relatively low,indicating that the sedimentary environment of source rocks in the Xiamaling Formation was a weak reduction environment,and the maturity of source rocks was relatively low.Among aromatic compounds,according to the changes of MNR,MPDF,MPI and MDR,the overall maturity of the first to the fourth members was relatively low,and only the maturity values with different depths of the second and the first members were relatively high?4?The content of Pristine and Phytane in Xiamaling Formaion was relatively low,while the change of Pr/Ph was about 0.5-1.9.The relationship between SF/OF and Ph/Pr also shows that the sedimentary environment the source rocks of Xiamaling Formation is mainly a weak oxidation-reduction environment.Based on the above analysis,this paper considers that the sedimentary environment of organic matter in the source rocks of the Xiamaling Formation in the Mesoproterozoic era is a weak oxidation-reduction environment,and the materials of organic matter are mainly algae,bacteria and other low aquatic organisms.On the whole,maturity is low,and the hydrocarbon generation potential of the third and fourth members are the greatest.