| Microbial transformation is an important link in converting biological organic matter into geological organic matter, makes its long preserved in the strata, namely microbial formation plays an important role in the process of hydrocarbon source rocks. Effect of micro-organism on organic matter is throughout the whole process of hydrocarbon source rocks formed. The early diagenetic process is an important part of the action of microorganisms, which mainly includes aerobic and anaerobic process. But, it is difficult to obtain a complete sample of microbial transformation in the early diagenetic process as the sampling technique and sedimentary environmental constraints in the natural environment. On the other hand, the existing study on the characteristics of hydrocarbon source rocks by studying on the process of thermal simulation of algae without considering the role of microorganisms.In view of the above problems, this study obtained samples by artificially adding microorganism and controlling the oxygen environment simulation to early diagenetic processes, weighted microorganisms, and eliminated sampling technology and sedimentary environment. Studied on morphological, biochemical composition (biochemical composition--polysaccharide, protein, lipid) and element change(C, H, N and trace heavy metal elements) to understand the early diagenesis, hydrocarbon source rock forming process by modern comparative examples.The main conclusions are as follows:(1) Determine the time of experimental stageHydrolysis stage was7days. Ammonification stage was12days, nitrification stage was15days, and sulfur oxidation stage was18days. Then the total of aerobic reaction was45days. Denitrification stage was43days. Sulfate reducing phase was27days. Then the total of facultative anaerobic reaction was70days.(2) Morphological observationThe material form had been unable to distinguish in the anaerobic30days, were amorphous body shape. Cell morphology of cyanobacteria disappeared on the ninety-fifth days, and cyanobacteria produce fluorescent substance was degraded on the fifty-third day.(3) Biochemical compositionKelp:The content of polysaccharide raised in the aerobic stage and in the anaerobic stage on day30th to60th. It descended in the other stage. The content of protein had been rising. The content of lipid raised from facultative anaerobic stage. Comparison with various data of the control group and the experimental group showed the rate of change of biochemical components increased with microbial activity, microorganisms played a positive role in the early diagenesis process.Microcystis aeruginosa:The content of polysaccharide raised in the sulfur oxide stage and descended in the other stage. The content of protein raised in the ammoniation stage and descended in the other stage. The content of crude fat descended from the nitrification stage to the denitrification stage, and raised in the other stage.(4) C, H, N elementsKelp:The relative percentage content of C, H element was reduced in the conversion process. The content of N element was increased in the aerobic stage, declined in the other stage. Microbial action made the control group C/N, C/H ratio were higher than the experimental group.Microcystis aeruginosa:The relative percentage content of C, H, N element, C/H ratio and C/N ratio increased after hydrolysis. C, N decreased as microbial growth and metabolism to consume carbon and nitrogen sources after adding microbial. The relative content of H element remained unchanged. The C/H ratio decreased, and the C/N ratio remained unchanged.(5) Trace heavy metal elementsThe chang of Fe, Mn, Zn, Pb, Cr, Cd, and Cu element was irregular in the microbial transformation experiment of kelp. It cannot be used as an index of oil and source rock correlation. |
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