Research On Source Rock Geochemistry And Mechanism Of Abundance Of Organic Matter In Chagan Depression

This study, focusing on physical problems of Chagan depression, mainly deals withresearch on geochemical characteristics, hydrocarbon sources and mechanism of abundanceof organic matter. By means of techniques of GC, GC-MS, carbon isotopic analysis andbiomarkers identification, with application of new data, combined with geological research,and adoption of new methods, it statistically analyzed geochemical features of organic matter;Oil-oil correlation and oil-source correlation gave rise to identification of hydrocarbonsources; Sedimentology and geological technology recognized the most valuable formation oforganic carbon caused by sedimentation and analyzed mechanism of abundance of organicmatter in Chagan depression, and established lacustrine source rock model.Firstly, according to analysis of geochemical characteristics of organic matter withapplication of statistics and figures, a conclusion is made that primary source rock formationsare K1b2and K1s1,which indicates obvious variations on the aspects of thicknessdistribution, quality and types of organic matter among different formations in Chagandepression, reflecting vertical heterogeneities of source rock; With following procedure ofGC of saturated hydrocarbon, biomarkers and carbon isotopic analysis, oil-oil correlation andoil-source correlation are made. Petroleum of Chagan depression coming from source rock ofK1b2, explains heterogeneities of source rock result in that of hydrocarbon generarion fromsuits of source rock, namely, source rock with organic matter of high quality can be dedicatedto hydrocarbon accumulation, while those of poor quality may dedicate nothing tohydrocarbon generation; Through relative technical methods of sedimentology andgeochemistry, this study established sedimentation model for lacustrine source rock underdifferent tectonic settings and climate conditions, which reveals sedimentation anddistribution of source rock with different geochemical characteristics, finally leading to themechanism of abundance of organic matter: From the aspect of types of lake basin, it'sbalanced filling lake basin, and the influencing factor is primary production (i.e. nutrient).